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Dorsiflexion Capacity Affects Achilles Tendon Loading during Drop Landings
Abstract
Evidence suggests a link between decreased dorsiflexion range of motion (DROM) and injury risk during landings. The purpose of this study was to determine the effect of weight-bearing DROM on ankle mechanics during drop landings.
Forty-eight men (mean ± SD = 22.5 ± 4.7 yr) were measured for DROM. Participants performed drop landings onto a force platform at two vertical descent velocities (2.25 ± 0.15 and 3.21 ± 0.17 m·s(-1)), while EMG activity of four shank muscles and three-dimensional ankle joint kinematics were recorded. Participants were classified into low (37.7° ± 2.5°) and high (48.4° ± 2.5°) DROM groups.
Ground reaction force, EMG, dorsiflexion angle, plantarflexion moment, and Achilles tendon force outcome variables were all equivalent for the two DROM groups during each landing condition. However, the low DROM group performed each landing condition at a significantly greater percentage of their DROM and displayed significantly more ankle eversion throughout most of the movement. The low and high DROM groups displayed DROM percentages of 27 ± 11 and 10 ± 11 (P = 0.013), 32 ± 9 and 23 ± 9 (P = 0.056), 60 ± 13 and 46 ± 13 (P = 0.004), and 66 ± 16 and 54 ± 9 (P = 0.003) when they encountered the peak plantarflexion moments, Achilles tendon force, eversion angles, and dorsiflexion angles, respectively.
Participants with a low DROM absorbed the landing impact forces with their plantarflexor muscle-tendon units in a more lengthened and everted position. Athletes with a low DROM may be more likely to regularly overload their plantarflexor muscle-tendon units, thereby potentially exposing themselves to a higher likelihood of incurring injuries such as Achilles tendinopathy.
... This flexion of joints cushions the impact forces experienced through the hip, knee, and ankle joints, reducing the body's downward momentum, leading to reduced forces absorbed over a longer period of time (Bressel & Cronin, 2005;Chockley, 2008). Due to these mechanisms of energy dissipation, it has been suggested that increased ankle dorsiflexion capacity is associated with lower peak Achilles tendon force (Whitting et al., 2011). Inadequate force absorption and dissipation is suggested to contribute to lower limb injuries through greater force experienced at the hip, knee, and ankle joints (Devita & Skelly, 1992). ...
... Dorsiflexion ROM of the right ankle joint was measured to the nearest centimetre using a validated Knee to Wall test (Bennell et al., 1998) (Figure 1(a)). Ankle dorsiflexion ROM was included as limited ROM is a risk factor for Achilles tendinopathy and has been suggested to affect the Achilles tendon force during landings (Whitting et al., 2011). (Bennell et al., 1998) that was used to assess ankle dorsiflexion ROM. ...
... The peak Achilles tendon force estimated during the three Irish dancing landing tasks assessed in the current study ranged from 3.05 to 5.26 times BW, occurring at initial foot contact. To provide context, the peak Achilles tendon forces estimated in the current study are similar to the peak Achilles tendon forces, of 5.7 times BW, reported from a sample of physically active men during single-leg drop landings (n = 48, mean age: 22.5 years) (Whitting et al., 2011). Plyometric training has been suggested to lead to adaptations in the structure and dissipative properties of the Achilles tendon, leading to the tendon's ability to withstand greater forces (Fouré et al., 2010). ...
Achilles tendinopathy is prevalent among Irish dancers, believed to be due to aesthetic technical requirements and high-impact landing tasks. However, the peak Achilles tendon force during Irish dancing-specific landing tasks has not been quantified. Furthermore, the influence of fatigue is unclear. This study aimed to quantify the peak Achilles tendon force during three common Irish dancing landing tasks and investigate the effects of fatigue on this force. Twelve nationally competitive Irish dancers completed the landing tasks prior to and following a fatigue protocol. A Vicon motion analysis system and AMTI force plates were used to calculate sagittal plane ankle joint kinematics during landing to estimate peak Achilles tendon force. Three independent measures (Rating-of-Fatigue scale, Flight time: Contraction during a counter movement jump and jump height during the landing trials) were used to evaluate participant fatigue between conditions. Results revealed a significant difference in peak Achilles tendon force between the three landing tasks, however, no significant difference was observed between pre- and post-fatigue. Further research is required to investigate the effects of the landing technique used in Irish Dancing on peak Achilles tendon force with the aim to reduce peak Achilles tendon force and the risk of developing Achilles tendinopathy.
... Several lower limb injuries, such as ankle injuries (Youdas, McLean, Krause, & Hollman, 2009), ACL ruptures (Wahlstedt & Rasmussen-Barr, 2015), Achilles (Whitting, Steele, McGhee, & Munro, 2011) and patellar tendon injuries (Bisseling, Hof, Bredeweg, Zwerver, & Mulder, 2008;Malliaras, Cook, & Kent, 2006;Whitting et al., 2011), and hamstring strain injuries (Gabbe, Bennell, Finch, Wajswelner, & Orchard, 2006;Gabbe, Finch, Bennell, & Wajswelner, 2005;van Dyk, Farooq, Bahr, & Witvrouw, 2018) have been associated with restricted ankle dorsiflexion range of motion (ROM). In particular, the cut off score of >2 cm has been previously suggested as the smallest worthwhile change to identify impairments in ankle dorsiflexion ROM (Charlton et al., 2018). ...
... Several lower limb injuries, such as ankle injuries (Youdas, McLean, Krause, & Hollman, 2009), ACL ruptures (Wahlstedt & Rasmussen-Barr, 2015), Achilles (Whitting, Steele, McGhee, & Munro, 2011) and patellar tendon injuries (Bisseling, Hof, Bredeweg, Zwerver, & Mulder, 2008;Malliaras, Cook, & Kent, 2006;Whitting et al., 2011), and hamstring strain injuries (Gabbe, Bennell, Finch, Wajswelner, & Orchard, 2006;Gabbe, Finch, Bennell, & Wajswelner, 2005;van Dyk, Farooq, Bahr, & Witvrouw, 2018) have been associated with restricted ankle dorsiflexion range of motion (ROM). In particular, the cut off score of >2 cm has been previously suggested as the smallest worthwhile change to identify impairments in ankle dorsiflexion ROM (Charlton et al., 2018). ...
... Such findings could have important implications for the decrease in ankle dorsiflexion ROM, which has been posited as a predisposing factor for increasing the risk of hamstring strain injuries (Gabbe et al., 2005;Gabbe et al., 2006;van Dyk et al., 2018) in football, and Acute and chronic effects of competition on ankle dorsiflexion ROM 7 of several of the most prevalent injuries in other sports (e.g. basketball, volleyball) such as, ankle injuries (Youdas et al., 2009), ACL ruptures (Wahlstedt & Rasmussen-Barr, 2015), Achilles (Whitting et al., 2011) and patellar tendinopathies (Backman & Danielson, 2011;Bisseling et al., 2008;Malliaras et al., 2006). ...
The aim of this study was to investigate the acute (a football match) and chronic (a whole season) effects of competition on ankle dorsiflexion ROM in professional football players. Forty football players participated in this study. Ankle dorsiflexion ROM was recorded to examine acute (pre-match, immediately post-match and 48 h post-match) and chronic (pre-season, mid-season and post-season) effects of competitive football. In addition, it was found that players had restricted mobility measures on ankle dorsiflexion as >2 cm change between baseline measures (pre-match and pre-season). The training load of all played matches was estimated using a global positioning system (GPS) and RPE. Pre-season ankle dorsiflexion ROM was greater compared to mid-season (8.1% in the dominant, and 9.6% in the non-dominant leg) and post-season (13.8% in the dominant, and 12.5% in the non-dominant leg). In addition, around 30% of all players showed restricted ankle dorsiflexion ROM values in post-season compared with pre-season. Related to acute effects, ankle dorsiflexion ROM increased after a match (5.8%) in the dominant ankle, and this value decreased (2.65%) 48 h post-match when post-match measurements in both dominant and non-dominant ankles were compared. The progressive decrease in ankle dorsiflexion ROM throughout a season can be an indicator of increased risk of injury and may be reinforce the need of prevention actions such as stretching exercises and eccentric strength training in professional football players. In addition, these findings suggest to implement specific recovery strategies aiming at minimizing alteration in ankle dorsiflexion ROM 48 h post-match.
... Its range of motion is usually assessed by measurements that rely on the relative positions of the foot and lower leg (shank). 1,22 The ankle is often considered to be a basic hinge joint with its primary movement occurring in the sagittal plane as dorsiflexion and plantar flexion. 16 With this plane providing the largest range of movement, it is essential for function in both highly dynamic movements, but also in activities of daily living. ...
... 16 With this plane providing the largest range of movement, it is essential for function in both highly dynamic movements, but also in activities of daily living. 13,21,22 However, it must be noted that ankle rotations are triplanar, across multiple joints and include movements such as inversion and adduction (supination) and eversion and abduction (pronation). Therefore, sagittal dorsiflexion range of motion for the foot relative to the shank, actually includes a complex multijoint combination of rotations. ...
... 11,17 Therefore, having adequate ankle mobility is considered important for functional movements such as squatting, 15 balance tasks and movements of daily living, 12 as well as for dynamic sporting movements such as high velocity landings. 2,22 Being able to assess functional weight-bearing ankle DROM does not require lengthy clinical training. While a standard extendable joint goniometer is typically used to assess the DROM in the ankle, other methods (eg, digital inclinometer, knee-to-wall load oRIGINaL RESEaRCH Foot to shank ratio: Does it influence ankle dorsiflexion range of motion in the knee-towall assessment technique? ...
Aim: To establish the correlation between scores of ankle dorsiflexion range of motion (DROM) when assessed using a knee-to-wall assessment score and standard extendable joint goniometer.
Study design: Foot to shank ratio influence was assessed on two separate occasions by the same rater using two measures of ankle DROM i.e.: i) the knee-to-wall assessment linear score, and ii) the joint angle recorded with a standard extendable joint goniometer.
Participants: Nine females and six males (combined mean age = 26.5 ± 6.2 yr; range = 19-37 years, height = 1.73 ± 0.85 m, mass = 76.5 ± 18.6 kg) volunteered to participate in this study.
Methods: Foot and shank length was determined prior to assessment of ankle DROM. Following a standardised warm-up, ankle DROM was assessed using two methods: i) knee-to-wall method; ii) and standard extendable joint goniometer. Measures were taken twice with each technique and on two separate occasions. Measurement of ankle DROM alternated between each ankle (i.e. one measurement taken on the right ankle followed by one measurement on the left ankle and then repeated), with the first measure on both test occasions being the knee-to-wall assessment.
Results: A significant positive correlation was found between foot length and shank length for both right (p < 0.001, r = .877) and left (p < 0.001, r = .880) side. No other significant correlations were found between all other variables (p > 0.05).
Conclusion: Findings indicate that neither the length of the foot nor the length of the shank influences ankle joint mobility. Further, their relative lengths, as determined by a foot-to-shank length ratio, had no impact on ankle DROM when measured using the knee-to-wall assessment method. As a result, either assessment method can be used with confidence by clinicians and sports trainers to determine ankle DROM.
... The AT forces estimated for both the recreational and elite players in the present study is similar to those estimated in healthy male subjects during single-leg jump landing tasks over a barrier (AT forces between 4633 and 6286 N) and in barefoot drop landing (between 3565 and 3713N) (Whitting et al., 2011;Gheidi et al., 2018;Gheidi and Kernozek, 2019). The peak AT forces found in the present study and in the aforementioned studies are generally higher than the peak AT forces found from invivo measurements in hopping (3500-4000N) (Fukashiro et al., 1995;Lichtwark and Wilson, 2005). ...
... To understand the potential consequences of the AT forces estimated in the present study it could be noted that AT failure ranges between 4635-5579 N was previously reported in cadaveric studies (Wren et al., 2001;Rees et al., 2008) and the highest measured AT force in our study was 8632 N. Although cadaveric studies may underestimate the failure limit in healthy tissue, these values still indicate that the eccentric landing characteristics observed in badminton during the initial contact phase directly followed by a concentric phase may impose greater loading of the AT, making it a potential high-risk AT injury movement in badminton (Fukashiro et al., 1995;Whitting et al., 2011;Gheidi and Kernozek, 2019). ...
Achilles tendon (AT) rupture is common among recreational male badminton players. We hypothesize that a landing technique following forehand jump strokes with the landing foot in a neutral position often performed by recreational players and occasionally by elite players may expose the AT to higher loads than a scissor kick jump (SKJ) technique with the leg/foot externally rotated. The study aimed to investigate if recreational players could reduce the load in the AT when adopting the SKJ technique compared to their habitual landing technique with the foot in a neutral position and secondarily to compare the AT force between recreational players and elite players. Ten recreational male players performed simulated jump strokes in a biomechanical laboratory using both their original technique and the SKJ technique traditionally used by elite players. For comparison reasons ten elite players performed SKJs. Landing kinematics and AT forces were captured and calculated using 3D movement analysis. The landing leg was more externally rotated in the recreational players' adjusted technique (78 ± 10 degrees, p < 0.001) compared to 22 ± 21 degrees in recreational players' original technique. The peak AT force of the recreational players was significantly higher for the original technique compared to the adjusted technique (68 ± 19 N/kg vs. 50 ± 14 N/kg, p = 0.005). Additionally, the peak AT forces observed during the recreational players’ original technique was higher, though not significantly, than those observed for elite players (55 ± 11 N/kg, p = 0.017). / = 0.016 due to a Bonferroni correction. These findings indicate that recreational badminton players that normally land with the foot in a neutral position, may reduce their AT load by 25% when adopting the SKJ technique of elite players and land with the leg/foot in an externally rotated position.
... With increase in football participation in Nigeria, an upsurge in the incidence of injuries has been reported with an overall injury incidence of 113.4 and time-loss incidence of 15.6 injuries/1000 match-hours. Several lower limb injuries such as ankle injuries, anterior cruciate ligament (ACL) ruptures and Achilles tendon injuries have been associated with restricted ankle dorsiflexion range of motion (ROM) (10). A few studies have analyzed whether football-specific adaptations would occur in the ankle and hip rotation ROMs despite the fact that restricted scores have been considered as primary risk factors for some of the most common injuries in football, such as ankle sprains and knee osteoarthritis respectively (11). ...
... It has also been associated with functional limitations generally and ankle dorsiflexion has been reportedly reduced as well (12,15). The quest to identify injury risk factors in sports has been ongoing in the world of sports medicine (10). Currently, there are no documented epidemiological data on Achilles tendinopathy and its associated risk factors among footballers in Nigeria hence he need for this study. ...
Background. Achilles tendinopathy (AT) is a major foot and ankle overuse injury which has been reported to be prevalent in running and jumping sporting activities, especially football which has witnessed increased participation in recent times. However, there are no epidemiological data on tendinopathy in footballers in Nigeria. The aim of this study was to determine the prevalence of Achilles tendinopathy and associated intrinsic risk factors among Nigerian footballers. Methods. Participants were 151 registered football players recruited from various football clubs in Lagos State, Nigeria. Selected intrinsic factors of age, gender, body mass index (BMI), random blood glucose and bilateral ankle dorsiflexion and plantarflexion were evaluated. AT was determined with the Royal London Hospital Test and ultraso-nography. Principal Component Analysis (PCA) was used to determine the association between AT and selected intrinsic risk factors and significance set at p < 0.05. Results. The prevalence of AT was 15.9%. There were significant associations between elevated BMI (p = 0.027), left ankle dorsiflexion (p = 0.035) and right ankle plantar-flexion (p = 0.008) with Achilles tendinopathy. No significant association (p > 0.05) was found between Achilles tendinopathy and blood glucose level. Conclusions. Elevated body mass index, reduced ankle dorsiflexion and plantarflexion are risk factors for Achilles tendinopathy.
... and 3664.03n by Whitting et al.2011and 2012, respectively; during barefoot a drop landing where the aT forces were based on inverse dynamics which utilize the net ankle moment and aT moment arm to determine aT force. 16,17 our data showed a higher aT force in landing by 9-10% using inverse dynamics then static optimization within a musculoskeletal model. These slightly higher results may be explained by ML direction (P=0.024) while the interaction effects (P=0.028) ...
... participants in Whitting et al.2011 and 2012 performed a drop land from a height of 32 and 72cm onto one leg. 16,17 This again shows that jump height may have the greatest influence on aT loading variables. The present study showed higher aT loading during jump. ...
Background:
Athletes in jumping and running sports have a high incidence of Achilles tendon (AT) injuries. We compared AT loading during jumping and landing phases in anteroposterior (AP) and mediolateral (ML) directions.
Methods:
Sixteen males (age: 21.6±1.8 years, height: 178.4±6.4 cm, weight: 76.4±11.2 kg) performed single leg AP and ML jump-landings during both propulsive (jump) and braking (land) phases. Inverse dynamics and static optimization were used to determine muscle forces. AT cross sectional area was measured with ultrasound. AT force was divided by cross sectional area to determine stress while strain was determined from previous data. Two-way repeated measures analysis of variance (α=0.05) compared several variables (vertical ground reaction force (VGRF), ankle and knee angle, ankle joint muscle moment arm, external ankle moment arm, AT tendon force, stress, and strain) between movements (jump-landings) and directions (AP/ML).
Results:
AT loading was higher during jump than land in the ML compared to AP direction. VGRF was higher during land versus jump with no direction effect (AP/ML). An interaction showed a higher VGRF during the AP land and ML jump. The ankle joint moment arm was lower in jump and AP direction at peak tendon stress. External ankle moment arm at peak tendon stress was higher in jump and ML direction with an interaction. A larger external ankle moment arm occurred in ML but the change was less in the jump.
Conclusions:
Higher tendon loading occurred during the jump and ML direction. This may provide insight into both injuries and rehabilitation efforts.
... 27,28,38 Despite substantial changes to their musculoskeletal structure and function throughout the 12 months of their growth spurt, 38 girls in the present study displayed no significant changes in their 3D ankle motion or joint loading during landing throughout this time. This finding is consistent with the results of Whitting et al, 36 who concluded that ankle motion during landing is dictated by the task itself 11 reported an increase in peak ankle dorsiflexion moments and ankle stiffness in girls throughout their growth spurt, with no change in the peak dorsiflexion angle. However, it is important to note that participants in this previous study performed a vertical drop landing, 11 which is a task vastly different from the horizontal landing performed in the present study. ...
... However, it is important to note that participants in this previous study performed a vertical drop landing, 11 which is a task vastly different from the horizontal landing performed in the present study. This would suggest that no matter how vast or rapid the musculoskeletal changes experienced by girls during the adolescent growth spurt, they are unlikely to alter ankle motion when performing a dynamic horizontal landing task, 36 although ankle biomechanics are affected during a vertical landing maneuver. 11 During the transition from the earlier stages (test 1) to the later stages of puberty (test 4), girls in the present study displayed a reduction (approximately 6°) in knee flexion, which was accompanied by an increase in hip flexion (approximately 6°), when performing the horizontal landing task. ...
Background:
Despite the rapid musculoskeletal changes experienced by girls throughout the adolescent growth spurt, little is known about how their lower limb landing technique changes during this time.
Purpose:
To investigate the longitudinal changes in the 3-dimensional lower limb kinematics, joint moments, and muscle activation patterns displayed by girls when performing a horizontal landing task throughout their adolescent growth spurt.
Study design:
Descriptive laboratory study.
Methods:
A total of 33 healthy 10- to 13-year-old girls, in Tanner stage II, with a maturity offset of -6 to -4 months (time from peak height velocity) were recruited. According to her maturity offset, each participant was tested up to 4 times during the 12 months of her growth spurt (maturity offset: test 1 = -6 to -4 months; test 2 = 0 months; test 3 = 4 months; test 4 = 8 months). During each test session, participants performed a horizontal leap movement, during which ground-reaction forces (1000 Hz), lower limb muscle activity (1000 Hz), and kinematic data (100 Hz) were collected.
Results:
Throughout the growth spurt, girls displayed a decrease in knee flexion (P = .028), increase in hip flexion (P = .047), increase in external knee abduction moments (P = .008), and decrease in external hip adduction moments (P = .003) during the landing movement.
Conclusion:
During their adolescent growth spurt, pubescent girls displayed a change in the strategy with which they controlled their lower limb to land after performing a horizontal leap movement. This change in the landing strategy has the potential to increase the risk of anterior cruciate ligament injuries toward the latter stages of the adolescent growth spurt.
Clinical relevance:
The outcomes of this research provide a greater understanding of the changes in the landing strategy used by pubescent girls throughout the adolescent growth spurt. This can assist in the development of screening tools designed to determine "at-risk" landing biomechanics during puberty.
... de flexión dorsal del tobillo se compensa mediante la alteración de la marcha (Gatt & Chockalingam, 2011), por ello, en el momento de la exploración, es necesario tener en cuenta posibles mecanismos de compensación, los cuales deben ser controlados para garantizar un análisis puro de la FDT y para un correcto diagnóstico (Whitting et al., 2011). ...
... FDT (Backman & Danielson, 2011; C.-M. Fong, Blackburn, Norcross, McGrath, & Padua, 2011; D. T.-P. Fong, Hong, Chan, Yung, & Chan, 2007; Whitting et al., 2011 ...
... These movement patterns have been associated with increased risk of Achilles tendon injury (Wyndow, Cowan, Wrigley, & Crossley, 2010), and knee ligament injury (Hewett et al., 2005), both of which are common netball injuries. Although there is limited evidence for compensatory pronation in association with reduced ankle sagittal excursion (Whitting, Steele, McGhee, & Munro, 2011) a previous study investigating laceup braces during a sports-specific netball jump suggested the brace may reduce frontal plane motion and prevent this compensation strategy from being utilised (Vanwanseele et al., 2013). The theory of knee valgus compensation is supported by studies showing greater frontal plane knee motion or peak knee valgus during landing in association with low dorsiflexion (DF) ROM (Malloy, Morgan, Meinerz, Geiser, & Kipp, 2014;Sigward, Ota, & Powers, 2008). ...
... The theory of knee valgus compensation is supported by studies showing greater frontal plane knee motion or peak knee valgus during landing in association with low dorsiflexion (DF) ROM (Malloy, Morgan, Meinerz, Geiser, & Kipp, 2014;Sigward, Ota, & Powers, 2008). However, these studies investigated goniometric DF ROM rather than excursion during landing and a number of studies have shown that low goniometric DF ROM does not necessarily result in reduced peak DF angle on landing (Fong et al., 2011;Malloy et al., 2014;Whitting et al., 2011). Furthermore, the only previous study investigating frontal plane knee motion with lace-up braces found no change in frontal plane knee motion during a drop land despite a reduction in knee and ankle sagittal excursion (Simpson et al., 2013). ...
Objectives:
Investigate the impact of lace-up ankle braces on landing biomechanics.
Design:
Within-subject repeated measures. Participants completed a drop jump, drop land, and netball-specific task in braced and unbraced conditions.
Setting:
Biomechanical research laboratory.
Participants:
Twenty female high school netballers.
Main outcome measures:
Leg, knee, and ankle stiffness, knee/ankle stiffness ratio, knee and ankle sagittal excursion, peak vertical ground reaction force, time-to-peak vertical ground reaction force, and loading rate.
Results:
In the brace condition leg stiffness increased bilaterally during the drop land (ES = 0.21, 0.22), ankle stiffness increased bilaterally during the drop jump (ES = 0.37, 0.29) and drop land (ES = 0.40, 0.60), and knee/ankle stiffness ratio decreased in all three tasks (ES = -0.22 to -0.45). Ankle sagittal excursion decreased bilaterally during the drop jump (ES = -0.35, -0.53) and drop land (ES = -0.23, -0.46), and decreased in the lead limb during the netball jump (ES = -0.36). Knee excursion decreased bilaterally during the drop jump (ES = -0.36, -0.40) and in the lead limb during netball task (ES = -0.59). Lead limb TTP was greater during the netball jump (ES = 0.41).
Conclusions:
Lace-up ankle braces may increase leg and joint stiffness and reduce joint excursion during landing but do not appear to affect landing forces. The observed effect on landing biomechanics may predispose young netballers to injury.
... Mixed findings have been reported in studies in which ankle dorsiflexion has been investigated. Some authors have shown associations between dorsiflexion ROM and landing kinetics 94 or kinematics, 94,95 whereas others have not.95,357,358 Further, some authors have demonstrated joint-level associations (e.g., ankle or knee moments) but not system-level associations (e.g., vGRF) 129 with ankle dorsiflexion ROM. ...
Jumping and landing activities are the most common mechanism of injury in professional ballet dancers. There is limited evidence, however, that has elucidated the moderators of load experienced when jumping and landing in ballet. This thesis aimed to describe injury epidemiology, establish reliable methods of assessing strength and jumping, and explore the factors that may influence lower extremity load during jump landings in professional ballet dancers.
A five-year injury epidemiology study revealed an incidence of medical attention and time-loss injuries of ~3–4 and ~1 per 1000 h of exposure, respectively. The mechanism of injury was jumping and landing activities in ~30–40% of time loss injuries. A systematic review found limited evidence that ballet dancers demonstrate externally rotated lower extremities, extended lower extremities prior to landing, and ankle-dominant jumping strategies.
Two methodological studies established the within- and between-session reliability of vertical ground reaction force (vGRF) across several maximal isometric force tests and three-dimensional ankle mechanics during landing in turnout and parallel foot positions. The reliability of vGRF during maximal isometric force tests across the squat, standing plantarflexion, and seated plantarflexion positions demonstrated excellent reliability (intraclass correlation coefficients (ICC): 0.92–1.00) and low variability (coefficient of variation (CV): 2.0–6.5%). Three-dimensional ankle mechanics demonstrated within- (ICC: 0.17–0.96; CV: 1.4¬–82.3%) and between-session (ICC: 0.02–0.98; CV:1.3–57.1%) reliability ranging from poor to excellent, with, ankle excursion, peak ankle angle, and jump height demonstrating the greatest ICC values (ICC: 0.65–0.96; CV: 1.4–57%).
The final two studies investigated jump landings in professional ballet dancers. A linear discriminate analysis revealed that three-dimensional ankle mechanics could discriminate different ballet foot positions, such that jump landings in fourth and fifth positions required a greater range of motion and ankle joint power when compared to other foot positions. Lastly, two linear mixed-effects models indicated that peak ankle joint moments and vGRFs have poor associations with strength, ankle dorsiflexion range of motion, and three-dimensional ankle excursions (R2: 0.01–0.02). Sex, foot position, and individual variation are more appropriate factors to consider when assessing the load experienced at a joint or system level.
This thesis provides a thorough insight into injury, strength, and jumping in professional ballet dancers. To that end, this thesis has identified burdensome injuries and their mechanisms in professional ballet dancers alongside practical and reliable strategies to measure the physical attributes that may moderate the load experienced by a dancer upon landing.
... The DLT test is more specific for articular restrictions in ankle joint, indirectly affecting other structures. Ankle dorsiflexion asymmetry was previously associated with acute traumatic injuries for hamstring (Van Dyk et al., 2018), and ACL injuries (Amraee et al., 2017), chronic overuse injuries in ankle instability , along with patellar and Achilles tendinopathy (Malliaras et al., 2006;Whitting et al., 2011). Ankle, ACL, and tendon injuries had a lower prevalence in this population, contributing to these findings. ...
Purpose: (A) To characterize the epidemiology of injury at an elite youth football academy. (B) To investigate the differences between injured and non-injured elite youth footballers in musculoskeletal screening and workload variables, for lower extremity non-contact soft tissue injuries; and for groin located and muscular type injuries. Methods: (A) Prospective analysis of time-loss injuries from one hundred eighty-four elite youth male football players (age: 16.2±2.2 yrs) in a Portuguese academy (U14-U23) during the 2019-2020 season. Injury frequency, burden, incidence, and patterns were calculated. (B) A match-paired case approach was used to investigate differences between injured (n= 56) and non-injured (n= 56) groups for preseason musculoskeletal screening variables (passive knee fall out (PKFO), adductor squeeze (ASQZ), adductor squeeze bodyweight ratio (ASQZ/BWratio), dorsiflexion lunge test (DLT); single-leg countermovement jump (SL-CMJ)) and workload variables before injury (Cumulative sum; monotony; strain; acute: chronic workload ratio (ACWR); week to week change) using internal load (sRPE). Groin located injuries (n=14 vs n=14) and muscular injuries (n= 27 vs n=27) were also investigated. Results: (A) A total of 129 time-loss injuries were observed. Injuries were more frequent in training but had a higher incidence and burden rate in match context. Overall incidence was 2.7 per 1000 hours, and burden rate 59.3 days lost per 1000 hours. The thigh was the most frequent location. Quadriceps was the most injured muscle group, mainly by sprinting and shooting mechanisms. Moderate injuries were more frequent, with a mean of 21.9±28 days lost to injury. Under 17 was the most affected team, with the highest-burden cross-product. (B) ASQZ/BWratio was higher in non-injured players compared with injured players for lower body non-contact (0.64±0.11 vs 0.59±0.11; p=0.025) and groin injuries (0.64±0.08 vs 0.54±0.11; p=0.007). No other workload and musculoskeletal variable had significant differences between groups. Conclusions: Characteristics of injury incidence, burden, and patterns differ among squads in elite youth football. Non-contact injuries in pre-adolescent players remain frequent, representing a threat to the young football player's safe development. ASQZ/BWratio could be used to identify risk of injury for lower body non-contact and groin injuries. More data is necessary to clarify which musculoskeletal and workload factors are relevant to youth football injury occurrence.
... 15,17,19 Over the past 35 years, many studies have attempted to quantify the load borne by the Achilles tendon during various activities, such as cycling, 20,21 walking, 15,[22][23][24][25][26][27] running, 15,22,24,25,[27][28][29][30][31][32][33][34][35][36][37] and strengthening exercises performed with or without additional load. 15,22,25,[38][39][40][41][42][43] To date, no clear progression including all categories of exercises involving the Achilles tendon has been established. Such a synthesis requires a comparison of the data obtained in the different studies. ...
Background:
The Achilles tendon (AT) can be exposed to considerable stress during athletic activities and is often subject to pathologies such as tendinopathies. When designing a prevention or rehabilitation protocol, mechanical loading is a key factor to consider. This implies being able to accurately determine the load applied to the AT when performing exercises that stress this tendon.
Materials and methods:
A systematic review was performed to synthesize the load borne by the AT during exercises/activities. Three databases (Pubmed, Embase and Cochrane) were searched for articles up to May 2021, and only the studies assessing the AT load in newtons relative to body-weight (BW) on humans during activities or exercises were included.
Results:
Most of the 11 included studies assessed AT load when running or walking (N=10), and only 3 tested exercises usually performed during rehabilitation. The load on the tendon ranged from 2.7 to 3.95 BW when walking, from 4.15 to 7.71 BW when running, and from 0.41 to 7.3 BW according to the strengthening exercise performed.
Conclusion:
From the collected data, a progression of exercises progressively loading the Achilles tendon, as well as the possible connections with walking and running activities, could be defined. However, the trends highlighted in the relationship between the tendon loading and walking or running speeds present some inconsistencies. Further research is still needed to clarify them, but also to complete the data set in healthy and injured people.
... There was a significant difference in the motion of the KFP between these two tasks, suggesting that its motion was related to the force transmitted through the Achilles tendon (Ghazzawi et al. 2009). Differences in ankle and knee range of motion between tasks, which affect the force transmitted along the Achilles tendon (Wakahara et al. 2009;Whitting et al. 2011), may influence the motion of the KFP. These differences between tasks support the need to describe the motion of the KFP while walking. ...
The distal calcaneal wedge of the Kager's fat pad (KFP) has the mechanical role of lubricating the region between the Achilles tendon and calcaneus during ankle movements. The purpose of this study was to determine the reliability of real-time ultrasound (RTUS) in visualizing the motion of the KFP during walking in adults. Recordings obtained using RTUS (13-MHz linear array transducer, IOE 323, MyLab 70, Esoate, Genoa, Italy) of the Achilles enthesis region (N = 52) of 47 participants (ranging from 21–79 years in age) while walking on a motorised treadmill at their preferred speed were analysed by three blinded assessors. Motion of the KFP was rated on a 4-point Likert scale (normal to absent). There was good agreement (κ [95% confidence interval] = 0.646 [0.643–0.649]) among the three examiners, with very good agreement (0.823 [0.818–0.828]) when classifying the motion as normal. There was a poor correlation between the motion of the calcaneal wedge and participants’ age (0.23–0.32). RTUS provides an adjunct to routine clinical examination to determine if there is normal motion of the calcaneal wedge during walking. This may be of benefit in patients with posterior heel pain for whom abnormal KFP motion is implicated.
... A previous study showed that a soft-landing strategy could lead to higher knee flexion, reducing landing impact force [46]. Additionally, actively changing the stiffness of the ankle is equivalent to increasing the range of motion [47]. However, this approach can alter the dynamics and the kinematics of the lower limbs, thus providing further evidence for our approach. ...
The stop-jumping task is one of the most important technical actions in basketball. A previous study showed 70% probability of non-contact ACL injuries during stop-jumping tasks. Therefore, the present study aimed to investigate the differences in lower extremity biomechanical changes between the rear foot as the initial contact area to terminate the jump (SJR) and the fore foot as the initial contact area to also terminate the jump (SJF) during the horizontal landing during a stop-jumping phase. In total, 25 male amateur Ningbo University basketball athletes from China were recruited for this study. The participants were asked to jump vertically by using two different stop-jumping strategies. Kinematic and kinetics data were amassed during a stop-jumping task. Statistical parametric mapping (SPM) analysis was used to find the differences between SJR and SJF. Our results indicated that the change of different ankle range of motion caused significantly different values for knee angle (p < 0.001), velocity (p = 0.003) (p = 0.023) (p < 0.001), moment (p = 0.04) (p < 0.001), (p = 0.036) and power (p = 0.015) (p < 0.001) during the stop-jumping phase and the horizontal landing phase. The same biomechanical parameters of the hip joint were also significantly different for hip angle (p < 0.001), moment (p = 0.012) (p < 0.001) (p < 0.001), and power (p = 0.01) (p < 0.001) (p < 0.001). These findings indicate that altering the primary contact at the ankle angle might effectively reduce the risk of a knee injury.
... For example, compared to drop landings, when landing simulated, dry-land aerial surfers displayed significantly greater peak tibial accelerations (pooled mean ± standard deviation: aerial landing 15.7 ± 2.6 g vs drop landing 9.2 ± 2.4 g) and moved through significantly less percentage of their static ankle range of motion in their lead (front) limb (aerial landing 66.3% vs drop landing 81.3%) (LE Lundgren et al., 2016). Landing with the lead ankle in dorsiflexion at initial board-wave contact, rather than the plantar flexed alignment typically displayed during drop landings (Niu et al., 2011;Whitting et al., 2007Whitting et al., , 2011, has also been associated with successfully performing the Frontside Air and Frontside Air Reverse in the ocean during surfing competitions (Forsyth et al., 2018). Using a restricted range of ankle motion and a dorsiflexed alignment when landing aerials is likely due to a surfer's need to maintain contact with the deck of their surfboard to successfully complete the task (LE Lundgren et al., 2016). ...
We aimed to determine whether there were any differences in how surfers used their lead and trail limbs when landing two variations of a simulated aerial manoeuvre, and whether technique affected the forces generated at landing. Fifteen competitive surfers (age 20.3 ± 5.6 years, height 178.2 ± 9.16 cm, mass 71.0 ± 10.5 kg) performed a Frontside Air (FA) and Frontside Air Reverse (FAR), while we collected the impact forces, ankle and knee muscle activity, and kinematic data. A principal component analysis (PCA) was used to reduce 41 dependent variables into 10 components. A two-way MANOVA revealed that although there were no limb x aerial variation interactions, surfers generated significantly higher relative loading rates at landing for the trail limb compared to the lead limb (+28.8 BW/s; F(1,303) = 20.660, p < 0.0001, η² = 0.064). This was likely due to the surfers “slapping” the trail limb down when landing, rather than controlling placement of the limb. Similarly, higher relative loading rates were generated when landing the FA compared to the FAR (+23.6 BW/s; F(1,303) = 31.655, p < 0.0001, η² = 0.095), due to less time over which the forces could be dissipated. No relationships between aerial variation or limb were found for any of the kinematic or muscle activity data. Practitioners should consider the higher relative loading rates generated by a surfer’s trail limb and when surfers perform a FA when designing dry-land training to improve the aerial performance of surfing athletes.
... Increases in joint stiffness which have been shown to be caused by load carriage, are thought to transfer up the kinetic chain to other joints [21]. Not only may this predispose candidates to injury in the latter stages of a selection course [22], it may also highlight an injury risk for those who are already in the specialist police role who are working at a high operational tempo. ...
Specialist police tactical teams, like special operations military personnel, are tasked with dangerous, high risk missions which are beyond the scope of general police. Consequently, the selection courses for entry into these teams are physiologically and psychologically demanding. The purpose of this study was to examine the physiological effects of a five-day selection course to aid in candidate preparation and course planning. Measures included body mass, grip strength, sit-and-reach flexibility, and a vertical jump assessment. Eleven candidates finished the selection course with significant decreases in body mass (-2.05 kg, p = 0.006 (95% CI = 3.65-0.45)), grip strength in the right (-14.48 kg, p < 0.001 (95% CI = 21.32-7.64)) and left (-14.27 kg, p < 0.001 (95% CI = 21.89-6.66)) hands and in sit-and-reach flexibility (-6.64 cm, p < 0.001 (95% CI = 9.94-3.33)). No significant decreases in power output or peak jump velocity of 669.77 W (95% CI = 1942.92-603.39) and 0.28 m/s (95% CI = 0.69-0.14) were found and a non-significant, overall increase in vertical jump height of 6.09 cm (95% CI = -6.08 to 18.79) was seen. Decreases in body mass, grip strength and lower limb flexibility are evident in a grueling five-day selection course. Individuals planning on attending these courses should plan for these negative effects and build redundancy into their performance to minimize the effects of fatigue, decrease injury risk and maximize chances of completion.
... 24 previous study reported that a loss of knee flexion and ankle dorsiflexion ROM predisposes for the most prevalent knee pathologies in athletes such as patellar tendinopathy and achilles tendinopathy. 25 However, to date, there is no report indicating an association between injury ratings and restricted knee or ankle ROM in cycling, probably because the measurement of lower-limb ROM is an unusual assessment in cyclists. Reductions in ankle dorsiflexion may influence pedaling mechanics by limiting the ability to pass the leg forwards over the foot, 26 which consequently could cause a greater stress on the knee. ...
BACKGROUND: To describe the lower limb range of motion (ROM) profile in professional road cyclists.
METHODS: Cohort study. One hundred and twenty-one road cyclists volunteered to participate. ROM measurements of passive hip flexion, extension, internal rotation, external rotation, knee flexion and ankle dorsiflexion in dominant and non-dominant limbs were performed using an inclinometer. ROM scores were individually categorized as normal or restricted according to reference values.
RESULTS: Overall, hip flexion was smaller in the non-dominant limb than in the dominant limb (F=12.429, p<0.001), with bilateral differences in male (95% Mean Diff=0.5º to 3.3º) and female cyclists (95% Mean Diff=0.1º to 3.1º). Sex differences were found in hip flexion (F=18.346, p<0.001), hip internal rotation (F=6.030, p=0.016) and ankle dorsiflexion (F=4.363, p=0.039), with males showing smaller ROM than females. Males and females had restricted knee flexion in dominant (males=51.6%; females=42.6%) and non-dominant limbs (males=45.0%; females=39.3%). Ankle dorsiflexion was also restricted in dominant males=38.3%; females=31.1%) and nondominant limbs (males=41.6%; females=34.4%).
CONCLUSIONS: Elite road cyclists showed restricted lower-limb ROM according to reference values. In general, male cyclists showed lower values of ROM than females counterparts. These findings suggest that including specific stretching exercises and resistance training to improve knee and ankle dorsiflexion ROM may prevent muscle imbalances caused by chronic pedalling in professional cyclists.
... At present, only Fong et al. (11) has found a significant correlation between ankle DF ROM and peak vGRF (r = -0.41) in healthy participants. Alternatively, numerous studies have shown no significant association between ankle DF ROM and peak vGRF during landing tasks (14,22,30). As such, it is likely that other factors influence peak vGRF, such as angular velocity for the knee and hip joints at initial ground contact (33) and the eccentric work performed by the knee and hip extensor musculature (34). ...
This study examined the effects of a 4-week ankle-mobility intervention on landing mechanics. Twenty participants with restricted ankle dorsiflexion range of motion (DF ROM) were allocated to either a strength training only (n = 9) or a strength training and ankle mobility program (n = 11). Participants performed a weight-bearing lunge test and bilateral drop-landings before and following the intervention. Normalized peak vertical ground reaction force (vGRF), time to peak vGRF and loading rate were calculated, alongside sagittal-plane initial contact angles, peak angles and sagittal-plane joint displacement for the ankle, knee and hip. Frontal-plane projection angles were also calculated. Following the intervention, only the strength and mobility group improved ankle DF ROM (mean difference = 4.1°, effect size (ES) = 1.00, P = 0.002). A one-way analysis of covariance found group effects for ankle joint angle at initial contact (P = 0.045), ankle (P < 0.001) and hip joint angle at peak flexion (P = 0.041), and sagittal-plane ankle (P < 0.001) and hip joint displacement (P = 0.024) during bilateral drop-landings. Post-hoc analysis revealed that the strength and mobility group landed with greater ankle plantar flexion at initial contact (mean difference = 1.4 ± 2.0˚, ES = 0.46) and ankle dorsiflexion at peak flexion (mean difference = 6.3 ± 2.9˚, ES = 0.74) following the intervention, resulting in greater ankle joint displacement (mean difference = 7.7 ± 4.0˚, ES = 1.00). However, the strength training only group landed with increased peak hip flexion (mean difference = 14.4 ± 11.0˚, ES = 0.70) and hip joint displacement (mean difference = 8.0 ± 6.6˚, ES = 0.44) during post-testing. The findings suggest that changes in landing strategies following the performance of a strength training program are specific to whether restrictions in ankle mobility are considered as part of the intervention.
... Previous landing research has shown that participants typically land with the ankle plantar flexed at IC, both during traditional dry-land landings (ie, drop landings) 26,27 and simulated surfing landings. 28 This plantar flexed ankle position at IC allows these participants to use an additional segment (ie, the foot) to dissipate the impact forces during the landing event. ...
Purpose:
Physical preparation of competitive surfers includes substantial dry-land training. It is currently unknown, however, how closely these exercises replicate surfing manoeuvres performed in the ocean. This study compared the technique features displayed by surfers when landing simulated aerial manoeuvres on land to critical features previously established as necessary for surfers to successfully land aerials in the ocean during competition.
Methods:
Fourteen competitive surfers (age 20.6±5.7 years, height 178.1±9.50 cm, mass 70.6±10.8 kg) were recruited to perform two variations of a simulated aerial task, a Frontside Air (FA) and Frontside Air Reverse (FAR). Joint ranges of motion (ROM), centre of pressure and apparent gaze data were collected during the landing event. Paired t-tests or Wilcoxon Signed Rank tests were used to identify any significant differences in the outcome variables between the two aerial tasks.
Results:
Participants displayed 100% and 60% of the critical features associated with successfully landing a FA and FAR, respectively. In both the simulated FA and FAR, participants landed in 1.0-3.7° of dorsiflexion, moving through significantly less ankle joint ROM in the lead limb during the FAR (p < 0.01). Participants also displayed significantly less knee and hip ROM (p = 0.002-0.048) while landing the FAR compared to the FA.
Conclusion:
The simulated FA and FAR tasks are appropriate training tools for surfers to replicate most of the critical features that a surfer should display to successfully land aerial manoeuvres in the ocean. These tasks therefore enable surfers to practice these complex movements in a controlled environment.
... That is, the ankle angles displayed by the surfers during the standard drop-and-stick landing (lead: 26.9 ± 5.7°, trail: 32.2 ± 5.7°) were consistent with ankle angles reported in previous research investigating non-surfing participants performing a similar landing task(32,70).However, when the surfers performed the surf-specific tasks, such as the trampoline landing with the soft-top surfboard, they exhibited significantly greater plantar flexion of the lead limb ankle at initial contact (lead: 19.6 ± 10.3°, trail: 2.9 ± 11.5°; p ≤ 0.05) and finished the stabilisation period in less dorsiflexion than the lead ankle (lead: 28.4 ± 8.7°, trail: 37.0 ± 8.4°; p ≤ 0.05). Furthermore, when the participants performed the two trampoline tasks, the surfers' ankle positions at initial contact were less plantar flexed when compared to the standard drop-and-stick landing. ...
Forsyth, JR, Riddiford-Harland, DL, Whitting, JW, Sheppard, JM, and Steele, JR. Essential skills for superior wave-riding performance: A systematic review. J Strength Cond Res XX(X): 000-000, 2019-To successfully and safely perform surfing maneuvers, surfers and their coaches need to know how to perform each maneuver correctly. Although some components of the sport are well understood, evidence-based recommendations in the scientific literature on how to perform surfing skills are sparse. The aim of this article was to systematically review the body of literature pertaining to discrete wave-riding skills and characteristics that are associated with the ability of surfers to successfully perform them. Searches of PubMed, SCOPUS, SPORTDiscus with Full-text, and Web of Science were undertaken in January 2019, to identify the most appropriate literature, with secondary searches of reference lists used to create a greater pool of possible articles. The review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P). Ten studies deemed appropriate for review captured data from 299 surfers, who were predominantly competitive (78.3%) and male (58.2%). The average Down and Black Quality Index of the articles was 76.3 ± 8.4%, with these articles focusing on the "pop-up" and landing skills. Performance indicators, such as isometric push-up peak forces, force-plate derived and in-water time to pop-up, relative peak forces generated when landing and time-to-stabilization, were all shown to be related to the physical characteristics of surfers and could affect the ability of surfers to successfully ride a wave. Findings from the studies included in this review suggest that the pop-up and landing exhibit trainable qualities that coaches and athletes can use to improve surfing performance.
... The assessment of ankle dorsiflexion range of motion (DF ROM) in the clinical setting is important because it has been linked to Achilles and patellar tendon injuries (32,44,52). When an athlete lacks sufficient ankle DF ROM, excessive pronation of the foot complex may be necessary to compensate and consequently increase the internal rotation of the tibia, leading Step-down exercise using a resistance band above the knees trying to keep lower limbs aligned (H). ...
The objective of this review is to analyze some of the biomechanical factors involved in the most common running injuries: anterior knee pain, iliotibial band syndrome, Achilles tendinopathy, and medial tibial stress syndrome/tibial stress fracture. Eighteen studies met all inclusion criteria. Results showed that there is little consistent evidence in the literature to connect any biomechanical anomaly to any given running injury, except for female runners with patellofemoral pain who have an increased peak hip adduction angle at stance phase. This review suggests that assessing and treating hip mechanics could help to prevent knee injuries in female runners.
... 8 Some studies have linked changes in range of motion (ROM) in plantar flexion and dorsiflexion in the ankle joint to increased risk of overuse symptoms in the muscle-tendon junction of the calf musculature. 50 Muscle tightness has been linked with decreased ROM, 52 but ankle ROM has improved after the release of myofascial trigger points in the soleus, 17 and these trigger points give referred pain to the Achilles tendon area. 17 Thus, relaxing the calf muscles to improve healing in the damaged Achilles tendon might make sense. ...
Background
Eccentric exercises are the only conservative treatment that has shown good clinical results in studies of Achilles tendinopathy (AT), but success rates vary, indicating the need for alternative treatments. Soft tissue treatments are widely used for AT, but strong scientific evidence is lacking to support those treatments.
Purpose/Hypotheses
This study aimed to determine whether pressure massage to the calf muscles is a useful treatment for AT and to compare this treatment versus an eccentric exercise protocol. Our first hypothesis was that pressure massage treatment is equivalent or superior to eccentric exercises with regard to pain reduction time (ie, pain would be reduced more quickly with pressure massage). The second hypothesis was that pressure massage is equivalent or superior to eccentric exercises with regard to function of the calf muscles.
Study Design
Randomized controlled trial; Level of evidence, 1.
Methods
A total of 60 patients with AT were randomized into 3 groups: group 1 underwent an eccentric exercise protocol, group 2 underwent pressure massage, and group 3 underwent pressure massage and the eccentric exercise protocol. Patients were evaluated with the Icelandic version of the Victorian Institute of Sports Assessment–Achilles questionnaire (VISA-A-IS), an algometer to test the pressure pain threshold (PPT) of the Achilles tendon, tests for ankle range of motion (ROM), and real-time ultrasonographic (US) scanning of tendon thickness and degree of neovascularization. Measurements for VISA-A-IS, PPT, and ROM were taken at 0, 4, 8, 12, and 24 weeks. US scan measurements were taken at 0, 12, and 24 weeks. Mixed-model analysis of variance was used for statistical analysis.
Results
All groups improved when evaluated with VISA-A-IS scores (P < .0001). The pressure massage group improved significantly more than the eccentric exercise group at week 4, which was the only between-group difference. Ankle ROM increased significantly over time (ROM bent knee P = .006 and ROM straight knee P = .034), but no significant difference was found between groups. No significant difference was found in evaluations of PPT or US scan measurements.
Conclusion
Pressure massage is a useful treatment for Achilles tendinopathy. Compared with eccentric exercise treatment, pressure massage gives similar results. Combining the treatments did not improve the outcome.
... Flat foot may lead to excessive ankle eversion, resulting in the onset of Achilles peritendinitis 5) . Excessive extension stress of the triceps muscle was reported due to restricted ankle dorsiflexion, to have resulted in the onset of Achilles peritendinitis 11) . Longitudinal studies have also analyzed the relationship between the onset of Achilles peritendinitis and these foot static alignments 12,13) , suggesting that foot static alignment with flat foot or restrictive ankle dorsiflexion were features leading to the onset of Achilles peritendinitis. ...
[Purpose] To clarify the relationship between movement of the shank relative to the global reference frame (shank angle) while running, and foot alignment factors that lead to the onset of Achilles peritendinitis. [Participants and Methods] This study included 54 healthy male participants. Running at a constant speed was measured by three-dimensional motion analysis. The shank angle at the time of the first peak of vertical ground reaction force and maximum ankle dorsiflexion were analyzed. The magnitude of ankle plantarflexion, inversion, and adduction angle in the propulsive phase as well as static foot alignment (navicular index, and range of ankle dorsiflexion angle) were measured. The relationships between shank angle features and these parameters were investigated. [Results] Outward inclination of the shank occurred at the time of the first peak of vertical ground reaction force and maximum ankle dorsiflexion, with this increase in movement correlating with parameters that increased the risk of Achilles peritendinitis. [Conclusion] These findings suggest that evaluation of the shank angle on the frontal plane while running may be used to estimate the onset of Achilles peritendinitis in clinical practice.
... This is 97 compounded by restrictions in ankle DF ROM also being negatively correlated (r = -0. 27 -98 0.36) with frontal-and transverse-plane kinematic compensations throughout the lower 99 extremity during both unilateral (Whitting, Steele, McGhee & Munro, 2011) and bilateral 100 landings (Malloy, Morgan, Meinerz, Geiser, & Kipp, 2015;Sigward, Ota & Power, 2008). ...
Limited evidence is available concerning ankle dorsiflexion range of motion (DF ROM) and its relationship with landing performance from varying drop heights. The aim of this investigation was to determine the relationship between ankle DF ROM and both kinetic and kinematic variables measured during bilateral drop-landings from 50%, 100% and 150% of countermovement jump height. Thirty-nine participants were measured for their ankle DF ROM using the weight-bearing lunge test, after which five bilateral drop-landings were performed from 50%, 100% and 150% of maximal countermovement jump height. Normalized peak vertical ground reaction force (vGRF), time to peak vGRF and loading rate was calculated for analysis, alongside sagittal-plane initial contact angles, peak angles and joint displacement for the hip, knee and ankle. Frontal-plane projection angles were also calculated. Ankle DF ROM was not related to normalized peak vGRF, time to peak vGRF or loading rate (P > 0.05), regardless of the drop height. However, at drop heights of 100% and 150% of countermovement jump height, there were numerous significant (P < 0.05) moderate to large correlations between ankle DF ROM and initial contact angles (r = −0.34 to −0.40) and peak angles (r = −0.42 to −0.52) for the knee and ankle joint. Knee joint displacement (r = 0.39–0.47) and frontal-plane projection angle (r = 0.37–0.40) had a positive relationship with ankle DF ROM, which was consistent across all drop heights. Ankle DF ROM influences coordination strategies that allow for the management of vGRF during bilateral drop-landings, with alterations in alignment for the knee and ankle joints at both initial contact and peak angles.
... Se ha mostrado en cadáveres que existe una continuidad de la fascia plantar con el paraten- dón del tendón de Aquiles, proporcionando una correlación positiva entre la carga del tendón de Aquiles y la tensión de la fascia plantar. 13 Esta ampliamente aceptado que la disminución de la dorsiflexión de tobillo es uno de los prin- cipales factores de riesgo para desarrollar tanto fascitis 14-18 como otras patologías del miembro inferior (tendinopatía Aquílea [19][20][21] , esguince de tobillo, atrapamiento nervioso en el dorso del pie y metatarsalgia [22][23] , lesiones del ligamen- to cruzado anterior 24 , tendinopatía rotuliana 25 , síndrome de dolor patelofemoral 21,23,26 y Mor- bus Osgood Schlatter 27 ). ...
... As the landing height increases, the ankle angle at IC has been shown to become more plantar-flexed, and ankle energy dissipation and ankle ROM increase [3]. Subjects have been reported to alter ankle joint kinematics and kinetics to set ankle stiffness when performing landing tasks in anticipation of the impact load [18]. This altered ankle landing technique helps maintain the peak dorsiflexion angle under the individual physiological limit [19]. ...
Background:
During landing, the ankle angle at initial contact (IC) exhibits relatively wide individual variation compared to the knee and hip angles. However, little is known about the effect of different IC ankle angles on energy dissipation.
Research question:
The purpose of this study was to investigate the relationship between individual ankle angles at IC and energy dissipation in the lower extremity joints.
Methods:
Twenty-seven adults performed single-leg landings from a 0.3-m height. Kinetics and kinematics of the lower extremity joints were measured. The relationship between ankle angles at IC and negative work, range of motion, the time to peak ground reaction force, and peak loading rate were analyzed.
Results:
The ankle angle at IC was positively correlated with ankle negative work (r = 0.80, R2 = 0.64, p < 0.001) and the contribution of the ankle to total (ankle, knee and hip joint) negative work (r = 0.84, R2 = 0.70, p < 0.001), but the ankle angle was negatively correlated with hip negative work (r = -0.46, R2 = 0.21, p = 0.01) and the contribution of the hip to total negative work (r = -0.61, R2 = 0.37, p < 0.001). The knee negative work and the contribution of the knee to total negative work were not correlated with the ankle angle at IC. The ankle angle at IC was positively correlated with total negative work (r = 0.50, R2 = 0.25, p < 0.01) and negatively correlated with the peak loading rate (r = -0.76, R2 = 0.57, p < 0.001).
Significance:
These results indicated that landing mechanics changed as the ankle angle at IC increased, such that the ankle energy dissipation increased and redistributed the energy dissipation in the ankle and hip joints. Further, these results suggest that increased ankle energy dissipation with a higher IC plantar flexion angle may be a potential landing technique for reducing the risk of injury to the anterior cruciate ligament and hip musculature.
... While previous investigations mainly focused on the adult population [5][6][7]9,13,14], the ankle injury of pediatric and adolescent population has been understudied, especially its risk factors. Identification of risk factors is essential in determining appropriate and effective prevention strategies [15]. ...
Background: Ankle sprain is one of the most common musculoskeletal injuries among young athletes, and there remains a gap in the literature regarding susceptibility to such injuries among physically active youth.
Objective: The primary purpose of this study was to determine the associations between sex, a history of ankle sprain, and ankle range of motion (ROM) in pediatric and adolescent athletes.
Methods: Athletes under the age of 18 years old who presented to a sports injury prevention center underwent ankle ROM measurements including plantarflexion (PF), inversion (IV), and eversion (EV). A two-way analysis of covariance (ANCOVA) was performed to examine effect of sex and a history of ankle sprain on ROMs. Also, a binary logistic regression was performed to investigate variables that are associated with a history of ankle injury.
Results: Among 452 pediatric and adolescent athletes [268 females (13.6±2.3 years old) and 184 males (13.3±2.5 years old)], 128 reported a history of previous ankle sprain. Females demonstrated significantly increased ROMs (PF and IV bilaterally, and right EV) compared to males while there was no effect of a history of ankle sprain on ROMs. Female sex was independently associated with a history of ankle sprain.
Conclusion: There was a strong effect of female sex on ROMs rather than a history of ankle injury history. Additionally, pediatric and adolescent females have greater odds of a history of ankle sprain when compared to their male counterparts.
... Ankle dorsiflexion range of motion (DROM) is often assessed to establish functional ROM of this joint. Ankle mobility is an important factor in influencing performance during squatting, jumping and landing, movements of daily living and balance (1)(2)(3)(4). A number of methods can be used to assess ankle DROM. ...
AIM The aim of this study was to establish if a shank-to foot-length ratio had an influence on the knee-to-wall assessment score.
... The external rotation of the lower limb during the course of concentric exercise did not show any statistically significant differences between the medial and lateral gastrocnemius, but the %MVC of the medial gastrocnemius showed a significant increase when eccentric exercise was performed 12) . In addition, previous studies have reported that separate analyses of medial and lateral gastrocnemius EMG findings reveal that when the dorsiflexion range of motion is narrower, the peak EMG signal is greater in the medial gastrocnemius 14) . This is in accordance with our results, taking into consideration the fact that the ankle range of motion is reduced in patients with Achilles tendinopathy compared with normal people. ...
[Purpose] This study aimed to identify changes in muscle activation by comparing muscle activities of the affected side (AS) and non-affected side (NAS) during eccentric and concentric exercises in runners with unilateral Achilles tendinopathy. [Subjects] The study included 18 participants consisting of men and women with chronic Achilles tendinopathy in a single leg who had more than 1 year of running experience. [Methods] All subjects performed concentric and eccentric exercise with the Achilles tendon moving from full plantar flexion to full dorsiflexion for 8 seconds, and electromyography data was obtained. [Results] All muscles examined showed a significant increase in %maximal voluntary contraction (MVC) with concentric exercise compared with eccentric exercise. Compared with the NAS, the AS showed significant increases in %MVC of the rectus femoris, tibialis anterior, and lateral gastrocnemius. All interaction effects of exercise methods and injuries showed statistically significant changes. [Conclusion] Runners with Achilles tendinopathy show increases in medial gastrocnemius activity when performing eccentric exercise.
... 18 This large KW may further contribute to increased ability to reduce the rPF in landings, 15 although the literature is somewhat divergent regarding this effect of ankle range of motion. 27 Further studies are therefore warranted to determine whether this is a correct assumption. In addition, general strength, as measured using IMTP in this study, is an important contributor to safety in landings because the lower-extremity muscles are responsible for absorbing the oftenvery-high compression forces. ...
This study develops and evaluates a multi-factorial model, based on landing performance, to estimate injury risk for surfing athletes.
Five measures were collected from 78 competitive surfing athletes and then used to create a model to serve as a screening tool for landing tasks and potential injury risk. In the second part of the study, the model was evaluated using junior surfing athletes (n=32) with a longitudinal follow-up of their injuries over 26 weeks. Two models were compared based on the collected data, and magnitude based inferences were applied to determine the likelihood of differences between injured and non-injured groups.
The study resulted in a model based on five measures: (i) ankle dorsiflexion range of motion, (ii) isometric mid-thigh pull lower body strength, (iii) time to stabilisation during a drop and stick (DS) landing, (iv) relative peak force during a DS landing, and (v) frontal plane DS landing video analysis; for male and female professional surfers, and male and female junior surfers. Evaluation of the model showed that a scaled probability score was more likely to detect injuries in junior surfing athletes, and reported a correlation of r=0.66, p=0.001 with a model of equal variable importance. The injured (n=7) surfers had a lower probability score (0.18 ± 0.16) compared to the non-injured group (n=25, 0.36 ± 0.15), with 98% likelihood, Cohen's d=1.04.
The proposed model seems sensitive, easy to implement and interpret. Further research is recommended to show full validity potential adaptations for other sports.
... Lower extremity joint mechanics are also frequent targets of investigation since these joints absorb energy upon landing (Fong, Blackburn, Norcross, McGrath, & Padua, 2011;Gross & Nelson, 1988;Kovacs, Tihanvi, Devita, Racz, Barrier, & Hortobagvi, 1999;Kulig, Fietzer, & Popovich, 2011;McNair, Prapavessis, & Callender, 2000;McNitt-Gray, 1993;Self & Paine, 2001;Whitting, Steele, McGhee, & Munro, 2011;Yeow, Lee, & Goh, 2009;Yu, Lin, & Garrett, 2006). The stiffness of these joints, differences in joint range of motion and angular velocity under a given force or demand, appears to play a role in how these vGRFs are attenuated. ...
The ankle joint's role in shock absorption during landing has been researched in many studies, which have found that landing with higher amounts of plantarflexion (PF) results in lower peak vertical ground reaction forces and loading rates. However, there has not yet been a study that compares drop landings within participants along a quantitative continuum of PF angles. Using a custom-written real-time feedback program, participants adjusted their ankles to an instructed PF angle and dropped onto two force platforms. For increasing PF, peak ground reaction force and peak loading rate during weight acceptance decreased significantly. The hip's contribution to peak support moment decreased as PF at initial contact increased up to 30°. The ankle and knee contributions increased over this same continuum of PF angles. There appears to be no optimal PF angle based on peak ground reaction force and loading rate measurements, but there may be an optimum where joint contributions to peak support moment converge and the hip moment's contribution is minimised.
Although the stability and shape of joint surfaces allows for fluid joint motion and terrain adaptation, the tendons crossing the ankle joint are directly responsible for driving the movement that is so crucial for standing, balancing, squatting, walking, running, cutting, climbing, jumping, lunging, kicking, spinning, and dancing. While there are several groups of tendons crossing the ankle joint with unique functions and pathologic considerations, tendon disorders share many common features. Understanding normal tendon macro and microstructure and biomechanics provides basis for their disorder from overuse, injury, and disease. The most frequently encountered tendon pathologies at the ankle excluding the posterior tibialis (beyond the scope of this chapter) but including the tibialis anterior, Achilles and peroneal tendinopathies are discussed with a focus on clinical and radiographic presentations. Treatment strategies for various stages of disease, dysfunction, and injury reveal a myriad of non-surgical and operative approaches that facilitate the health care providers’ ability to maintain the lower extremity’s mobility and performance.KeywordsTendinopathyTendonitisTibialis anterior tendinopathyAchilles tendinopathyPeroneal tendinopathy
There seems to be no information on the incidence of injury and associated risk factors for academy football players in Ghana. We determine the risk factors associated with match and training injuries among male football players at an academy in Ghana. Preseason measurements of players’ height, weight, and ankle dorsiflexion (DF) range of motion (ROM) were measured with a stadiometer (Seca 213), a digital weighing scale (Omron HN-289), and tape measure, respectively. The functional ankle instability (FAI) of players was measured using the Cumberland Ankle Instability Tool (CAIT), and dynamic postural control was measured with the Star Excursion Balance Test. Injury surveillance data for all injuries were collected by resident physiotherapists throughout one season. Selected factors associated with injury incidence were tested using Spearman’s rank correlation at a 5% significance level. Age was negatively associated with overall injury incidence (r = − 0.589, p = 0.000), match (r = − 0.294, p = 0.008), and training incidence (r = − 0.314, p = 0.005). Previous injury of U18s was associated with training injuries (r = 0.436, p = 0.023). Body mass index (BMI) was negatively associated with overall injury incidence (r = − 0.513, p = 0.000), and training incidence (r = − 0.395, p = 0.000). CAIT scores were associated with overall injury incidence (n = 0.263, p = 0.019) and match incidence (r = 0.263, p = 0.029). The goalkeeper position was associated with match incidence (r = 0.241, p = 0.031) while the U16 attacker position was associated with training incidence. Exposure hours was negatively associated with overall injury incidence (r = − 0.599, p = 0.000). Age, BMI, previous injury, goalkeeper and attacker positions, ankle DF ROM, and self-reported FAI were associated with injury incidence among academy football players in Ghana.
After recently accepting an offer to retire, I have taken the opportunity to reflect on long-term lessons learned throughout my 40-year career as a biomechanist in academia. These lessons formed the basis of my 2021 Geoffrey Dyson Lecture and are summarised within this article. Most of these lessons are targeted at early career researchers, although my recent transition into retirement revealed some unexpected lessons that apply to senior academics. The lessons presented relate to the need to be passionate and persistent about your research, the importance of being unique and embracing failure as a mentor, as well as running with opportunities that arise. Appreciating that a career takes time to evolve, strategies to nurture a committed and supportive research team, the importance of committing to a professional society, and the need to be kind to yourself are also discussed. Why so few women receive career awards in biomechanics and when should academics retire are also addressed. I hope that highlighting lessons learned over an academic career as a biomechanist, combined with suggested practical strategies to thrive in academia, ensure academics can savour a fulfiling career in biomechanics while producing high-quality research into the future.
Background
Larger ankle dorsiflexion (DF) is required when walking on inclined surfaces. Individuals with limited DF range of motion (ROM) may experience greater tissue stress on sloped surfaces and walk in altered gait patterns compared to the those with normal DF ROM.
Research question
Would the individuals with limited DF ROM walk with distinctive ankle DF patterns compared to those with normal DF ROM on the inclined surfaces?
Methods
Ten Limited DF ROM (passive ROM=35.3±2.7°) and nine Normal DF ROM (passive ROM=46.4±4.2°) participants walked on a treadmill at five slope angles (0°, 5°, 10°, 15°, 20°) for 2 minutes at a self-selected speed. The peak DF angles and the peak myoelectric activity levels of the tibialis anterior (TA) and soleus (SOL) muscles were quantified during the swing and stance phases of each walking trial, and they were compared between the two groups.
Results
Participants with limited DF ROM walked with smaller peak DF (3.1° at 0° slope ~ 8.4° at 20° slope) and greater peak TA activity in swing than those of the Normal ROM participants (3.4° ~ 12.2°), with significant differences at 20° slope. The peak DF angle in stance (Limited: 9.6° ~ 19.0°; Normal: 10.1° ~ 21.0°) did not differ between the two groups at all slopes, but the peak activity of the SOL muscle was significantly greater for the Limited group at slopes of 10° and higher.
Significance
Study results indicate that incline walking could be more challenging to the individuals with limited DF ROM as they need to approach and push-off the sloped surfaces with more efforts of the dorsiflexor and the plantar flexor muscles, respectively. Prolonged walking on inclined surfaces may produce faster development of muscle fatigue or tissue damage than those with normal DF ROM.
vonGaza, GL, and Chiu, LZF. Comparison of alternative methods to improve weight-bearing sagittal plane anterior leg rotation. J Strength Cond Res 35(12): 3315-3321, 2021-Promoting rearfoot plantar flexion may permit greater sagittal plane anterior leg rotation in weight-bearing tasks. Anterior leg rotation, where the proximal tibia translates forward, is required for tasks such as squatting and landing from a jump. Twenty-eight individuals with less than 25° anterior leg rotation during a weight-bearing lunge test were enrolled and randomly assigned to self-massage and stretching only (n = 15; 14 subjects retained) or self-massage and stretching plus gastrocnemius exercise (n = 13). Anterior leg rotation was assessed during a weight-bearing lunge test and a partial squat; 95% confidence interval (95% CI) of the change score and Cohen's d effect size were calculated. Anterior leg rotation in the weight-bearing lunge increased in the self-massage and stretching only (left: 95% CI [2.1°-5.4°], d = 1.14; right: 95% CI [2.3°-6.0°], d = 1.22) and self-massage and stretching plus gastrocnemius exercise (left: 95% CI [2.3°-7.5°], d = 1.71; right: 95% CI [4.2°-8.6°], d = 1.48) groups. There were no changes in anterior leg rotation in the partial squat for self-massage and stretching only (left: 95% CI [-1.2° to 2.5°], d = 0.15; right: 95% CI [-0.5° to 2.6°], d = 0.24) or self-massage and stretching plus gastrocnemius exercise (left: 95% CI [-0.2° to 4.8°], d = 0.55; right: 95% CI [-0.2° to 4.0°], d = 0.59) groups. Increases in anterior leg rotation in the weight-bearing lunge may be due to decreased passive stiffness in the plantar structures.
PURPOSE: The purpose of this study was to compare the vastus lateralis (VL) architecture and exercise biomechanics indices during drop landing in young football players.METHODS: Fifteen young football players were divided into a long vastus lateralis muscle fascicle length group (LFG, n=8) and short vastus lateralis muscle fascicle length group (SFG, n=7). All of the participants performed drop landing onto the ground reaction force plate from a platform 30 cm high. The muscle activities of the VL, tibialis anterior (TA), and gastrocnemius (GCM), angular velocity, and ground reaction force in the ankle, knee, and hip joints were measured during drop landing.RESULTS: The VL muscle activity (p=.032), ankle ground contact angle (p=.027), ankle maximum flexion angle (p=.014), knee maximum flexion angle (p=.007), and ground reaction force per body weight (p=.032) were significantly higher in the LFG than in the SFG. Muscle activity of the TA (p=.017), ankle (p=.033), and hip (p=.045) time to stability and the ground reaction force time to stability (p=.043) were significantly lower in the LFG than in the SFG. Muscle activity of the GCM (p=.053) and knee time to stability (p=.057) tended to be lower in the LFG than in the SFG.CONCLUSIONS: These results confirmed that muscle activity, angular velocity, and ground reaction force variables during drop landing are affected by the VL muscle fascicle length in young football players.
Introducción. La auto-liberación miofascial es una intervención popularmente utilizada por los profesionales de la rehabilitación, el acondicionamiento físico y el deporte para favorecer la recuperación post-lesión y el rendimiento físico-técnico deportivo. Diferentes estudios han demostrado la eficacia del efecto agudo del foam-rolling (FR) con duraciones muy amplias (80-180 s) sobre el incremento de la extensibilidad muscular en el calentamiento. Sin embargo, no se ha encontrado ningún trabajo que analice el efecto agudo con una duración más real del contexto físico-deportivo sobre el sóleo. El objetivo del presente estudio fue determinar el efecto agudo de un protocolo corto de FR sobre la extensibilidad del sóleo en estudiantes físicamente activos.
Material y métodos: Treinta y uno adultos físicamente activos (edad: 22,7±1,8 años; peso: 73,6±11,6 kg; altura: 1,76±0,09 cm). En la pierna dominante de los participantes fue aplicado el protocolo FR (1 x 30 s), mientras que la pierna no dominante fue designada como grupo control. El rango de movimiento (ROM) de dorsi-flexión del tobillo para el sóleo de ambas extremidades fue valorado antes e inmediatamente después de la intervención de FR siguiendo la metodología de protocolo ROM-SPORT. Se aplicó una prueba t-test student para observar posibles de diferencias entre la pre- y post-intervención de FR. Se calculó la magnitud del tamaño del efecto de Cohen de todos los resultados, y la magnitud del efecto fue interpretado de acuerdo con los criterios de Hopkins, Marshall, Batterham & Hanin (2009).
Resultados. El aumento promedio del grupo FR fue de 3º con un tamaño del efecto moderado (p=0,000; d=0,66). El grupo control mostró un aumento significativo de 0,8º (p=0,036), pero el tamaño del efecto fue trivial (d=0).
Conclusiones. Los resultados sugieren que 30 s de FR es una estrategia real y efectiva para aumentar la extensibilidad del sóleo y el rango de movimiento de dorsi-flexión del tobillo durante el calentamiento.
Context: Ankle dorsiflexion range of motion (DF ROM) has been associated with a number of kinematic and kinetic variables associated with landing performance that increase injury risk. However, whether exercise-induced fatigue exacerbates compensatory strategies has not yet been established.
Objectives: i) explore differences in landing performance between individuals with restricted and normal ankle DF ROM, and ii) identify the effect of fatigue on compensations in landing strategies for individuals with restricted and normal ankle DF ROM.
Design: Cross-sectional.
Setting: University research laboratory.
Patients or Other Participants: 12 recreational athletes with restricted ankle DF ROM (restricted group) and 12 recreational athletes with normal ankle DF ROM (normal group).
Main Outcome Measure(s): Participants performed five bilateral drop-landings, before and following a fatiguing protocol. Normalized peak vertical ground reaction force (vGRF), time to peak vGRF and loading rate were calculated, alongside sagittal plane initial contact angles, peak angles and joint displacement for the ankle, knee and hip. Frontal plane projection angles were also calculated.
Results: At baseline, the restricted group landed with significantly less knee flexion (P = 0.005, effect size [ES] = 1.27) at initial contact and reduced peak ankle dorsiflexion (P < 0.001, ES = 1.67), knee flexion (P < 0.001, ES = 2.18) and hip flexion (P = 0.033, ES = 0.93) angles. Sagittal plane joint displacement was also significantly less for the restricted group for the ankle (P < 0.001, ES = 1.78), knee (P < 0.001, ES = 1.78) and hip (P = 0.028, ES = 0.96) joints.
Conclusions: These findings suggest individuals with restricted ankle DF ROM adopt different landing strategies than those with normal ankle DF ROM. This is exacerbated when fatigued, although the functional consequences of fatigue on landing mechanics in individuals with ankle DF ROM restriction are unclear.
Background: To describe the lower limb range of motion (ROM) profile in professional road cyclists.
Methods: Cohort study. One hundred and twenty-one road cyclists volunteered to participate. ROM measurements of passive hip flexion, extension, internal rotation, external rotation, knee flexion and ankle dorsiflexion in dominant and non-dominant limbs were performed using an inclinometer. ROM scores were individually categorized as normal or restricted according to reference values.
Results: Overall, hip flexion was smaller in the non-dominant limb than in the dominant limb (F=12.429, p<0.001), with bilateral differences in male (95% Mean Diff=0.5º to 3.3º) and female cyclists (95% Mean Diff=0.1º to 3.1º). Sex differences were found in hip flexion (F=18.346, p<0.001), hip internal rotation (F=6.030, p=0.016) and ankle dorsiflexion (F=4.363, p=0.039), with males showing smaller ROM than females. Males and females had restricted knee flexion in dominant (males=51.6%; females=42.6%) and non-dominant limbs (males=45.0%; females=39.3%). Ankle dorsiflexion was also restricted in dominant males=38.3%; females=31.1%) and nondominant limbs (males=41.6%; females=34.4%).
Conclusions: Elite road cyclists showed restricted lower-limb ROM according to reference values. In general, male cyclists showed lower values of ROM than females counterparts. These findings suggest that including specific stretching exercises and resistance training to improve knee and ankle dorsiflexion ROM may prevent muscle imbalances caused by chronic pedalling in professional cyclists.
Background:
The aim of this study was to investigate the effects of basketball match-play on ankle dorsiflexion range of motion (ROM) and countermovement (CMJ) performance, and their association with internal match load.
Methods:
Thirty semi-professional basketball players participated in this study. Ankle dorsiflexion ROM and bilateral CMJ performance were evaluated before (pre- match) and immediately after match-play (post-match). In addition, ankle dorsiflexion ROM was measured 48h post-match. Furthermore, for each player, the ankle dorsiflexion ROM scores were categorized as normal or restricted according to previously reported reference values (>2 cm change from baseline pre-match to post-match and to 48h post- match).
Results:
Ankle dorsiflexion ROM was increased post-match from pre-match in dominant and non-dominant limbs (Most likely small) and decreased 48h post-match (Most likely moderate) compared with immediately post-match measures in both limbs. Approximately 20% of all players showed restricted ankle dorsiflexion ROM values 48h post-match. CMJ performance was higher post-match than pre-match.
Conclusions:
Ankle dorsiflexion ROM is still reduced 48h after a competitive basketball match in semi-professional basketball players. The implementation of specific recovery strategies aiming at minimizing a decrease in ankle dorsiflexion after a match might be considered to reduce the likelihood of ankle injury.
Objetivo: Detectar futbolistas con alto riesgo de lesión y estudiar la relación entre la FDT y las asimetrías del miembro inferior mediante el crossover hop test for distance.
Métodos: Quince jugadores de un equipo amateur de fútbol participaron en el estudio. En cada uno de ellos se midió la flexión dorsal de ambos tobillos y la distancia alcanzada en el crossover hop test for distance. Para la medición de la flexión dorsal del tobillo (FDT) se utilizó un inclinómetro en posición weight-bearing. El crossover hop test for distance se llevó a cabo de acuerdo al procedimiento estándar descrito en otros estudios.
Para el análisis de la relación entre FDT y crossover hop test for distance se utilizó el coeficiente de correlación de Pearson tras comprobar la distribución normal de las variables.
Resultados: Cuatro jugadores mostraron una dorsiflexión del tobillo igual o inferior a 36,5º. Tres presentaban una asimetría superior al 15% en el hop test. El análisis estadístico no demostró correlación entre la FDT y los resultados obtenidos en el hop test.
Conclusiones: El estudio permitió seleccionar sujetos con alto riesgo de lesión. La FDT no está relacionada con el resultado del hop test ni con el IA.
Objetive: To detect high injury risk football players and to study the relationship between the ankle dorsiflexion range of motion and assymmetrys of the lower limb.
Methods: Fifteen football players from amateur football team were enroled in the study. Dorsiflexion range of motion and the distance reached in the crossover hop test were measured in all of them. Inclinometer was used to measure the ankle dorsiflexion in weigth-bearing position. The crossover hop test was performed according to standars procedures.
In order to check the relationship between ankle dorsiflexion and crossover hop test, Pearson correlation coefficient was used in the statictical analysis.
Results: An ankle dorsiflexión under 36,5º was observed in four players. Assymmetrys over 15% in the crossover hop test was found in three players. The statical analysis did not show correlation between the ankle dorsiflexion and the results obtained in the hop test
Conclusions: This study helped to detect high injury risk football players. The ankle dorsiflexion is not relationed with the hop test results.
Background:
Passive ankle dorsiflexion range of motion (DROM) measures have been identified as a risk factor for injury during landings. However, passive measurements might not be indicative of dynamic ankle movement, whereas a weightbearing ROM might be a better tool when evaluating movement. The purpose of this study was to investigate the relationship between weightbearing DROM and sagittal plane landing mechanics in a single leg drop jump task.
Methods:
73 male athletes (22.1 ± 3.9 years old, height 186.2 ± 11 cm, and weight 100.2 ± 21.8 kg) performed bilateral modified-lunge tasks and bilateral single leg drop jump landings while 3D kinematic data were collected. Hip, knee, and ankle joint angles were calculated at initial contact (IC) maximum knee flexion (MKF), and total excursion (TE) during a single leg drop jump landing.
Results:
No bilateral differences in DROM and single leg landing mechanics existed. Decreased ankle DROM was correlated to decreased ankle dorsiflexion at MKF (p=0.00) and TE (p=0.00) for both dominant and non-dominant limbs. Decreased ankle DROM was also correlated to decreased knee flexion at IC (p=0.00), MKF(p=0.00), and TE (p=0.1), for both dominant and non-dominant limbs. Ankle DROM correlated to hip flexion at MKF (r=0.25) and TE (r=0.30) in the dominant limb.
Conclusions:
Restrictions in DROM may contribute to a stiff landing with less flexion at the ankle and knee. These findings may be useful in designing training programs aimed at increasing DROM in order to improve an athlete's landing mechanics and decrease risk of injury.
Prevention of musculotendinous injuries is an idealistic goal which, while it may not be possible, is worth striving for. Athletes and individuals engaged in dynamic activity are subject to the risk of sustaining many forms of injury including to the muscles and tendons. While these injuries are not life-threatening and are rarely permanently disabling, they do impose a limitation on the ability of the individual to perform competitively and are frequently recurrent if not managed adequately. There are many anatomical, biomechanical, physical and chemical factors which have been shown to be associated with an increased risk of musculotendinous injury, but few have a direct cause and effect relationship, and even fewer have any proof of efficacy in the role of prevention.
Military static-line parachuting is a highly tactical and hazardous activity, with a well-documented injury risk. Due to the high impact forces and rapid rate of loading when a parachutist lands, injuries most frequently occur to the lower limbs and the trunk/spine, with ankle injuries accounting for between 30 and 60 % of all parachuting injuries. Although military static-line parachuting injuries can be sustained at any time between the paratrooper attempting to leave the aircraft until they have landed and removed their harness, most injuries occur on landing. Throughout the world, various landing techniques are taught to paratroopers to reduce the risk of injury, by enabling parachute landing forces to be more evenly distributed over the body. In this chapter, we review research associated with static-line military parachuting injuries, focusing on injuries that occur during high-impact landings. We summarize literature pertaining to strategies for military paratroopers to land safely upon ground contact, especially when performing the parachute fall landing technique. Recommendations for future research in this field are provided, particularly in relation to the parachute fall landing technique and training methods. Ultimately, any changes to current practice in landing technique, how it is taught, and whether protective equipment is introduced, should be monitored in well controlled, prospective studies, with the statistical design accounting for the interaction between the variables, to determine the effect of these factors on injury rates and paratrooper performance. This will ensure that evidence-based guidelines can be developed, particularly in relation to landing technique and how this is trained, in order to minimize injuries associated with landings during military static-line parachuting in subsequent training and tactical operations.
Background:
Clinicians use the lunge position to assess and treat restricted ankle dorsiflexion. However, the individual forefoot and rearfoot contributions to dorsiflexion and the potential for abnormal compensations are unclear. The purposes of this case-control study were to 1) compare single- (representing a clinical lunge position measure) versus multi-segment contributions to dorsiflexion, and 2) determine if differences are present in patients with tendinopathy.
Methods:
32 individuals (16 with insertional Achilles tendinopathy and 16 age- and gender-matched controls) participated. Using three-dimensional motion analysis, the single-segment model was defined as tibial inclination relative to the whole foot. The multi-segment model consisted of rearfoot (tibia relative to calcaneus) and forefoot (1st metatarsal relative to calcaneus) motion. Two-way (kinematic model and group) analyses of variance were used to assess differences in knee bent and straight positions. Associations between models were tested with Pearson correlations.
Findings:
Single-segment modeling resulted in ankle DF values 5° greater than multi-segment modeling that isolated rearfoot dorsiflexion for knee bent and straight positions (P<0.01). Compared to controls, the tendinopathy group had 10° less dorsiflexion with the knee bent (P<0.01). For the tendinopathy group, greater dorsiflexion was strongly associated with greater rearfoot (r=0.95, P<0.01) and forefoot (r=0.81, P<0.01) dorsiflexion. For controls, dorsiflexion was strongly associated with rearfoot (r=0.87, P<0.01) but not forefoot dorsiflexion (r=0.23, P=0.39).
Interpretation:
Clinically used single-segment models of ankle dorsiflexion overestimate rearfoot dorsiflexion. Participants with insertional Achilles tendinopathy may compensate for restricted and/or painful ankle dorsiflexion by increased lowering of the medial longitudinal arch (forefoot dorsiflexion) with the lunge position.
Hurdling is one of the top athletic games with high injury risks, especially the Achilles tendon injury. The purpose of the study was to quantify the Achilles tendon strains using a biomechanical simulation approach, which incorporate motion capture technique and musculoskeletal modeling. The finding indicates that the main muscles of Achilles tendon, gastronomic and soleus, change greatly in muscle length during the hurdling takeoff. The peak angle of the knee and angle was observed at the end of foot touching phase. The results obtained in this study can serve as a basis for further research on Achilles tendon rupture.
To examine the evidence for effect of restricted ankle dorsiflexion range of motion on lower-extremity landing mechanics.
Literature review.
Systematic search of the literature. Articles critiqued by two reviewers.
Six studies were identified that investigated the effect of restricted DF ROM on landing mechanics. Overall, results suggest that landing mechanics are altered with restricted DF ROM, but studies disagree as to the particular mechanical variables affected.
There is evidence that restricted dorsiflexion range of motion may alter lower-extremity landing mechanics in a manner, which predisposes athletes to injury. Interpretation of results was made difficult by the variation in landing tasks investigated and the lack studies investigating sport-specific landing tasks. The focus of studies on specific mechanical variables rather than mechanical patterns and the analysis of pooled data in the presence of different compensation strategies between participants also made interpretation difficult. These areas require further research.
Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
Although decreased dorsiflexion range of motion (DROM) is linked to ankle inversion sprains and other lower limb injuries, the mechanisms underlying these links are not well understood. The purpose of this study was to examine the relationships between DROM and the ankle dorsiflexion and inversion, and the foot progression angles during a sidestep cutting maneuver. Nineteen healthy subjects participated in this study. The loaded DROM in a flexedknee position was measured. The foot and ankle motions were assessed during the sidestep cutting maneuver using a 3D motion analysis system. The low DROM group displayed smaller dorsiflexion and inversion angles, and greater external foot rotation, and performed the task using a significantly greater percent of their DROM than the high DROM group during the sidestep cutting maneuver. In addition, the smaller DROM was associated with smaller dorsiflexion angles, greater external foot rotation, and greater maximum dorsiflexion angles as a percentage of DROM during the sidestep cutting maneuver. The decreased DROM may prevent the ankle from becoming stable during the sidestep cutting maneuver, therefore the ankle may be vulnerable position to an inversion sprain. The kinematic patterns displayed by individuals with a decreased DROM may be a compensatory strategy for dorsiflexion deficits, which may be associated with ankle and knee injuries.
Motion of a reduced quantity has been referred to as 'equinus' and the widely accepted theory is that when equinus is present, an abnormal foot function occurs. For normal foot function and human ambulation the amount of ankle joint dorsiflexion required is claimed to be 10 degrees. The main purpose of this study was to determine and investigate this arbitrary figure of 10 degrees.
Fourteen normal adult subjects with a normal range of motion at the ankle joint and no known gait abnormalities took part in the study. Predetermined suitable anatomical landmarks were marked by reflective skin markers. Data was collected at a frequency of 120Hz using a three-dimensional opto electronic motion analysis system and the three-dimensional co-ordinates were smoothed using a Butterworth filter (Fc = 7Hz) and analysed. All foot angles were expressed relative to the sub talar neutral position and were expressed as joint co-ordinate system (JCS) angles.
Results indicated a ankle joint dorsiflexion value of between 12 and 22 degrees with a wide variation between subjects (Coefficient of Multiple correlation (CMC) values 0.723–0.992).
The results appear to show ankle joint dorsiflexion in normal subjects is greater than the value traditionally espoused by clinicians for walking. This is as a result of the anatomical basis on which measurements are currently made. Although, this may have clinical implications in terms of orthotic prescriptions, more research is needed to determine the effect of terrain, footwear and muscle length on the measurements.
Despite anecdotal evidence linking overpronation to the onset of Achilles tendinopathy (AT), there is little conclusive evidence of a particular movement pattern of the lower extremity associated with this injury. Therefore, the objective of the present study was to observe differences in the kinematic profiles of healthy runners (CON) and runners with mid-portion Achilles tendinopathy (ATG).
In this cross-sectional analysis, 48 male height and weight matched subjects were invited to participate: 27 with mid-portion Achilles tendon pain and 21 asymptomatic controls. Subjects underwent lower extremity clinical examination, then ran barefoot for 10-trials at a self-selected pace. A 3D motion capture system analysed tri-plane kinematic data for the lower extremity.
The ATG displayed significantly greater sub-talar joint eversion displacement during mid-stance of the running gait (13 +/- 3 degrees vs. 11 +/- 3 degrees; p = 0.04). Trends were observed such that the ATG showed lower peak dorsiflexion velocity (300 +/- 39 degrees/s vs. 330 +/- 59 degrees/s; p = 0.08) and greater overall frontal plane ankle joint range of motion (45 degrees +/- 7 vs. 41 degrees +/- 7; p = 0.09).
We found an increase in eversion displacement of the sub-talar joint in runners with Achilles mid-portion tendinopathy. Based on the findings from this study, there is evidence that devices used to control sub-talar eversion may be warranted in patients with Achilles mid-portion tendinopathy who demonstrate over-pronation during mid-stance of the running gait.
The complexity of its anatomy coupled with the biomechanics of the Achilles tendon may explain the frequency of injury to this structure. Its unique characteristic of the muscle crossing three joints (knee, ankle, and subtalar joints) makes it more susceptible to injury than muscles that span a single joint. A better understanding of the contributing pathologic conditions associated with functional shortening of the gastroc-soleus complex and its effects on the normal biomechanics of the foot and ankle may improve the treatment of the many and varied pathologies that occur within the tendon itself and the associated abnormalities that occur with a tight Achilles tendon.
To characterise injuries sustained in basketball and netball that result in hospital admission and to compare the profiles of injury between the two sports.
Population-based retrospective descriptive epidemiological study using data from the National Hospital Morbidity Database, July 2000 to June 2004.
Patients discharged from a public or private hospital with basketball or netball codes as the "activity when injured".
There were 5090 basketball-related hospital admissions (mean patient age, 22.2 [SD, 10.7] years; 71.5% male) and 4596 netball-related admissions (mean patient age, 26.3 [SD, 10.9] years; 88.9% female). Fractures were the most common injury (46.8% [2384] of basketball-related and 29.5% [1358] of netball-related admissions), with the forearm and hand or wrist the most common fracture sites. The participant-based forearm fracture hospitalisation rate (5 + years age group) peaked in the 5-14-years age group. Anterior cruciate ligament rupture was the most common diagnosis, accounting for 760 (16.5%) netball-related admissions (mean [SD] age, 26.7 [8.4] years) and 354 (7.0%) basketball-related admissions (mean age, 25.5 [7.9] years). Achilles tendon injury accounted for 732 (15.9%) netball-related admissions (mean age, 35.2 [7.5] years) and 381 (7.5%) basketball-related admissions (mean age, 35.8 [7.8] years).
The high rates of anterior cruciate ligament rupture and Achilles tendon injury resulting in hospital admission and their long-term consequences impact extensively on the individual and the community. The common injuries sustained in basketball and netball were strongly age-related.
Overuse disorders of tendons, or tendinopathies, present a challenge to sports physicians, surgeons, and other health care professionals dealing with athletes. The Achilles, patellar, and supraspinatus tendons are particularly vulnerable to injury and often difficult to manage successfully. Inflammation was believed central to the pathologic process, but histopathologic evidence has confirmed the failed healing response nature of these conditions. Excessive or inappropriate loading of the musculotendinous unit is believed to be central to the disease process, although the exact mechanism by which this occurs remains uncertain. Additionally, the location of the lesion (for example, the midtendon or osteotendinous junction) has become increasingly recognized as influencing both the pathologic process and subsequent management.
The mechanical, vascular, neural, and other theories that seek to explain the pathologic process are explored in this article. Recent developments in the nonoperative management of chronic tendon disorders are reviewed, as is the rationale for surgical intervention. Recent surgical advances, including minimally invasive tendon surgery, are reviewed. Potential future management strategies, such as stem cell therapy, growth factor treatment, and gene transfer, are also discussed.
To determine the rate of ankle injury and examine risk factors of ankle injuries in mainly recreational basketball players.
Injury observers sat courtside to determine the occurrence of ankle injuries in basketball. Ankle injured players and a group of non-injured basketball players completed a questionnaire.
A total of 10 393 basketball participations were observed and 40 ankle injuries documented. A group of non-injured players formed the control group (n = 360). The rate of ankle injury was 3.85 per 1000 participations, with almost half (45.9%) missing one week or more of competition and the most common mechanism being landing (45%). Over half (56.8%) of the ankle injured basketball players did not seek professional treatment. Three risk factors for ankle injury were identified: (1) players with a history of ankle injury were almost five times more likely to sustain an ankle injury (odds ratio (OR) 4.94, 95% confidence interval (CI) 1.95 to 12.48); (2) players wearing shoes with air cells in the heel were 4.3 times more likely to injure an ankle than those wearing shoes without air cells (OR 4.34, 95% CI 1.51 to 12.40); (3) players who did not stretch before the game were 2.6 times more likely to injure an ankle than players who did (OR 2.62, 95% CI 1.01 to 6.34). There was also a trend toward ankle tape decreasing the risk of ankle injury in players with a history of ankle injury (p = 0.06).
Ankle injuries occurred at a rate of 3.85 per 1000 participations. The three identified risk factors, and landing, should all be considered when preventive strategies for ankle injuries in basketball are being formulated.
To record the incidence of lower limb injuries (acute and overuse syndromes) in Greek artistic gymnasts in relation to the event and exercise phase.
A total of 162 gymnasts (83 male and 79 female athletes) participating in the Greek artistic gymnastic championships were observed weekly for the 1999-2000 season.
Ninety three (61.6%) acute injuries and 58 (38.4%) overuse syndromes were recorded. The most common anatomical location was the ankle (69 cases, 45.7%), followed by the knee (40 cases, 26.5%). The rate of mild injuries was 26.6% (25 cases), that of moderate injuries was 44% (41 cases), and that of major injuries was 29% (27 cases). The incidence of injury to the ankle and knee was significantly higher in the floor exercise, especially during the landing phase, than in the other events.
By its nature, gymnastics predisposes to acute injuries, but up to 75% are mild or moderate. Special attention should be paid to the floor exercise, especially the landing phase.
OBJECTIVE: To compare vertical ground reaction forces among gymnasts and recreational athletes during drop landings from 30-, 60-, and 90-cm heights. DESIGN AND SETTING: Two subject groups, intercollegiate gymnasts and college-aged recreational athletes, participated in this study. Subjects completed 10 landing trials onto a force platform at each height. SUBJECTS: Ten female competitive gymnasts (height = 1.57 +/- 0.02 m, mass = 55.4 +/- 7.3 kg) and 10 female recreational athletes (height = 1.63 +/- 0.06 m, mass = 59.6 +/- 4.9 kg) volunteered for this study. MEASUREMENTS: Measurements of first peak-force magnitude (F1), time to F1 (T1), impulse to F1, second peak-force magnitude (F2), time to F2 (T2), and impulse to F2 were compiled to describe the ground reaction force profile for each trial at 30-, 60-, and 90-cm platform heights. A 2 x 3 (group x height) mixed-factors analysis of variance was calculated for each of the 6 variables. RESULTS: The group-by-height interaction was significant for F1, F2, and impulse to F2. Tukey post hoc analyses revealed significantly higher values for the gymnasts than for the recreational athletes at 60- and 90-cm heights for F1 and F2 magnitudes. Differences between groups for T1, T2, impulse to F1, and impulse to F2 were not statistically significant at any height. CONCLUSIONS: Drop landings performed by female gymnasts at 60- and 90-cm heights exhibited higher vertical ground reaction forces than drop landings performed by female recreational athletes. High ground reaction forces experienced by gymnasts during landings may contribute to the incidence of lower extremity injuries.
In the standard inverse dynamic method, joint moments are assessed from ground reaction force data and position data, where segmental accelerations are calculated by numerical differentiation of position data after low-pass filtering. This method falls short in analyzing the impact phase, e.g. landing after a jump, by underestimating the contribution of the segmental accelerations to the joint moment assessment. This study tried to improve the inverse dynamics method for the assessment of knee moment by evaluating different cutoff frequencies in low-pass filtering of position data on the calculation of knee moment. Next to this, the effect of an inclusion of direct measurement of segmental acceleration using accelerometers to the inverse dynamics was evaluated. Evidence was obtained that during impact, the contribution of the ground reaction force to the sagittal knee moment was neutralized by the moments generated by very high segmental accelerations. Because the accelerometer-based method did not result in the expected improvement of the knee moment assessment during activities with high impacts, it is proposed to filter the ground reaction force with the same cutoff frequency as the calculated accelerations. When this precaution is not taken, the impact peaks in the moments can be considered as artifacts. On the basis of these findings, we recommend in the search to biomechanical explanations of chronic overuse injuries, like jumper's knee, not to consider the relation with impact peak force and impact peak moment.
Neuromuscular training that includes both plyometric and dynamic stabilization/balance exercises alters movement biomechanics and reduces ACL injury risk in female athletes. The biomechanical effects of plyometric and balance training utilized separately are unknown.
A protocol that includes balance training without plyometric training will decrease coronal plane hip, knee, and ankle motions during landing, and plyometric training will not affect coronal plane measures. The corollary hypothesis was that plyometric and balance training effects on knee flexion are dependent on the movement task tested.
Controlled laboratory study.
Eighteen high school female athletes participated in 18 training sessions during a 7-week period. The plyometric group (n = 8) performed maximum-effort jumping and cutting exercises, and the balance group (n = 10) used dynamic stabilization/ balance exercises during training. Lower extremity kinematics were measured during the drop vertical jump and the medial drop landing before and after training using 3D motion analysis techniques.
During the drop vertical jump, both plyometric and balance training reduced initial contact (P = .002), maximum hip adduction angle (P = .015), and maximum ankle eversion angle (P = .020). During the medial drop landing, both groups decreased initial contact (P = .002) and maximum knee abduction angle (P = .038). Plyometric training increased initial contact knee flexion (P = .047) and maximum knee flexion (P = .031) during the drop vertical jump, whereas the balance training increased maximum knee flexion (P = .005) during the medial drop landing.
Both plyometric and balance training can reduce lower extremity valgus measures. Plyometric training affects sagittal plane kinematics primarily during a drop vertical jump, whereas balance training affects sagittal plane kinematics during single-legged drop landing.
Both plyometric and dynamic stabilization/balance exercises should be included in injury-prevention protocols.
In this paper, the hypothesis that multijoint control strategies are transferred between similar tasks was tested. To test this hypothesis, we studied the take-off phase of two types of backward somersault dives: one while translating backwards (Back), the other while translating forward (Reverse). An experimentally based dynamic model of the musculoskeletal system was employed to simulate the measured kinematics and reaction force data and to study the sensitivity of take-off performance to initial kinematic conditions. It was found that the horizontal velocity of the total body center of mass (CM) was most sensitive to modifications in the initial shank conditions. Consequently, the initial shank kinematics of the Back dive was modified in the optimization procedure while maintaining the joint coordination of the Back in order to generate the CM trajectory and reaction forces of a Reverse. Similarly, the initial shank kinematics of the Reverse dive was modified to simulate the CM trajectory and reaction force of the Back. It was found that small modifications in the initial shank kinematics led to change in direction of horizontal CM velocity at take-off; resulting in a switch from Back to Reverse and vice versa. In both cases, the simulated momentum conditions at departure and the bimodal shape of the reaction force-time curve were consistent with those experimentally observed. The results of this study support the hypothesis that transfer of control strategies between similar tasks is a viable option in multijoint control. This transfer of control strategy is explained using a hierarchical model of the motion control system.
To determine if ankle muscular strength, flexibility and proprioception can predict ankle injury in college basketball players and to compare ankle injury rates in female and male players.
In this prospective, correlational study, subjects were tested at the start of the competitive season for ankle joint muscle strength, flexibility, and proprioception. The first ankle injury for each subject was recorded on an injury report form, and the data were analyzed to determine if any of these preseason measurements predicted future injury. The setting was a competitive 9-week season for four women's and four men's college basketball teams.
A convenience sample of 31 female and 11 male college basketball players.
Subjects were tested for ankle dorsiflexion range of motion, various measures of ankle proprioception, and isokinetic peak torque of ankle dorsiflexion-plantar flexion and eversion-inversion at 30 degrees /sec and 180 degrees /sec before the start of the conference basketball seasons. Data were analyzed using a series of multiple regression equations to determine the variance in ankle injury attributed to each variable.
Various measures of proprioception predicted left ankle injury in all subjects (p < .05), while ankle strength and flexibility measures failed to account for additional variance. There was no statistically significant difference in ankle injury rate between women and men.
Ankle joint proprioceptive deficits can be used to predict ankle injury, but further research is needed to identify other sources of variance. In our study, ankle injury rate was similar in female and male college basketball players.
Female athletes land from a jump with greater knee valgus and ankle pronation/eversion. Excessive valgus and pronation have been linked to risk of anterior cruciate ligament injury. A medially posted orthosis decreases component motions of knee valgus such as foot pronation/eversion and tibial internal rotation.
We hypothesized a medial post would decrease knee valgus and ankle pronation/eversion during drop-jump landings in NCAA-I female athletes.
Controlled laboratory study.
Knee and ankle 3-dimensional kinematics were measured using high-speed motion capture in 10 National Collegiate Athletic Association Division I female athletes during a drop-jump landing with and without a medial post. Analysis of variance was used to determine differences in posting condition, t tests were used to determine dominant-nondominant differences, and the Pearson correlation coefficient was used to determine relationships between variables.
Significant differences were found for all measures in the posted condition. A medial post decreased knee valgus at initial contact (1.24 degrees , P < .01) and maximum angle (1.21 degrees , P < .01). The post also decreased ankle pronation/eversion at initial contact (0.77 degrees , P < .01) and maximum angle (0.95 degrees , P = .039).
The authors have demonstrated a significant decrease in knee valgus and ankle pronation/eversion during a drop jump with a medial post placed in the athletes' shoes.
A medial post may be a potential means to decrease risk of anterior cruciate ligament injury.
Lack of the necessary magnitude of energy dissipation by lower extremity joint muscles may be implicated in elevated impact stresses present during landing from greater heights. These increased stresses are experienced by supporting tissues like cartilage, ligaments and bones, thus aggravating injury risk. This study sought to investigate frontal plane kinematics, kinetics and energetics of lower extremity joints during landing from different heights. Eighteen male recreational athletes were instructed to perform drop-landing tasks from 0.3- to 0.6-m heights. Force plates and motion-capture system were used to capture ground reaction force and kinematics data, respectively. Joint moment was calculated using inverse dynamics. Joint power was computed as a product of joint moment and angular velocity. Work was defined as joint power integrated over time. Hip and knee joints delivered significantly greater joint power and eccentric work (p<0.05) than the ankle joint at both landing heights. Substantial increase (p<0.05) in eccentric work was noted at the hip joint in response to increasing landing height. Knee and hip joints acted as key contributors to total energy dissipation in the frontal plane with increase in peak ground reaction force (GRF). The hip joint was the top contributor to energy absorption, which indicated a hip-dominant strategy in the frontal plane in response to peak GRF during landing. Future studies should investigate joint motions that can maximize energy dissipation or reduce the need for energy dissipation in the frontal plane at the various joints, and to evaluate their effects on the attenuation of lower extremity injury risk during landing.
Ground reaction forces (GRF), joint positions, joint moments, and muscle powers in the lower extremity were compared between soft and stiff landings from a vertical fall of 59 cm. Soft and stiff landings had less than and greater than 90 degrees of knee flexion after floor contact. Ten trials of sagittal plane film and GRF data, sampled at 100 and 1000 Hz, were obtained from each of eight female athletes and two landing conditions. Inverse dynamics were performed on these data to obtain the moments and powers during descent (free fall) and floor contact phases. Angular impulse and work values were calculated from these curves, and the conditions were compared with a correlated t-test. Soft and stiff landings averaged 117 and 77 degrees of knee flexion. Larger hip extensor (0.010 vs 0.019 N.m.s.kg-1; P less than 0.01) and knee flexor (-0.010 vs -0.013 N.m.s.kg-1; P less than 0.01) moments were observed during descent in the stiff landing, which produced a more erect body posture and a flexed knee position at impact. The shapes of the GRF, moment, and power curves were identical between landings. The stiff landing had larger GRFs, but only the ankle plantarflexors produced a larger moment (0.185 vs 0.232 N.m.s.kg-1; P less than 0.01) in this condition. The hip and knee muscles absorbed more energy in the soft landing (hip, -0.60 vs -0.39 W.kg-1; P less than 0.01; knee, -0.89 vs -0.61 W.kg-1; P less than 0.01), while the ankle muscles absorbed more in the stiff landing (-0.88 vs -1.00 W.kg-1; P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
In this study, the landing preferences of gymnasts (n = 6) and recreational athletes (n = 6) were determined by comparing the changes in lower extremity kinetics of drop landings performed from three heights (0.32-1.28 m). Net joint moments and work done on the extensor muscles of the ankle, knee, and hip were selected as variables representative of the demand placed on the muscles responsible for controlling flexion and dissipating the load. Kinematic and kinetic two-dimensional data were acquired simultaneously using high-speed film (202.4 fps) and a force plate (1000 Hz). Reaction forces and lower extremity joint motions were used to calculate net joint forces, net joint moments powers, and work done on the extensor muscles of the ankle, knee, and hip. Results indicated that the extensor joint moments tended to peak earlier after contact with increases in velocity, but the temporal sequence of events was maintained independently of velocity or group. As impact velocity increased, net peak extensor moments and work done on the extensor muscles significantly increased. Significantly larger ankle and hip peak extensor moments were observed for the gymnasts across velocities as compared to the recreational athletes. No significant differences in work done on the extensor muscles were noted between groups. Significant interaction effects indicate that gymnasts chose to dissipate the loads at contact by using larger ankle and hip extensor moments at higher impact velocities than the recreational athletes, whereas recreational athletes chose to adjust their strategy by using greater degrees of hip flexion (McNitt-Gray, Int. J. Sport Biomech, 7, 201-204, 1991) and longer landing phase durations than the gymnasts. The greater demands placed on the ankle and hip extensors by the gymnasts, as compared to the recreational athletes, may be explained by the need to maintain balance during competitive gymnastics landings or, perhaps, by the inability of recreational athletes to produce larger extensor moments at the ankle or hip during landings from great heights.
In this prospective study, the parachuting injuries which occurred during 2031 jumps in basic courses of free fall were compared with the injuries occurring during 2468 jumps for reserve paratroopers on training exercises. Fifty-eight injuries were recorded in 51 paratroopers. The ankle was most commonly affected, and 80 per cent of the injuries involved the lower extremity. Only 14 per cent of the injured troopers suffered severe injuries (fractures, knee ligament ruptures). The injury rate for paratroopers on basic courses (19.7 injuries per 1000 jumps) was significantly higher (P < 0.0001) than for those on training exercises (4.5 injuries per 1000 jumps). Similar observations were made for severe injuries (2.0 versus 1.2 injuries per 1000 jumps, respectively). The injury risk increased with age. Most of the injuries occurred on landing, and about 70 per cent were mainly caused by improper landing fall technique. The rate of serious parachuting injuries was low for Norwegian paratroopers.
The control of self-initiated falls from different heights was studied. The objective of the study was to investigate in a quantitative manner the modulation of EMG timing (i.e. onset from take-off and duration from onset to touch-down) and amplitude (before and after foot contact) as a function of fall height. The muscles studied were m. soleus and m. tibialis anterior. Kinematic (ankle joint angle) and kinetic (ground reaction force) variables were also measured. Six subjects took part in the experiments that consisted of ten landings from each of five heights (0.2, 0.4, 0.6, 0.8 and 1 m) onto a force platform. We found a consistent pattern of co-contraction before and after touch-down across the fall heights studied. In both muscles, the onset of pre-landing EMG activity occurred at a longer latency following take-off when landing from greater heights. The absolute EMG duration was affected to a lesser extent by increasing fall height. These findings suggest that the onset of muscle activity of the muscles studied prior to foot contact is timed relative to the expected time of foot contact. Pre- and post-landing EMG amplitude tended to increase with height. Despite a doubling in the magnitude of ground reaction force, the amplitude of ankle joint rotation caused by the impact remained constant across heights. These findings suggest that the observed pattern of co-contraction is responsible for increasing ankle joint stiffness as fall height is increased. The attainment of an appropriate level of EMG amplitude seems to be controlled by (a) timing muscle activation at a latency timed from the expected instant of foot contact and (b) varying the rate at which EMG builds up.
The purpose of this prospective study was to determine whether an association exists between foot structure and the development of musculoskeletal overuse injuries. The study group was a well-defined cohort of 449 trainees at the Naval Special Warfare Training Center in Coronado, California. Before beginning training, measurements were made of ankle motion, subtalar motion, and the static (standing) and dynamic (walking) characteristics of the foot arch. The subjects were tracked prospectively for injuries throughout training. We identified risk factors that predispose people to lower extremity overuse injuries. These risk factors include dynamic pes planus, pes cavus, restricted ankle dorsiflexion, and increased hindfoot inversion, all of which are subject to intervention and possible correction.
The purpose of the study was to investigate changes in lower extremity joint energy absorption for different landing heights and landing techniques.
Nine healthy, active male subjects volunteered to perform step-off landings from three different heights (0.32 m, 2.5 m(-s); 0.62 m, 3.5 m(-s); and 1.03 m, 4.5 m(-s)) using three different landing techniques (soft, SFL; normal, NML; and stiff landing, STL). Each subject initially performed five NML trials at 0.62 m to serve as a baseline condition and subsequently executed five trials in each of the nine test conditions (3 heights x 3 techniques).
The results demonstrated general increases in peak ground reaction forces, peak joint moments, and powers with increases in landing height and stiffness. The mean eccentric work was 0.52, 0.74, and 0.87 J x kg(-1) by the ankle muscles, and 0.94, 1.31, and 2.15 J x kg(-1) by the hip extensors, at 0.32, 0.62, and 1.03 m, respectively. The average eccentric work performed by the knee extensors was 1.21, 1.63, and 2.26 J x kg(-1) for the same three heights.
The knee joint extensors were consistent contributors to energy dissipation. The ankle plantarflexors contributed more in the STL landings, whereas the hip extensors were greater contributors during the SFL landings. Also a shift from ankle to hip strategy was observed as landing height increased.
OBJECTIVE: To ascertain the possibility of non-uniform stress within the achilles tendon due to individual force contributions of the triceps surae. DESIGN: Calculation of non-uniform stress through discrepancies in moments about the ankle joint. BACKGROUND: Non-uniform stress over the cross-sectional area have been implied in the etiology of achilles tendon injury and may influence functional aspects. However, this has not been empirically demonstrated. METHODS: In vivo achilles tendon forces were measured with an optic fibre technique during isometric plantarflexions at systematically varied knee angles and contraction intensities. A comparison to the plantar force measured underneath the metatarsal heads permitted the calculation of the achilles tendon contribution to the resultant plantarflexion moment. The achilles tendon force was further differentiated into gastrocnemius and soleus contributions. Individual muscle activation patterns were described. RESULTS: The average achilles tendon contribution to the resultant moment was 67.4%. Variations were found at different knee angles and contraction intensities. A force discrepancy of 967 N occurred between gastrocnemius and soleus over a gastrocnemius length change of 2.67 cm. This corresponded to a stress discrepancy of 21 N/mm(2) over the tendon cross-sectional area. Separate muscles showed individual activation patterns. CONCLUSIONS: Non-uniform stress in the achilles tendon can occur through modifications of individual muscle contributions. RELEVANCE: Non-uniform stress in the achilles tendon has been implied in its injury etiology. This study demonstrated such loading resulting from discrepancies in individual muscle forces.
An understanding of landing techniques is important for the prevention of injuries in a number of athletic events. There is a risk of injury to the ankle during landings, and the kinematics and forces involved in different landing strategies may be related to the occurrence of trauma.
In the current study, four drop conditions from a 30.48-cm (12-inch) height were tested. The conditions were a) BN: Bent knee (self-selected), Natural (self-selected) plantar flexor contraction; b) SN: Stiff-knee, Natural plantar flexors; c) SP: Stiff-knee, Plantar flexors absorbing the impact; and d) SH: Stiff-knee, absorbing most of the impact in the Heels. Peak vertical forces and accelerations were measured, and Achilles tendon forces and stiffnesses were calculated.
Peak vertical forces and peak tibial accelerations were highest for the SH condition (2418 N and 20.7 G), whereas peak Achilles tendon force was highest for SP drops. The overall average AT stiffness was 166,345 N x m(-1).
The results from the study were used in an extensive cadaver study to investigate ankle injuries. The data from the current study indicate that athletes may not use their full energy absorbing potential in landings during sporting activities.
This study aimed to evaluate the inter-rater and intra-rater reliability of a weight-bearing dorsiflexion (DF) lunge in 13 healthy subjects. Our raters with varying clinical experience tested all subjects in random order. Two of the raters repeated the measurements one week later. Two methods were used to assess the DF lunge: (i) the distance from the great toe to the wall and (ii) the angle between the tibial shaft and the vertical using an inclinometer. The average of three trials was used in data analysis. Intra-rater intraclass correlation coefficients (iccs) ranged from 0.97 to 0.98. Inter-rater ICC values were 0.97 (angle) and 0.99 (distance). results indicate excellent reliability for both methods of assessing a DF lunge.
This study investigated effects of ankle dorsiflexion range and pre-exercise calf muscle stretching on relative risk of selected injuries in 1093 male Army recruits undertaking 12 weeks of intensive training. Prior to training, ankle dorsiflexion range was measured and recruits were allocated to stretch and control groups using a quasi-random procedure. The stretch group stretched calf muscles under supervision prior to all intense exercise. The control group stretched upper limb muscles instead. Forty-eight injuries were recorded. Survival analysis indicated that ankle dorsiflexion range was a strong predictor of injury (p = 0.03). Definitive evidence of an effect of stretching on injury risk was not found (p = 0.76), but the sample size may have been insufficient to detect such an effect.
Different tendons are (i) subject to very different stresses from their muscles and (ii) differ in their susceptibility to fatigue damage. The fatigue quality of each tendon is matched to the stress it experiences, so that, in life, all tendons are similarly prone to damage. On-going damage must be routinely repaired to maintain homeostasis and prevent damage from becoming symptomatic. The discovery of major differences in fatigue quality among tendons, which had previously seemed fairly similar in their mechanical properties, raises a wide range of new questions. (A) What structural and chemical differences underlie the variations in fatigue quality? (B) What molecular structure in the tendon is damaged and how is repair organised? (C) Is fatigue quality adaptable and if so what is the trigger for adaptation? Putting these questions into context leads to an integrated review of tendon, including structure and chemistry, the turnover of proteins, the cross-linking of collagen and the response of tenocytes to load on the tendon.
Lower extremity stiffness is thought to be an important factor in musculoskeletal performance. However, too little or too much stiffness is believed to increase the risk of musculoskeletal injury.
To provide a current update of the lower extremity stiffness literature as it pertains to both performance and injury.
It appears that increased stiffness is beneficial to performance. As well it appears that there may be an optimal amount of stiffness that allows for injury-free performance. There is some evidence that increased stiffness may be related to bony injuries and decreased stiffness may be associated with soft tissue injuries. Further investigations should evaluate the relationship between stiffness and injury prospectively. Initial reports suggest that stiffness can be modified in response to the external environment or verbal cues.
A greater understanding of the role of stiffness in both performance and injury will provide a stronger foundation for the development of optimal training intervention programs.
The aims of this study were: (a) to examine the effect of falling height on the kinematics of the tibiotalar, talonavicular and calcaneocuboid joints and (b) to study the influence of falling height on the muscle activity of the leg during landings. Six female gymnasts (height: 1.63 +/- 0.04 m, weight: 58.21 +/- 3.46 kg) participated in this study. All six gymnasts carried out barefoot landings, falling from 1.0, 1.5 and 2.0 m height onto a mat. Three genlocked digital high speed video cameras (250 Hz) captured the motion of the left shank and foot. Surface electromyography (EMG) was used to measure muscle activity (1000 Hz) from five muscles (gastrocnemius medialis, tibialis anterior, peroneus longus, vastus lateralis and hamstrings) of the left leg. The kinematics of the tibiotalar, talonavicular and calcaneocuboid joints were studied. The lower-leg and the foot were modelled by means of a multi-body system, comprising seven rigid bodies. The falling height does not show any influence on the kinematics neither of the tibiotalar nor of the talonavicular joints during landing. The eversion at the calcaneocuboid joint increases with increasing falling height. When augmenting falling height, the myoelectric activity of the muscles of the lower limb increases as well during the pre-activation phase as during the landing itself. The muscles of the lower extremities are capable of stabilizing the tibiotalar and the talonavicular joints actively, restricting their maximal motion by means of a higher activation before and after touchdown. Maximal eversion at the calcaneocuboid joint increases about 52% when landing from 2.0 m.
The effect of widely differing but normal passive ankle flexibility on function was investigated by using able-bodied males selected from the upper and lower tails of a group normally distributed for passive dorsiflexion (DF) flexibility. Ankle, knee and hip kinematics, and kinetics were quantified during stair descent, walking and standing up. The effect of DF flexibility was apparent during stair descent, but not in standing up or walking. Mean peak DF in stance phase of stair descent was 11.5 degrees lower for 'inflexible' compared with 'flexible' subjects, but the net moment about the ankle at peak DF and the timing of peak DF were comparable between groups.
Despite recent evidence supporting the use of neuromuscular training to reduce anterior cruciate ligament injury risk, female athletes continue to show an increased anterior cruciate ligament injury rate in collegiate basketball and soccer when compared to males. The purpose of the current study was to identify gender and task differences in measures that may increase the risk of anterior cruciate ligament injury in female basketball and soccer athletes.
Eleven female and 11 male collegiate basketball and soccer athletes were height (female mean 176 (SD 8 cm), male mean 176 (SD 8 cm)) and weight (female mean 73 (SD 7 kg), male mean 74 (SD 6 kg)) matched. Three-dimensional motion analysis was used to calculate differences in total coronal plane angular joint excursion (maximum-minimum) between male and female athletes when performing a series of medially and laterally directed drop landings.
Female athletes demonstrated increased total coronal plane excursion for the hip, knee and ankle (P < 0.05) during the medial drop landing. During the lateral drop landing females displayed increased excursion at the hip and knee. When comparing tasks, the lateral drop landing resulted in greater coronal plane excursion at the hip (P < 0.05) while the knee showed no differences between movements. In contrast, females demonstrated increased ankle excursion during the medial drop task (P < 0.05).
Female athletes demonstrate increased lower extremity coronal plane excursion when performing single leg drop landing in both the medial and lateral direction when compared to height/weight matched male athletes. This increased coronal plane oscillation of lower extremity joints may be related to the increased risk of anterior cruciate ligament injury for female basketball and soccer athletes.
The present study examined the effect of continuous vision and its occlusion in timing of pre-landing actions during free falls. When vision is occluded, muscle activation is hypothesized to start relative to onset of the fall. However, when continuous vision is available onset of action is hypothesized to be relative to the moment of touchdown. Six subjects performed 6 randomized sets of 6 trials after becoming familiar with the task. The 36 trials were divided in 2 visual conditions (vision and blindfold) and 3 heights of fall (15, 45 and 75 cm). EMG activity was recorded from the gastrocnemius and rectus femoris muscles during the falls. The latency of onset (L(o)) and the lapse from EMG onset to touchdown (T(c)) were obtained from these muscles. Vertical forces were recorded to assess the effects of pre-landing activity on the impacts at collision with and without continuous vision. Peak amplitude (F(max)), time to peak (T(max)) and peak impulse normalized to momentum (I(norm)) were used as outcome measures. Within flight time ranges of approximately 50-400 ms, the results showed that L(o) and T(c) follow a similar linear trend whether continuous vision was available or occluded. However, the variability of T(c) for each of the muscles was larger in the vision occluded condition. Analyses of variance showed that the rectus femoris muscle started consistently earlier in no vision trials. Finally, impact forces were not different in vision or blindfold conditions, and thus, they were not affected by minor differences in the timing of muscles prior to landing. Thus, it appears that knowing the surroundings before falling may help to reduce the need for a continuous visual input. The relevance of such input cannot be ruled out for falls from high landing heights, but cognitive factors (e.g., attention to specific cues and anticipation of a fall) may play a dominant role in timing actions during short duration falls encountered daily.
Patellar tendon injury, a chronic overuse injury characterised by pain during tendon loading, is common in volleyball players and may profoundly restrict their ability to compete. This cross-sectional study investigated the association between performance factors and the presence of patellar tendon injury. These performance factors (sit and reach flexibility, ankle dorsiflexion range, jump height, ankle plantarflexor strength, years of volleyball competition and activity level) were measured in 113 male and female volleyball players. Patellar tendon health was determined by measures of pain and ultrasound imaging. The association between these performance factors and patellar tendon health (normal tendon, abnormal imaging without pain, abnormal imaging with pain) was investigated using analysis of variance. Only reduced ankle dorsiflexion range was associated with patellar tendinopathy (p<0.05). As coupling between ankle dorsiflexion and eccentric contraction of the calf muscle is important in absorbing lower limb force when landing from a jump, reduced ankle dorsiflexion range may increase the risk of patellar tendinopathy.
The likelihood of sustaining an ACL injury in a noncontact situation is two to eight times greater for females than for males. However, the mechanism and risk factors of ACL injury are still unknown. We compared knee kinematics as well as electromyographic activity during landing between male and female athletes. Eighteen male athletes and nineteen female athletes participated in the experiment. The angular displacements of flexion/extension, valgus/varus, and internal/external tibial rotation, as well as the translational displacements of anterior/posterior tibial translation during single limb drop landing were calculated. Simultaneous electromyographical activity of the rectus femoris (RF) and hamstrings (Ham) was taken. During landing, internal tibial rotation of the females was significantly larger than that of the males, while differences were not observed in flexion, varus, valgus, and anterior tibial translation. Hamstrings/quadriceps ratio (HQR) for the 50 ms time period before foot contact was greater in males than in females. The mechanism of noncontact ACL injury during a single limb drop landing would be internal tibial rotation combined with valgus rotation of the knee. Increased internal tibial rotation combined with greater quadriceps activity and a low HQR could be one reason female athletes have a higher incidence of noncontact ACL injuries.
Females have an increased incident rate of anterior cruciate ligament tears compared to males. Biomechanical strategies to decelerate the body in the vertical direction have been implicated as a contributing cause. This study determined if females would exhibit single leg landing strategies characterized by decreased amounts of hip, knee, and ankle flexion resulting in greater vertical ground reaction forces and altered energy absorption patterns when compared to males.
Recreationally active males (N=14) and females (N=14), completed five single leg landings from a 0.3m height onto a force platform while three-dimensional kinematics and kinetics were simultaneously collected.
Compared to males, females exhibited (1) less total hip and knee flexion displacements (40% and 64% of males, respectively, P<0.05) and less time to peak hip and knee flexion (48% and 78% of males, respectively, P<0.05), (2) 9% greater peak vertical ground reaction forces (P<0.05), (3) less total lower body energy absorption (76% of males, P<0.05), and (4) 11% greater relative energy absorption at the ankle (P<0.05).
Females in this study appear to adopt a single leg landing style using less hip and knee flexion, absorbing less total lower body energy with more relative energy at the ankle resulting in a landing style that can be described as stiff. This may potentially cause increased demands on non-contractile components of the lower extremity. Preventative training programs designed to prevent knee injury may benefit from the biomechanical description of sex-specific landing methods demonstrated by females in this study by focusing on the promotion of more reliance on using the contractile components to absorb impact energy during landings.
To review 16 years of National Collegiate Athletic Association (NCAA) injury surveillance data for women's gymnastics and identify potential areas for injury prevention initiatives.
In the 1988-1989 academic year, 112 schools were sponsoring varsity women's gymnastics teams, with approximately 1550 participants. By 2003-2004, the number of varsity teams had decreased 23% to 86, involving 1380 participants. Significant participation reductions during this time were particularly apparent in Divisions II and III.
A significant annual average decrease was noted in competition (-4.0%, P < .01) but not in practice (-1.0%, P = .35) injury rates during the sample period. Over the 16 years, the rate of injury in competition was more than 2 times higher than in practice (15.19 versus 6.07 injuries per 1000 athlete-exposures; rate ratio = 2.5, 95% confidence interval [CI] = 2.3, 2.8). A total of 53% of all competition and 69% of all practice injuries were to the lower extremity. A participant was almost 6 times more likely to sustain a knee internal derangement injury in competition than in practice (rate ratio = 5.7, 95% CI = 4.5, 7.3) and almost 3 times more likely to sustain an ankle ligament sprain (rate ratio = 2.7, 95% CI = 2.1, 3.4). The majority of competition injuries (approximately 70%) resulted from either landings in floor exercises or dismounts.
Gymnasts with a previous history of ankle sprain should either wear an ankle brace or use prophylactic tape on their ankles to decrease the risk of recurrent injury. Preventive efforts may incorporate more neuromuscular training and core stability programs in the off-season and preseason conditioning to enhance proper landing and skill mechanics. Equipment manufacturers are encouraged to reevaluate the design of the landing mats to allow for better absorption of forces.
Although parachute landing injuries are thought to be due in part to a lack of exposure of trainees to realistic descent velocities during parachute landing fall (PLF) training, no research has systematically investigated whether PLF technique is affected by different vertical descent conditions, with standardized and realistic conditions of horizontal drift. This study was designed to determine the effects of variations in vertical descent velocity on PLF technique.
Kinematic, ground reaction force, and electromyographic data were collected and analyzed for 20 paratroopers while they performed parachute landings, using a custom-designed monorail apparatus, with a constant horizontal drift velocity (2.3 m x s(-1)) and at three realistic vertical descent velocities: slow (2.1 m x s(-1)), medium (3.3 m x s(-1)), and fast (4.6 m x s(-1)).
Most biomechanical variables characterizing PLF technique were significantly affected by descent velocity. For example, at the fast velocity, the subjects impacted the ground with 123 degrees of plantar flexion and generated ground reaction forces averaging 13.7 times body weight, compared to 106 degrees and 6.1 body weight, respectively, at the slow velocity. Furthermore, the subjects activated their antigravity extensor muscles earlier during the fast velocity condition to eccentrically control the impact absorption.
As vertical descent rates increased, the paratroopers displayed a significantly different strategy when performing the PLF. It is therefore recommended that PLF training programs include ground training activities with realistic vertical descent velocities to better prepare trainees to withstand the impact forces associated with initial aerial descents onto the Drop Zone and, ultimately, minimize the potential for injury.
ACSM's Guidelines for Exercise Testing and Prescription
- B Franklin
- M Whaley
- E Howley
Franklin B, Whaley M, Howley E. ACSM's Guidelines for Exercise
Testing and Prescription. 6th ed. Philadelphia (PA): Lippincott
Williams & Wilkins; 2000. p. 23.
Introduction to Surface Electromy-ography
- Cram Jr
- Gs Kasman
- Holtz
Cram JR, Kasman GS, Holtz J. Introduction to Surface Electromy-ography. Gaithersburg (MD): Aspen Publications; 1998. p. 360–75.
Biomechanics of the Musculo-skeletal Sys-tem
- Nigg Bm
- Herzog
Nigg BM, Herzog W. Biomechanics of the Musculo-skeletal Sys-tem. 3rd ed. Chichester (UK): John Wiley & Sons; 2007. p. 418.
Science in Sports & Exercise d 713 APPLIED SCIENCES Copyright © 2011 by the American College of Sports Medicine Unauthorized reproduction of this article is prohibited
- Dorsiflexion Range And Landing Mechanics
- Medicine
DORSIFLEXION RANGE AND LANDING MECHANICS Medicine & Science in Sports & Exercise d 713 APPLIED SCIENCES Copyright © 2011 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.
- R Merletti
- Standards
- Emg Reporting
- Data
Merletti R. Standards for Reporting EMG data. J Electromyogr
Kinesiol. 1999;9(1):III–IV.
Biomechanics of the Musculo-skeletal System
- B M Nigg
- W Herzog
Nigg BM, Herzog W. Biomechanics of the Musculo-skeletal System. 3rd ed. Chichester (UK): John Wiley & Sons; 2007. p. 418.
Ankle joint dorsiflexion: assessment of true values
- J Weir
- N Chokalingam
Weir J, Chokalingam N. Ankle joint dorsiflexion: assessment of
true values. Int J Ther Rehabil. 2007;14(2):76-82.