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-Examples of vertical jump modalities. (a) SJ: squat jump; (b) CMJ: counter-movement jump; (c) RJ: rebound-continuous jump; (d) AJ: rebound-continuous ankle jump.
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This study aimed to determine the demand of strengthpower capabilities represented by traditional and anklespecific vertical jump modalities-squat jump (SJ), countermovement jump (CMJ), reboundcontinuous jump (RJ), reboundcontinuous ankle jump (AJ)-relative to sprint acceleration ability during the entire acceleration phase of maximal sprint.
Ninet...
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Context 1
... performing the sprint test and resting for 30 minutes for full recovery, participants performed vertical jump tests in the order of SJ, CMJ, RJ, and rebound-continuous ankle jump (AJ) with resting for 3 minutes between each jump modality ( Figure 1). These jump tests were used as usual training in the above-mentioned order (non-randomized) by all participants, and each jump test was not an ex- hausting exercise. Thus, the influence of fatigue was negligible. All jumps were performed without arm- sessions, thereby improving the quality of training programs according to the specific need for strength ...
Context 2
... means and standard deviations were calculat- ed. Pearson's correlation test was used to analyse the relationship between two variables and the relation- ships between acceleration and jump performances at every step. The significance level was set at 5% for all tests. Table I For the RJ, the participants were instructed to jump as high as possible and push against the ground as quickly as possible. The jump with the highest in- dex (explained below), excluding the first and last jumps, was chosen for statistical analysis. The AJ was performed only with plantar flexion, without any other joint movement with reference to previous studies, 31, 32 although we used continuous jumps. To perform the AJ, the participants stood with their legs straight and began jumping with only plantar flexion. Before touching the ground, the participants tried to keep their bodies straight without flexing their knees or hips, and attempted to push off the ground with only ankle and metatarsophalangeal (MTP) plantar flexion. The AJ comprised six jumps, and the jump with the highest index, excluding the first and last jumps, was chosen for statistical analysis. For the AJ, the participants were instructed to jump as high as possible, to keep their lower limbs fully straight, and to push against the ground as quickly as possible with RJ height were significant. The RJ index corre- lated with both RJ contact time (r=−0.56) and height (r=0.88). The correlation of the AJ index with AJ height was significant (r=0.97). There was a signifi- cant positive correlation between RJ and AJ contact times (r=0.52). Figure 2 shows the means and standard devia- tions of running speed and acceleration. Running speed reached maximal speed (9.52±0.41 ms −1 ) at the 24th step. Figure 3 shows the correlation coef- as the distance increased, and it was pointed out that the SJ and CMJ are more predictive of performance during the early stage of the 100-m sprint. However, in those studies, significant correlations were actu- ally found between the SJ and CMJ and the mean running speed from the start to 10 m, 10 to 30 m, and 30 to 60 m. In contrast, we used step-to-step accel- eration to assess the sprint performance, and found significant correlations only during the earlier stage of acceleration. Accordingly, the use of step-to-step acceleration to assess sprint acceleration perform- ance appropriately at the spot is more advantageous than the use of running speed. During the early stage of acceleration, the support time is longer than that during the later stage, and the posture at the time of foot-strike is characterized by a deeply flexed hip and knee and a forward-leaning trunk. 33 Likewise, the durations of force production in the SJ and CMJ are longer than those for the RJ or AJ, 22 and the lowest positions in the SJ and CMJ involve a deeply flexed hip and knee and forward- leaning trunk (Figure 1). Moreover, both sprinting during the early stage of acceleration and the SJ and CMJ are accomplished with explosive extension and plantar flexion of the three major lower extremity joints. 7,22 Therefore, these similarities in joint be- haviour and characteristics of force production are probably responsible for the relationship between sprint acceleration ability during the earlier stage and SJ and CMJ ...
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... For each explosive task, these variables included (a) the impulse (integral over time) of the vertical (Fz) and/or horizontal (Fy) and/or medio-lateral GRF (Fx); (b) the effective impulse of the vertical GRF i.e., the product of the stance phase duration by the average vertical GRF applied above body-weight; (c) the net impulse of the horizontal GRF and the impulse of each component of the horizontal GRF, i.e., the negative (braking) and positive (propulsive) components; (d) the ratio of forces (RF), i. e the ratio of the step-or phase averaged Fy or Fx component divided by the resultant of the step-or phase averaged GRF (FTot); and (e) the contact time defined by the events of footstrike and toe-off from the raw GRF data (Fz threshold of 20 N for sprinting and 10 N for cutting). Finally, participants performed a jumping task called "Foot-Ankle Rebound Jumps" (FARJ), which was used to evaluate foot-ankle reactive strength and stretch-shortening cycle (SSC) capacities (Bosco et al., 1982;Nagahara et al., 2014). Participants were instructed to jump "as high as possible" while keeping their lower limbs fully straight, and to push against the ground "as quickly as possible" with only a plantarflexion of the ankle and the MTPj during eight jumps (Bosco et al., 1982). ...
... Participants were instructed to jump "as high as possible" while keeping their lower limbs fully straight, and to push against the ground "as quickly as possible" with only a plantarflexion of the ankle and the MTPj during eight jumps (Bosco et al., 1982). From the contact and flight time measured with an optoelectronic system (Optojump Next, Microgate, Bolzano, 113 Italy) the mean reactive strength index of four jumps (excluding the first and last two jumps of the series) was calculated as the ratio of jump height (using the flight time method) to contact time (Nagahara et al., 2014). ...
... These results hold significant implications, given that previous studies highlight the importance of a large vertical force production over a short contact time during the maximal speed phase for achieving a better sprint performance (Nagahara et al., 2018). The upright body posture adopted during maximal running speed likely increases the reliance on the ankle joint to transmit a large amount of force to the ground (Nagahara et al., 2014), as the ankle joint showed the greatest joint power compared to the knee and the hip joints during the support phase of maximal speed sprinting . However, it has also been shown that ankle plantarflexors (soleus and gastrocnemius) primarily influence net propulsive and vertical impulses throughout the entire acceleration phase (Pandy et al., 2021); our study revealed that relative MIPFt was not the predominant contributor in producing effective vertical impulse within a short duration at high speed. ...
... The reactive strength index (RSI) is the most common method for assessing the reactive strength of lower limbs [8]. The RSI is usually assessed as the ratio between jump height and contact time in specific jumps [9], such as drop jumps [10,11], rebound jumps [12] and hopping jumps (i.e., ankle jumps) [13,14]; thus, the RSI represents a commonly accepted measurement of the efficiency of the SSC [8]. Despite several studies investigating the relationship between RSIs and sprint performance in athletes of different disciplines [15], the association between RSIs and sprinting remains questionable [16]. ...
... Before performing the tests, athletes performed typical pre-competition 45 min warmups, including low-pace running, specific running exercises, active stretching and some sprints. After the warm-up, athletes performed the following assessments: a vertical drop jump (VDJ) and a horizontal drop jump (HDJ) from a 30 cm high box [16,27], a 20 m straightleg running drill (SLR) and a 60 m sprint [14]. Before data collection, the investigators gave verbal instructions about the tests' execution; all the athletes, however, were familiar with the tests. ...
... RSI RUN is determined by contact times and stride lengths in a sprint; these are parameters that have been indicated as crucial for sprint performance [5,29,30], and in particular for the maximum running speed [6]. Nagahara and colleagues [14] showed that the RS obtained by an ankle rebound test was more correlated with the 60 m sprint performance than the traditional RSI (r= −0.49 and r = −0.07, respectively), especially when this index was calculated in the advanced phases of athlete acceleration (from 23.4 ± 1.0 to 33.7 ± 1.4 m). ...
The aim of the present study was to assess a new reactive strength index (RSI RUN) based on contact time and stride length measured in sprint running and then to correlate this index with sprint performance, muscle architecture and echo intensity of the vastus lateralis. Participants included ten elite and sub-elite sprinters (age 24.4 ± 3.1 years, height 177.5 ± 7.7 cm, mass 69.8 ± 11.7 kg) who were tested with a vertical drop jump (VDJ) and a horizontal drop jump (HDJ) from a 30 cm high box, a 20 m straight-leg running drill (SLR) and a 60 m sprint. A nearly perfect correlation (r = from −0.90 to −0.96, p < 0.01) was detected between RSI RUN and sprint performance (30 m, 60 m and 100 m sprint time), and a very large correlation (r = from −0.72 to −0.77, p < 0.05) was found between the traditional RSI from vertical drop jump (RSIDJV) and sprint performance. In addition, the RSI RUN was more correlated to sprint performance than other RSI indices studied in previous research. The echo intensity of the vastus lateralis (VLEI) was largely correlated with maximum running speed (r = from 0.76 to 0.87, p < 0.05) and the RSI RUN (r = −0.80, p < 0.05). No significant correlations were noted between echo intensity and other RSIs. In conclusion, the RSI RUN and VLEI seem to be good predictors for track and field sprinting performance.
... ms (CMJ) (35). The RSI examines an athlete's ability to change quickly from an eccentric contraction to a concentric contraction and is calculated by dividing the JH by the CT and can be measured during DJ or the 10-5 RJT (30,45). Harper (18) noted that the 10-5 RJT can provide a quick and reliable means of monitoring individual progress and evaluating the success of interventions aimed at developing the reactive strength capabilities of their athletes, especially when working with a large group of athletes. ...
... Notably, as the velocity of the sprint and distance increase, there is a tendency for the relationships to increase in size throughout the phases. Nagahara et al. (30) also reported significant correlations with CMJ and acceleration from approximately 7 to 18 m from the start line. The CMJ and acceleration involves rapid extension and plantar flexion of the 3 major lowerextremity joints; therefore, these comparisons in joint movement could be responsible for the relationship between sprint acceleration ability and CMJ performance. ...
Brady, CJ, Harrison, AJ, Flanagan, EP, Haff, GG, and Comyns, TM. The relationship between the isometric squat and stretch shortening cycle function and sprint acceleration performance in hurling players. J Strength Cond Res XX(X): 000–000, 2024—The primary aim was to examine the relationship between sprint acceleration performance and the performance tests: isometric squat (ISqT), countermovement jump (CMJ), and reactive strength index (RSI). The secondary aim determined whether these tests could distinguish between sprint performance levels. Twenty-six male under-21 subjects completed the ISqT, with peak force (PF), relative PF, force at 100, 150, and 200 milliseconds (ms), and impulse (0–200 ms) measured. Jump height (JH) was calculated from the CMJ and RSI during the 10-5 repeated jump test. Subjects completed 3 × 30-m sprints with splits taken at 5, 10, 20, and 30 m. Pearson’s product moment correlations were used to assess the relationships between measures, and independent samples t tests were used to determine whether differences existed in sprint ability of those in the top and bottom quartiles for force at 100 ms, CMJ, and RSI. Significant negative moderate correlations were reported between force at 100 ms and 0–5 m and 5–10 m, significant moderate and large negative correlations between CMJ and all splits and significant large correlations between RSI and splits over 5 m. Force at 100 ms distinguished between performance levels from 0 to 5 m, CMJ from 10 to 20 m, and RSI from 20 to 30 m; faster subjects produced significantly higher force, JHs, and RSI scores. Three principal components explaining 86.1% of the variation in the data set were identified: sprint times and stretch shortening cycle capabilities (33.3%), time-specific force (29.9%), and absolute and relative strength (22.8%).
... 13,14 Moreover, it has been shown that specific leg strength can be important for specific sprint sections, e.g., whole leg extension capability can be important for the initial acceleration, while ankle reactive strength capability can be essential for the section approaching the maximal speed. 15 Thus, investigating the underlying variables of sprinting in multiple sections of the entire sprinting could deepen our understanding of TFS on dynamic movement performance. ...
... The jump tests were performed in accordance with a previous study. 15 All jump tests were performed without arm swing action. Two trials were performed for SJ and CMJ, and the best trial based on the jump height was used for the statistical analysis. ...
... The RJ was measured for jump height, contact time, and jump index; i.e., the ratio of the jump height (m) divided by the contact time (s). 15 The TFS was measured as maximal isometric toe grip strength using a specific measurement device (T.K.K.3364, Takei Scientific Instruments, Niigata) (Fig. 1A). 1,5,20 The measurement was performed in a seated position with hip, knee and ankle angles being 90 degrees (Fig. 1A). ...
Objectives: This study aimed to investigate the influence of increases in toe-flexor strength (TFS) through specific training on sprint and jump performances. Design: This study conducted 8 weeks of training with a two-period cross-over design. Methods: Eleven male sprinters performed TFS training (4 weeks, four times per week) which consisted of 6 strength exercises, and 60-m sprint, squat (SJ), countermovement (CMJ) and rebound continuous jumps (RJ), and TFS normalized to body mass were measured before and after the training period. Spatiotemporal and ground reaction force (GRF) variables during the 60-m sprint were also obtained. Results: There were no significant correlations of the normalized TFS with 50-m sprint time (r = 0.363, p = 0.272), SJ (r = 0.119, p = 0.728) and CMJ heights (r = −0.041, p = 0.906), and RJ height (r = 0.368, p = 0.266), contact time (r = −0.215, p = 0.526) and index (r = 0.380, p = 0.249) at the first measurement. Through the TFS training, normalized TFS increased from 0.331 ± 0.071 kg/kg to 0.384 ± 0.086 kg/kg (16.0%) for the average of two feet. All the sprint and jump performances, as well as the spatiotemporal and GRF variables during sprinting, did not show statistically significant changes through TFS training. Conclusions: These results indicate that, whereas 4 weeks of TFS training could increase normalized TFS for well-trained sprinters, the increase in normalized TFS could not be effective for improving sprint and jump performances for well-trained sprinters.
... In addition, many previous studies reported that vertical jump height in jumps such as countermovement jumps and squat jumps was increased by caffeine supplementation (5,6,14,15,18), and two meta-analyses suggested positive effects on jump performance (19,20). The heights of countermovement jumps and squat jumps are associated with sprint time in 60-m sprint running and maximum velocity in 100-m sprint running (21)(22)(23). Therefore, we hypothesized that caffeine supplementation would enhance 100-m sprint running performance by increasing the running velocity for the first 60 m, including the maximum velocity. ...
... In addition, caffeine supplementation enhanced the sprint velocity in the first 20 m of the 100-m sprint. This result indicated that caffeine positively acted on sprint performance in the acceleration phase of the 100-m sprint, especially in the early stage of the acceleration phase (23). As the mechanisms of caffeine's effects on sports performance, central factors, such as effects on adenosine receptors in the central nervous system, and peripheral factors, such as direct effects on skeletal muscle, have been considered (35)(36)(37), but these effects are controversial. ...
Purpose:
No study has assessed the acute effect of caffeine supplementation on 100-m sprint running in athletics, and caffeine's net ergogenicity on 100-m sprint running remains unclear. We investigated the acute effects of caffeine supplementation on 100-m sprint running performance in a field test.
Methods:
Thirteen male collegiate sprinters were subjected to 100-m sprint running time trials (TT) after the ingestion of 6 mg·kg-1 body weight caffeine or placebo supplementation in a double-blind, counterbalanced, randomized, and crossover design. Sprint velocity was measured with a laser system, and sprint time was calculated from the data in which the effects of environmental factors that would act as confounding factors on sprint time during TT were eliminated.
Results:
The corrected 100-m sprint time was significantly shortened by 0.14 sec with caffeine supplementation compared with placebo (placebo: 11.40 ± 0.39 sec, caffeine: 11.26 ± 0.33 sec, P = 0.007, g = -0.33). The corrected sprint time up to 60 m during TT was also significantly shorter with caffeine supplementation than with placebo (P = 0.002). Furthermore, the mean sprint velocity for 0-10 and 10-20 m splits was significantly increased by caffeine supplementation (all P < 0.05).
Conclusions:
Acute caffeine supplementation enhanced the corrected 100-m sprint time by improving the sprint performance in the first 60 m following more explosive acceleration in the early stage of the acceleration phase. Thus, for the first time, we directly demonstrated caffeine's ergogenicity on 100-m sprint performance in athletics.
... 13,16 Para as relações entre corrida de alta velocidade e salto bilateral, foi indicada a característica de SSC no DJ, que gera alta potência durante a fase excêntrica, com ângulo de joelho relativamente menor que se assemelha ao padrão de movimento mecânico do sprint em Vmáx. 17 10,19 Outros estudos relataram relações moderadas entre Vmáx e SJ (r = 0,56 a 0,64). 5,[14][15][16][17] Esses dados concordam parcialmente com nosso estudo. ...
... 1,10-14 Também foi encontrada relação significativa entre SJ e sprint de 7 a 18 m em velocistas do sexo masculino. 19 No DJ, a altura foi significativamente correlacionada com 5 m. Katja e Coh 14 relataram que altura do DJ foi correlacionada com a Vmáx da corrida de sprint de 20 m. ...
Objectives
This study aimed to examine the relationship between vertical jumping at forces of specific time phase and sprint performance in teenage sprinters.
Methods
Fifteen male teenage sprinters (age: 14±2 years, height: 168±2 cm, weight: 61±1 kg) participated in the study. The subjects performed the following bilateral/unilateral jumps on a force platform: a) squat jump (SJ), b) unilateral SJ (USJ), c) 40cm drop jump (DJ), and d) 20cm unilateral DJ (UDJ). The 60m sprint test was administered on the second day. Brower split timers were positioned to record subjects’ 5m, 10m, 50m and 60m split times. The variables for inclusion were vertical jump height, maximum force, and force output at 120ms in all jumps and sprint time measures.
Results
The results of the Pearson Product Moment Correlation analysis showed that SJ120ms was correlated to 5m and USJ120ms was correlated to 10m. UDJ120ms showed a stronger correlation with 50m than DJ120ms. Although significant correlations using maximum force and height were observed, there were inconsistent results between bilateral and unilateral jumps.
Conclusion
Our results highlighted that jumps that have similar form with certain force outputs at specific event timing could more precisely predict sprint performance in teenage sprinters. USJ120ms and UDJ120ms could better predict the acceleration (10m) and high-speed phase (50m) in sprint performance, respectively. Moreover, coaches and practitioners should be cautious when using only jump height or maximum force to predict sprint performance, since the results could be inaccurate when specific movement variables are not thoughtfully considered. Level of evidence III.
Keyword:
Acceleration; Athletic performances; Plyometric exercise
... r=0.65). 10,19 Other studies have reported moderate relationships between Vmax and SJ (r = 0.56 to 0.64). 5,[14][15][16][17] These data are in partial agreement with our study. ...
... 1,10-14 Significant relationship was also found between SJ and 7-18m sprint in male sprinters. 19 In DJ, DJH was significantly correlated to 5m. Katja and Coh 14 stated DJH was correlated with in Vmax 20-m sprint running. ...
Objectives
This study aimed to examine the relationship between vertical jumping at forces of specific time phase and sprint performance in teenage sprinters.
Methods
Fifteen male teenage sprinters (age: 14±2 years, height: 168±2 cm, weight: 61±1 kg) participated in the study. The subjects performed the following bilateral/unilateral jumps on a force platform: a) squat jump (SJ), b) unilateral SJ (USJ), c) 40cm drop jump (DJ), and d) 20cm unilateral DJ (UDJ). The 60m sprint test was administered on the second day. Brower split timers were positioned to record subjects’ 5m, 10m, 50m and 60m split times. The variables for inclusion were vertical jump height, maximum force, and force output at 120ms in all jumps and sprint time measures.
Results
The results of the Pearson Product Moment Correlation analysis showed that SJ120ms was correlated to 5m and USJ120ms was correlated to 10m. UDJ120ms showed a stronger correlation with 50m than DJ120ms. Although significant correlations using maximum force and height were observed, there were inconsistent results between bilateral and unilateral jumps.
Conclusion
Our results highlighted that jumps that have similar form with certain force outputs at specific event timing could more precisely predict sprint performance in teenage sprinters. USJ120ms and UDJ120ms could better predict the acceleration (10m) and high-speed phase (50m) in sprint performance, respectively. Moreover, coaches and practitioners should be cautious when using only jump height or maximum force to predict sprint performance, since the results could be inaccurate when specific movement variables are not thoughtfully considered. Level of evidence III.
Keyword:
Acceleration; Athletic performances; Plyometric exercise
... Fourth, the participants completed an exhausting pedalling test in which the speed and power of the bike were simultaneously increased every 1 minute until volitional tiredness, followed by blood CK level measurements (Chen et al., 2021). The counter-movement jump (CMJ) and squat jump (SJ) are two vertical jump motions that are commonly used to assess athletic performance (Nagahara et al., 2014;Van Hooren & Zolotarjova, 2017). They offer a meaningful and consistent measurement of lower-body explosive power (Markovic et al., 2004). ...
... Also, in some studies, anaerobic exercise was used to measure RPE and a significant reduction in RPE was observed (Caldwell et al., 2018). The differential effects may be related to the type of exercise performed as RPE is highly correlated with HR, respiration, and ventilation during an aerobic exercise whereas RPE during anaerobic exercise is largely related to the buffering capacity of skeletal muscle (Gamberale, 1972;Lagally et al., 2002;Noble & Robertson, 1996;Scherr et al., 2013). ...
This review sought to assess the dose-response, i.e., low (<300 mg/day) and high (>300 mg/day), and temporal effects of ginseng, i.e., immediate, short-term (up to 4 weeks) and long-term (>4 weeks) in comparison to placebo on physical performance [visual analogue scale (VAS) level, vertical jump(VJ), rating of perceived exertion (RPE), peak power output (PPO)] and physiological measures [VO2 max, creatine kinase(CK), heart rate(HR)], in athletes and active participants. Search in four databases with English language constraints yielded 492 studies. Fourteen studies were shortlisted through PEDro scale by methodological quality evaluation. Ginseng exhibited significant short-term effect at high dosage for VJ improvement (SMD: -8.17, 95% CI: -16.28 to -0.06, p= 0.05). Ginseng had no effect on VAS (SMD: -0.65, 95% CI: -1.35 to 0.06, p= 0.07), RPE (SMD: -1.11, 95% CI: -2.57 to 0.35, p= 0.14), PPO (SMD: -0.70, 95% CI: -1.78 to 0.38, p= 0.20), HR (SMD: -0.54, 95% CI: -2.05 to 0.96, p= 0.48), CK (SMD: 0.33, 95% CI: -0.18 to 0.84, p= 0.21) and VO2 max (SMD: 0.08, 95% CI: -0.69 to 0.85, p= 0.08).The ginseng supplementation was found to have significant short-term effect at high dose only for VJ in athletic and active participants. Methodologically strong research is warranted to further consolidate these findings.
... This index is widely used in research and assessment of athletes because it can be measured with a high accuracy [5][6][7][8][9]. Athletes with high athletic performance have higher performance variables, such as the RJindex [4,10]. Especially, it has been reported that the RJ-index are related to athletic activities, such as sprinting [10][11][12][13][14], change of direction [15,16]. ...
... Athletes with high athletic performance have higher performance variables, such as the RJindex [4,10]. Especially, it has been reported that the RJ-index are related to athletic activities, such as sprinting [10][11][12][13][14], change of direction [15,16]. Thus, the significance of increasing the RSI and RJ-index has been shown; however, methods to improve these indices by training are not well-known [5,9,17]. ...
... All subjects performed the RJ at least three times as a warm-up. The RJ involved repeated jumps and was performed with six jumps [10,19]. The participants were instructed to jump as high as possible and keep the contact time as short as possible. ...
The stretch-shortening cycle (SSC) motor execution ability of the lower limb was measured using the rebound jump index (RJ-index) in RJ test; this performance is influenced by the interaction of the forces exerted by the three joints of the lower limb.We aimed to determine RJ performance variables and identify the lower limb kinetic variables that affect them. One hundred two female university students (age, 20.1±1.0 years; height, 164.6±7.2 cm; mass, 58.9±7.3 kg) for whom RJ performance variables (RJ-index, jump height, and contact time) and joint kinetics (torque, power, and work) were measured. Statistical analysis showed a strong correlation between the RJ-index and jump height or contact time (r = 0.920, -0.726, p < 0.05) but a weak correlation between the jump height and contact time (r = -0.384, p < 0.05). Furthermore, positive ankle power was the most influential factor for RJ performance variables; additionally, positive knee power and hip work and eccentric knee torque significantly influenced jump height, and positive ankle power, negative work and power, and concentric torque significantly influenced the contact time. The acquisition of the jump height and a shorter contact time requires different kinetic variables. Furthermore, the characteristics of the force exerted by the three joints of the lower limb that compose the RJ-index may be different even if the RJ-index has the same value. Therefore, by assessing not only the RJ-index but also the jump height, contact time, and characteristics of lower limb joint kinetics in the RJ test, it is possible to conduct effective training to improve lower limb SSC motor execution performance according to individual characteristics.
... Therefore, the aim of the study is to investigate the relationships of the conventional H/Q ratio with sprint times (10-and 30-m) and jumps height (CMJ and SJ) in elite young soccer players. Additionally, based on previous reports [12,16,[37][38][39], it can be expected that significant relationships should be found between speed abilities (10-and 30 m sprint times) and jumping abilities (CMJ and SJ heights), the two key abilities for scoring goals. Therefore, it is hypothesized that players who can jump higher should be characterized by shorter sprinting times. ...
... No significant relationships were observed between sprint times (10-and 30-m) and jump heights (CMJ and SJ) in the study group of soccer players. In many previous studies, significant negative relationships were found between jumping and sprinting performances [16,38,39]. Vescovi and McGuigan [55] noted that the relationships between CMJ height and linear sprint times were stronger at longer distances (27.4 and 36.6 m) than at shorter distances (9.1 and 18.3 m). ...
The correct torque ratio between the knee joint extensor and flexor muscle groups can effectively prevent injuries to the anterior cruciate ligament and hamstring strain. However, it is unclear whether a high torque ratio of the knee joint flexor muscles to the extensor muscles is beneficial for sport performance. Therefore, the aim of the study was to investigate the relationshipbetween the hamstring-to-quadriceps (H/Q) ratio and sprint times (10- and 30-m) and jump heights (CMJ and SJ) in soccer players. The study examined 26 young elite soccer players (age: 18.1 ± 0.7 years; body height: 1.77 ± 0.05 m; body mass: 72.7 ± 5.7 kg). Knee joint flexor and extensor peak torques were assessed using the Cybex dynamometer (at 60◦/s, 120◦/s and 180◦/s). Additionally, each participant performed the CMJ, SJ, and 30 m sprint. A significant relationship was obtained between the H/Q ratio (60◦/s) and 30 m sprint time (r = 0.47). The positive direction of this relationship may indicate an important role of knee joint extensors in sprinting performance. Moreover, the H/Q ratio was not significantly associated with the CMJ, SJ or 10 m sprint performance. The H/Q ratio should be considered together with the peak torque values in terms of the assessment of sprinting and jumping performance.
