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A review advocating caution with Major League Soccer expansion and investment in more rehabilitation professionals
Abstract
Background and purpose:
Major League Soccer (MLS) has aggressively expanded from 10 teams to 23 teams. With the addition of more teams, the league will have to dictate a schedule that maximizes the league's popularity, while also maintaining the health of the players. A longer season and congested game schedule could increase the risk of injury for players. The purpose of this commentary is to make recommendations for the prevention of injuries among MLS players with respect to proposed league expansion.
Description of topic:
MLS has lengthened the regular season with each expansion in teams. An increase in season length was seen in conjunction with the MLS expansion from 14 to 19 teams during the 2008 through 2013 seasons. Data from the inaugural MLS season found injury rates were higher in games compared to practices and more injuries occurred later in the season. With the expansion of MLS, anterior cruciate ligament tears appeared to have increased each year.
Discussion:
Current evidence suggests the implementation of a proper preseason in addition to the once-per-week game frequency would best promote player health and well-being. Players may benefit from in-season injury prevention training and weekly load monitoring.
... The magnitude of physical stress on the skeletal muscle system can be inferred by measuring the plasma creatine kinase (CK) and skin temperature by thermal images to determine changes in response to physiological processes or pathological reactions related to training and/ or matches [18,25]. Measuring the physical stress involving the implementation of single combined techniques is important to develop recovery strategies that might accelerate the time to achieve full recovery as well as reduce the risk of injury [23,26]. ...
Study aim : This study compared the effects of intermittent negative pressure therapy (INPT) vs. active recovery therapy (ART) on post-match physiological parameters such as serum CK level and skin temperature of the lower limbs in elite soccer players.
Material and methods : Twenty healthy male professional soccer players from a Brazilian first division soccer club were enrolled in this randomized, parallel arm, open label, comparative study. After participating in 2 soccer matches, they were randomly assigned to two groups (n = 10) to receive a 30-min session of INPT (intermittent exchange of hypobaric pressure range 33 to 51 mmHg) or ART (self-myofascial release, mobility and stability exercises, and cycle ergometer exercise). The intervention was conducted after a match with assessments immediately before and after the intervention and again 24 h after the intervention.
Results : A significant interaction effect (F 2,36 = 4.503, p = 0.018, η ² = 0.130) was observed, indicating that the decrease of CK from pre-intervention to 24 h post-intervention was greater in the INPT than in the ART group. Lower limb skin temperature was significantly lower after INPT than after ART (p < 0.003).
Conclusions : Serum CK level and skin temperature of lower limbs showed better recovery up to 24 h after the intervention with INPT in elite soccer players.
Context:
It is well demonstrated that Nordic hamstring (NH) program has poor compliance across European soccer clubs, but little is known about its implementation in Major League Soccer (MLS). The authors aimed to investigate MLS hamstring prevention practices and compliance with the NH program and understand the reasons for its inclusion or exclusion.
Design:
A cross-sectional electronic survey was completed by 24 of the 26 (92%) MLS top-division soccer clubs.
Methods:
The survey, based on the Reach, Efficacy, Adoption, Implementation, and Maintenance framework, was sent to team medical staff. Medical staff were also asked for opinions on barriers to implementation.
Results:
Eighteen clubs (75%) reported a formal hamstring injury prevention program, with eccentric exercises (94%; 95% CI [confidence interval], 74%-99%), high-speed running (94%; 95% CI, 74%-99%), and NH exercises (89%; 95% CI, 67%-97%) the most common strategies adopted. Fifteen clubs partially implemented the NH program, but only 5 (21%; 95% CI, 9%-40%) completed the full program and were classed as compliant. A total of 20 respondents reported that player perception and muscle soreness (83%; 95% CI, 64%-93%) were barriers to the implementation of the NH program. On a 5-point Likert scale, respondents "partially agreed" (4.13 [0.80]) that the NH exercise could substantially reduce injuries and would be "effective" at their own club (3.88 [0.61]).
Conclusions:
The NH exercise was valued, but negative player perception and muscular soreness were identified as barriers to implementing the full program. Manipulation of volume and frequency should inform future "effectiveness" research to prospectively assess such modifications in the context of MLS.
Background
Clinically it is understood that rapid increases in training loads expose an athlete to an increased risk of injury; however, there are no systematic reviews to qualify this statement. Objective
The aim of this systematic review was to determine training and competition loads, and the relationship between injury, illness and soreness. Methods
The MEDLINE, SPORTDiscus, CINAHL and EMBASE databases were searched using a predefined search strategy. Studies were included if they analysed the relationship between training or competition loads and injury or illness, and were published prior to October 2015. Participants were athletes of any age or level of competition. The quality of the studies included in the review was evaluated using the Newcastle–Ottawa Scale (NOS). The level of evidence was defined as strong, ‘consistent findings among multiple high-quality randomised controlled trials (RCTs)’; moderate, ‘consistent findings among multiple low-quality RCTs and/or non-randomised controlled trials (CCTs) and/or one high-quality RCT’; limited, ‘one low-quality RCT and/or CCTs, conflicting evidence’; conflicting, ‘inconsistent findings among multiple trials (RCTs and/or CCTs)’; or no evidence, ‘no RCTs or CCTs’. ResultsA total of 799 studies were identified; 23 studies met the inclusion criteria, and a further 12 studies that were not identified in the search but met the inclusion criteria were subsequently added to the review. The largest number of studies evaluated the relationship between injuries and training load in rugby league players (n = 9) followed by cricket (n = 5), football (n = 3), Australian Football (n = 3), rugby union (n = 2),volleyball (n = 2), baseball (n = 2), water polo (n = 1), rowing (n = 1), basketball (n = 1), swimming (n = 1), middle-distance runners (n = 1) and various sports combined (n = 1). Moderate evidence for a significant relationship was observed between training loads and injury incidence in the majority of studies (n = 27, 93 %). In addition, moderate evidence exists for a significant relationship between training loads and illness incidence (n = 6, 75 %). Training loads were reported to have a protective effect against injury (n = 9, 31 %) and illness (n = 1, 13 %). The median (range) NOS score for injury and illness was 8 (5–9) and 6 (5–9), respectively. LimitationsA limitation of this systematic review was the a priori search strategy. Twelve further studies were included that were not identified in the search strategy, thus potentially introducing bias. The quality assessment was completed by only one author. Conclusions
The results of this systematic review highlight that there is emerging moderate evidence for the relationship between the training load applied to an athlete and the occurrence of injury and illness. ImplicationsThe training load applied to an athlete appears to be related to their risk of injury and/or illness. Sports science and medicine professionals working with athletes should monitor this load and avoid acute spikes in loads. It is recommended that internal load as the product of the rate of perceived exertion (10-point modified Borg) and duration be used when determining injury risk in team-based sports. External loads measured as throw counts should also be monitored and collected across a season to determine injury risk in throwing populations. Global positioning system-derived distances should be utilised in team sports, and injury monitoring should occur for at least 4 weeks after spikes in loads.
Background:
The treatment and rehabilitation procedures of anterior cruciate ligament (ACL) injuries in elite soccer players are controversial. Points of debate include surgical timing, technique, graft choice, rehabilitation, and return-to-sport criteria and timing.
Purpose:
To identify practice preferences among current Major League Soccer (MLS) team orthopaedic surgeons for ACL injuries.
Study design:
Cross-sectional study; Level of evidence, 4.
Methods:
The survey was administered at the MLS team physician annual meeting in January 2013. At least 1 orthopaedic surgeon representative from each of the 19 clubs (16 from the United States, 3 from Canada) was in attendance. Teams with more than 1 affiliated orthopaedic surgeon were given an additional survey to be completed either at the meeting or returned via e-mail. Descriptive statistics, Wilcoxon Mann-Whitney (return-to-play parameters, running, and ball drills), and Fisher exact tests (graft selection, bracing, continuous passive motion) were applied to the various data sets from the survey responses.
Results:
A 100% survey participation rate was achieved (22 team orthopaedic surgeons representing 19 MLS teams). A single-incision, arthroscopically assisted, single-bundle reconstruction was the most common technique (91%). Surgeons were split regarding femoral tunnel drilling (50% transtibial, 46% accessory medial). Autograft bone-patellar tendon-bone (BPTB) was the most common preferred graft choice (68%). The biggest concerns about BPTB autograft and hamstring autograft were anterior knee pain (76%) and hamstring weakness (46%), respectively. Most surgeons did not recommend postoperative continuous passive motion (64%) or functional bracing (68%). Most surgeons permitted return to sport without restrictions at 6 to 8 months following surgery (82%). Surgeons who routinely used functional bracing after ACL surgery more frequently used hamstring autograft than those who used BPTB autograft (P = .04).
Conclusion:
This article successfully describes current management of ACL injuries among MLS team orthopaedic surgeons. The preference for single-bundle BPTB autograft is similar to published data in the National Football League and National Basketball Association.
The purpose of this study was to describe professional soccer players' perceptions towards injuries, physical recovery and the effect of surface related factors on injury resulting from soccer participation on 3rd generation artificial turf (FT) compared to natural grass (NG).
Information was collected through a questionnaire that was completed by 99 professional soccer players from 6 teams competing in Major League Soccer (MLS) during the 2011 season.
The majority (93% and 95%) of the players reported that playing surface type and quality influenced the risk of sustaining an injury. Players believed that playing and training on FT increased the risk of sustaining a non-contact injury as opposed to a contact injury. The players identified three surface related risk factors on FT, which they related to injuries and greater recovery times: 1) Greater surface stiffness 2) Greater surface friction 3) Larger metabolic cost to playing on artificial grounds. Overall, 94% of the players chose FT as the surface most likely to increase the risk of sustaining an injury.
Players believe that the risk of injury differs according to surface type, and that FT is associated with an increased risk of non-contact injury. Future studies should be designed prospectively to systematically track the perceptions of groups of professional players training and competing on FT and NG.
Background: Anterior cruciate ligament (ACL) rupture is a significant injury in male Major League Soccer (MLS) players in the United States.
Purpose: To determine (1) return-to-sport (RTS) rate in MLS following ACL reconstruction (ACLR), (2) timing of RTS, (3) performance upon RTS, and (4) the difference in RTS and performance between players who underwent ACL reconstruction (ACLR) and controls.
Study Design: Case-control study; Level of evidence, 3.
Methods: MLS players undergoing ACLR between 1996 and 2012 were evaluated. Player data were extracted from publically available sources. All demographic data were analyzed. A control group of players matched by age, body mass index (BMI), sex, position, performance, and MLS experience (occurred at 2.6 years into career, designated ‘‘index year’’) was selected from the MLS during the same years as those undergoing ACLR. The RTS and performance in the MLS were analyzed and compared between cases and controls. Student t tests were performed for analysis of within- and between-group variables.
Results: A total of 52 players (57 knees) that met inclusion criteria underwent ACLR while in the MLS. Mean player age was 25.6+/- 3.98 years. Forty players were able to resume play (77%). Of the 40 players (45 knees), 38 (43 knees; 95%) resumed play the season following ACLR (mean, 10+/-2.8 months after surgery). Mean career length in the MLS after ACLR was 4.0+/-2.8 years. The revision rate was 10%. There was a significant increase in the incidence of ACL tears in the MLS by year (P < .001), and there was a
significantly (P = .002) greater number of ACL tears on the left knee as opposed to the right. Performance in the MLS upon RTS after ACLR was not significantly different versus preinjury. There was no significant difference in survival in the MLS between cases and controls after ACLR or index year. The only significant performance differences between cases and controls were that cases had significantly greater shots taken per season (P = .005) and assists (P = .005) than did controls after the index year.
Conclusion: There is a high RTS rate in the MLS following ACLR. Nearly all players resumed play the season after surgery. Performance was not significantly different from preinjury. Only 2 performance measures (shots taken and assists) were significantly different between cases and controls. A significantly greater number of ACL tears occur in the left versus the right knee.
Keywords: anterior cruciate ligament; Major League Soccer; return to sport; knee
Use of Global positioning system (GPS) technology in team sport permits measurement of player position, velocity, and movement patterns. GPS provides scope for better understanding of the specific and positional physiological demands of team sport and can be used to design training programs that adequately prepare athletes for competition with the aim of optimizing on-field performance.
The objective of this study was to conduct a systematic review of the depth and scope of reported GPS and microtechnology measures used within individual sports in order to present the contemporary and emerging themes of GPS application within team sports.
A systematic review of the application of GPS technology in team sports was conducted. We systematically searched electronic databases from earliest record to June 2012. Permutations of key words included GPS; male and female; age 12-50 years; able-bodied; and recreational to elite competitive team sports.
The 35 manuscripts meeting the eligibility criteria included 1,276 participants (age 11.2-31.5 years; 95 % males; 53.8 % elite adult athletes). The majority of manuscripts reported on GPS use in various football codes: Australian football league (AFL; n = 8), soccer (n = 7), rugby union (n = 6), and rugby league (n = 6), with limited representation in other team sports: cricket (n = 3), hockey (n = 3), lacrosse (n = 1), and netball (n = 1). Of the included manuscripts, 34 (97 %) detailed work rate patterns such as distance, relative distance, speed, and accelerations, with only five (14.3 %) reporting on impact variables. Activity profiles characterizing positional play and competitive levels were also described. Work rate patterns were typically categoriszed into six speed zones, ranging from 0 to 36.0 km·h(-1), with descriptors ranging from walking to sprinting used to identify the type of activity mainly performed in each zone. With the exception of cricket, no standardized speed zones or definitions were observed within or between sports. Furthermore, speed zone criteria often varied widely within (e.g. zone 3 of AFL ranged from 7 to 16 km·h(-1)) and between sports (e.g. zone 3 of soccer ranged from 3.0 to <13 km·h(-1) code). Activity descriptors for a zone also varied widely between sports (e.g. zone 4 definitions ranged from jog, run, high velocity, to high-intensity run). Most manuscripts focused on the demands of higher intensity efforts (running and sprint) required by players. Body loads and impacts, also summarized into six zones, showed small variations in descriptions, with zone criteria based upon grading systems provided by GPS manufacturers.
This systematic review highlights that GPS technology has been used more often across a range of football codes than across other team sports. Work rate pattern activities are most often reported, whilst impact data, which require the use of microtechnology sensors such as accelerometers, are least reported. There is a lack of consistency in the definition of speed zones and activity descriptors, both within and across team sports, thus underscoring the difficulties encountered in meaningful comparisons of the physiological demands both within and between team sports. A consensus on definitions of speed zones and activity descriptors within sports would facilitate direct comparison of the demands within the same sport. Meta-analysis from systematic review would also be supported. Standardization of speed zones between sports may not be feasible due to disparities in work rate pattern activities.