Hamstring Injury Prevention Practices in Elite Sport: Evidence for Eccentric Strength vs. Lumbo-Pelvic Training

Epidemiology of Hamstring Tears in National Collegiate Athletic Association Athletes: Findings From the National Collegiate Athletic Association Injury Surveillance Program Between 2014/2015 and 2018/2019

OBJECTIVE

To describe the epidemiology of hamstring tears in National Collegiate Athletic Association (NCAA) sports.

DESIGN

Descriptive epidemiology study. Athletic trainers from NCAA schools reported injuries to the NCAA Injury Surveillance Program.

SETTING

A convenience sample of NCAA hamstring tear injuries during the 2014/2015 through 2018/2019 academic years.

PATIENTS OR PARTICIPANTS

NCAA student-athletes.

INDEPENDENT VARIABLES

Sport, sex, event type, season segment, injury history, and activity at the time of injury.

MAIN OUTCOME MEASURES

Injury counts, rates, and proportions were used.

RESULTS

Two thousand ninety-six hamstring tears from 8 474 400 athlete-exposures (AEs) were reported (2.47 per 10 000 AEs). Rates were highest in Men's Soccer (5.97 per 10 000 AEs) and Women's Soccer (3.13 per 10 000 AEs), among all Men's and Women's sports, respectively. Competition-related rates in Men's and Women's sports were highest in 2015 to 2016 then followed a decreasing pattern across the remainder of the study period. Among sex-comparable sports, rates were higher in men's (compared with women's) Baseball/Softball, Soccer, and Track and Field. The prevalence of recurrent injuries was comparable among men's (14.8%) and women's (11.5%) sports. Time loss hamstring tears were more prevalent in Men's sports than Women's sports [injury proportion ratio = 1.33; 95% confidence interval, (1.21, 1.47)].

CONCLUSIONS

Overall, hamstring tear rates were higher across all Men's sports compared with Women's sports. Rates across event type were comparable in several sports; and so, adjustments to practice are needed considering that practice environments are more modifiable than competitions. Indeed, improving hamstring tear prevention programs to reduce the burden of this injury in NCAA athletes remains critical.

Hamstring Strain Injury Prevention: Current Beliefs and Practices of Practitioners Working in Major League Baseball

CONTEXT

Hamstring strain injury (HSI) is the most frequently sustained injury in Major League Baseball (MLB). However, the beliefs and practices of practitioners working in MLB regarding HSI risk factors and prevention strategies in baseball athletes have not been documented.

OBJECTIVE

To document the current beliefs and practices of practitioners working in MLB regarding HSI prevention.

DESIGN

Cross-sectional study.

SETTING

Major League Baseball via an online survey.

PATIENTS OR OTHER PARTICIPANTS

Athletic trainers, physical therapists, and strength and conditioning coaches working in MLB during the 2021 season.

DATA COLLECTION AND ANALYSIS

An online survey was conducted, with participants completing the survey once. Questions pertained to risk factor identification, the use and perceived effectiveness of prevention strategies, and barriers to implementation. Descriptive statistics were calculated for each question.

RESULTS

A total of 91 responses were received featuring respondents from 28 of 30 MLB organizations. The perceived most important intrinsic risk factors were tolerance to high-speed running for first-time HSI and previous HSI for recurrent injury. The perceived most important extrinsic risk factor for both first-time and recurrent HSI was internal communication between staff. The perceived most effective prevention strategies were managing overall workload, regular exposure to high-speed running, and periodization. The most used prevention strategies were core or lumbopelvic strengthening, traditional resistance-training exercises, and managing overall workload. Approximately half (53%) of respondents reported barriers to effective implementation of HSI prevention strategies, including player and coach buy-in, compliance, workload management, and scheduling.

CONCLUSIONS

This was the first survey to investigate MLB practitioner beliefs and practices regarding HSI prevention. Responses from practitioners regarding their beliefs about risk factors and appropriate prevention strategies varied, and discrepancies existed between the perceived most effective strategies and those most frequently used.

Effectiveness of Injury Prevention Programs With Core Muscle Strengthening Exercises to Reduce the Incidence of Hamstring Injury Among Soccer Players: A Systematic Review and Meta-Analysis

CONTEXT

Muscles in the hamstring group are frequently injured in sporting activities. Injury prevention programs (IPPs), including eccentric training of the hamstrings, have proven to be of great value in decreasing the injury rate of hamstring muscles.

OBJECTIVE

To examine the effectiveness of IPPs that include core muscle strengthening exercises (CMSEs) in reducing hamstring injury rates.

DATA SOURCES

This systematic review with meta-analysis was based upon the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A systematic search was conducted for relevant studies published from 1985 to 2021 using the following databases: Cochrane Library, MEDLINE, AMED, PubMed, Web of Science, and Physiotherapy Evidence Database (PEDro).

STUDY SELECTION

The initial electronic search found 2694 randomized controlled trials (RCTs). After removing duplicate entries, 1374 articles were screened by their titles and abstracts, and 53 full-text records were assessed, of which 43 were excluded. The remaining 10 articles were reviewed in detail, from which 5 studies met our inclusion criteria and were included in the current meta-analysis.

STUDY DESIGN

Systematic review and meta-analysis of RCTs.

LEVEL OF EVIDENCE

Level 1a.

DATA EXTRACTION

Two researchers independently completed the abstract review and performed full-text reviews. A third reviewer was consulted to reach a consensus if any discrepancies were noted. Details were recorded about the participants, methodological aspects, eligibility criteria, intervention data, and outcome measures, including age; number of subjects in the intervention/control group; number of injuries in each group; and the duration, frequency, and intensity of the training conducted in the intervention.

RESULTS

The pooled results of 4728 players and 379,102 exposure hours showed 47% hamstring injury reduction per 1000 h of exposure in the intervention group compared with the control group with an injury risk ratio of 0.53 (95% CI [0.28, 0.98], P = 0.04).

CONCLUSION

The results indicate that CMSEs incorporated with IPPs reduce susceptibility and risk of hamstring injuries in soccer players.

Medical ozone on hamstring injury in a professional athlete assessed by thermography: a clinical case report

Injuries associated with the hamstring muscles in the running athlete are increasingly investigated due to the economic and functional consequences associated with them. Although hardly used in the treatment of sports injuries, medical ozone is effective and very well tolerated in the treatment of musculoskeletal pain, it was decided to add a series of medical ozone infiltrations to the treatment. The evolution of the case was recorded by medical thermography, in addition to measuring pain intensity (visual analog scale) and functional capacity (toe touch test). Pain intensity (visual analog scale) decreased from seven at baseline to two at the end of treatment (after two ozone infiltrations, one weekly). Mobility of the damaged area (toe touch test) improved from a distance of 8 cm at baseline to 0 cm at the end of treatment. Regarding medical thermography, after the first and second infiltration of ozone, the temperature rose to a significant increase in perfusion from baseline from 31.2 to 31.8 °C and from 31.2 to 32 °C, respectively. These results suggest the possible interest of medical ozone as an adjuvant treatment for the recovery of sports tendinopathies and encourage us to carry out further studies.

How are hamstring strain injuries managed in elite men's football clubs? A survey with 62 Brazilian physical therapists

OBJECTIVE

To describe perceptions and practices of physical therapists from elite men's football clubs on the management of athletes with hamstring strain injury (HSI).

DESIGN

Cross-sectional study.

SETTING

Online survey.

PARTICIPANTS

Physical therapists from clubs engaged in the two main divisions of Brazilian men's football.

MAIN OUTCOME MEASURES

Practices for assessment and rehabilitation of athletes with HSI.

RESULTS

This survey had 62 physical therapists from 35 of the 40 eligible clubs (87.5% representativeness). Despite heterogeneity on assessment practices, all respondents use imaging exams, adopt injury classification scales, and evaluate aspects related to pain, range of motion, muscle strength, and functional status of athletes with HSI. Rehabilitation programs are usually divided into 3 to 4 phases. All respondents usually apply electrophysical agents and stretching in HSI rehabilitation programs, 98.4% apply strengthening exercises (93.5% include eccentrics), 96.8% manual therapy, 95.2% exercises that mimic the functional demands of football, and 93.5% lumbopelvic stabilization exercises. Muscle strength was the most reported return to play criterion (71% of respondents).

CONCLUSION

The present study allowed the sports physical therapy community to become aware of the approaches usually adopted for management of athletes with HSI who play in the highest level of Brazilian men's football.

London International Consensus and Delphi study on hamstring injuries part 3: rehabilitation, running and return to sport

Hamstring injuries (HSIs) are the most common athletic injury in running and pivoting sports, but despite large amounts of research, injury rates have not declined in the last 2 decades. HSI often recur and many areas are lacking evidence and guidance for optimal rehabilitation. This study aimed to develop an international expert consensus for the management of HSI. A modified Delphi methodology and consensus process was used with an international expert panel, involving two rounds of online questionnaires and an intermediate round involving a consensus meeting. The initial information gathering round questionnaire was sent to 46 international experts, which comprised open-ended questions covering decision-making domains in HSI. Thematic analysis of responses outlined key domains, which were evaluated by a smaller international subgroup (n=15), comprising clinical academic sports medicine physicians, physiotherapists and orthopaedic surgeons in a consensus meeting. After group discussion around each domain, a series of consensus statements were prepared, debated and refined. A round 2 questionnaire was sent to 112 international hamstring experts to vote on these statements and determine level of agreement. Consensus threshold was set a priori at 70%. Expert response rates were 35/46 (76%) (first round), 15/35 (attendees/invitees to meeting day) and 99/112 (88.2%) for final survey round. Statements on rehabilitation reaching consensus centred around: exercise selection and dosage (78.8%-96.3% agreement), impact of the kinetic chain (95%), criteria to progress exercise (73%-92.7%), running and sprinting (83%-100%) in rehabilitation and criteria for return to sport (RTS) (78.3%-98.3%). Benchmarks for flexibility (40%) and strength (66.1%) and adjuncts to rehabilitation (68.9%) did not reach agreement. This consensus panel recommends individualised rehabilitation based on the athlete, sporting demands, involved muscle(s) and injury type and severity (89.8%). Early-stage rehab should avoid high strain loads and rates. Loading is important but with less consensus on optimum progression and dosage. This panel recommends rehabilitation progress based on capacity and symptoms, with pain thresholds dependent on activity, except pain-free criteria supported for sprinting (85.5%). Experts focus on the demands and capacity required for match play when deciding the rehabilitation end goal and timing of RTS (89.8%). The expert panellists in this study followed evidence on aspects of rehabilitation after HSI, suggesting rehabilitation prescription should be individualised, but clarified areas where evidence was lacking. Additional research is required to determine the optimal load dose, timing and criteria for HSI rehabilitation and the monitoring and testing metrics to determine safe rapid progression in rehabilitation and safe RTS. Further research would benefit optimising: prescription of running and sprinting, the application of adjuncts in rehabilitation and treatment of kinetic chain HSI factors.

Numerical instability of Hill-type muscle models

Hill-type muscle models are highly preferred as phenomenological models for musculoskeletal simulation studies despite their introduction almost a century ago. The use of simple Hill-type models in simulations, instead of more recent cross-bridge models, is well justified since computationally 'light-weight'-although less accurate-Hill-type models have great value for large-scale simulations. However, this article aims to invite discussion on numerical instability issues of Hill-type muscle models in simulation studies, which can lead to computational failures and, therefore, cannot be simply dismissed as an inevitable but acceptable consequence of simplification. We will first revisit the basic premises and assumptions on the force-length and force-velocity relationships that Hill-type models are based upon, and their often overlooked but major theoretical limitations. We will then use several simple conceptual simulation studies to discuss how these numerical instability issues can manifest as practical computational problems. Lastly, we will review how such numerical instability issues are dealt with, mostly in an ad hoc fashion, in two main areas of application: musculoskeletal biomechanics and computer animation.

Hamstring Muscle Injuries and Hamstring Specific Training in Elite Athletics (Track and Field) Athletes

OBJECTIVE

We aimed to describe hamstring muscle injury (HMI) history and hamstring specific training (HST) in elite athletes. A secondary aim was to analyse the potential factors associated with in-championships HMI.

METHODS

We conducted a prospective cohort study to collect data before and during the 2018 European Athletics Championships. Injury and illness complaints during the month before the championship, HMI history during the entire career and the 2017-18 season, HST (strengthening, stretching, core stability, sprinting), and in-championship HMI were recorded. We calculated proportions of athletes with HMI history, we compared HST according to sex and disciplines with Chi2 tests or ANOVA, and analysed factors associated with in-championship HMI using simple model logistic regression.

RESULTS

Among the 357 included athletes, 48% reported at least one HMI during their career and 24% during the 2017-18 season. Of this latter group, 30.6% reported reduced or no participation in athletics' training or competition at the start of the championship due to the hamstring injury. For HST, higher volumes of hamstring stretching and sprinting were reported for disciplines requiring higher running velocities (i.e., sprints, hurdles, jumps, combined events and middle distances). Five in-championship HMIs were recorded. The simple model analysis showed a lower risk of sustaining an in-championships HMI for athletes who performed more core (lumbo-pelvic) stability training (OR = 0.49 (95% CI: 0.25 to 0.89), p = 0.021).

CONCLUSIONS

Our present study reports that HMI is a characteristic of the athletics athletes' career, especially in disciplines involving sprinting. In these disciplines, athletes were performing higher volumes of hamstring stretching and sprinting than in other disciplines. Further studies should be conducted to better understand if and how HST are protective approaches for HMI in order to improve HMI risk reduction strategies.

Predicting Hamstring Strains in Soccer Players Based on ROM: An Analysis From a Gender Perspective

Purpose: The aim of this study was to explore if specific hip and knee range-of-movement (ROM) tests can predict a risk factor for hamstring strain (HS) injury in male and female soccer players. Methods: One hundred amateur soccer players (56 men and 44 women) performed six tests to determine hip and knee ROM: straight leg raise test (SLR), modified Thomas test (TT), hip internal and external rotation (ER), hip abduction and adduction, Nachlas test and Ridge test. A logistic regression analysis was carried out to create a predictive model for HS injuries. Results: The percentage of HS injury was 20.45% and 30.35%, for female and male players. The logistic regression showed a significant model for both genders on the logit of suffering an HS injury with active-SLR and TT variables for females (R²_CS = 0.491; R²_N = 0.771) and active SLR and ER variables for males (R²_CS = 0.623; R²_N = 0.882). The predictive models correctly classify 95.5% and 94.6% of cases presenting good sensitivity (77.8% and 88.2%) and full (100%) and high (97.4%) specificity respectively. Furthermore, female players showed a greater ROM than males (p ≤ 0.01). Conclusion: Both female and male soccer players that suffered a HS injury had lower ROM in SLR, NT and RT and higher ROM in the TT that non-injured players. The tests that most likely predict HS injury are SLR and TT in females and SLR and ER in males. Thus, it is suggested to including specific exercises in amateur soccer players training programs to improve hip and knee ROM for injury prevention.

Poor Reporting of Exercise Interventions for Hamstring Strain Injury Rehabilitation: A Scoping Review of Reporting Quality and Content in Contemporary Applied Research

OBJECTIVE

To review the quality of reporting and identify the content of exercise interventions prescribed for hamstring strain injury (HSI) rehabilitation in the scientific literature from 2010 to 2020.

DESIGN

Scoping review.

LITERATURE SEARCH

We searched the bibliometric databases Web of Science, CINAHL, SPORTDiscus, Scopus, Cochrane Library, MEDLINE, and Embase.

STUDY SELECTION CRITERIA

Original research articles (randomized controlled trials and cohort studies) published from 2010 to 2020 that described an exercise rehabilitation intervention for participants with acute HSIs were included. Injuries must have been confirmed within 7 days of occurrence via clinical assessment and/or diagnostic imaging.

DATA SYNTHESIS

The quality of reporting, in terms of completeness of exercise intervention description, was evaluated using the Consensus on Exercise Reporting Template (CERT), and the content of interventions was categorized into exercise types.

RESULTS

Fourteen studies were included; exercise intervention quality of reporting was moderate in 3 studies and low in 11 studies. Using the 19-item CERT, an average of 8.8 items (range, 4-14) were reported across all studies. Two studies reported sufficient exercise content and progression information to allow replication. Exercises categorized as hamstring flexibility, hamstring strength, running related, and non-hamstring specific were prescribed in 13, 11, 10, and 10 studies, respectively. Half of the included studies incorporated all 4 exercise types in their exercise interventions.

CONCLUSION

There is a wide variety of exercise interventions applied in published research that has addressed HSI rehabilitation. Researchers must improve reporting quality to support other professionals in replicating exercise interventions and help practitioners to effectively implement research in practice. J Orthop Sports Phys Ther 2022;52(3):130-141. Epub 21 Sep 2021. doi:10.2519/jospt.2022.10641.

Hamstring injury patterns in professional male football (soccer): a systematic video analysis of 52 cases

OBJECTIVE

To closely describe the injury inciting events of acute hamstring injuries in professional male football (soccer) using systematic video analysis.

METHODS

Video footage from four seasons (2014-2019) of the two highest divisions in German male football was searched for moderate and severe (ie, time loss of >7 days) acute non-contact and indirect contact match hamstring injuries. Two raters independently categorised inciting events using a standardised procedure to determine specific injury patterns and kinematics.

RESULTS

52 cases of hamstring injuries were included for specific pattern analysis. The pattern analysis revealed 25 sprint-related (48%) and 27 stretch-related hamstring injuries (52%). All sprint-related hamstring injuries occured during linear acceleration or high-speed running. Stretch-related hamstring injuries were connected with closed chain movements like braking or stopping with a lunging or landing action and open chain movements like kicking. The kinematic analysis of stretch-related injuries revealed a change of movement involving knee flexion to knee extension and a knee angle of <45° at the assumed injury frame in all open and closed chain movements. Biceps femoris was the most affected muscle (79%) of all included cases.

CONCLUSION

Despite the variety of inciting events, rapid movements with high eccentric demands of the posterior thigh are likely the main hamstring injury mechanism. This study provides important data about how hamstring injuries occur in professional male football and supports the need for demand-specific multicomponent risk reduction programmes.

Strong, Fast, Fit, Lean, and Safe: A Positional Comparison of Physical and Physiological Qualities Within the 2020 Australian Women's Rugby League Team

ABSTRACT

Minahan, C, Newans, T, Quinn, K, Parsonage, J, Buxton, S, and Bellinger, P. Strong, Fast, Fit, Lean, and Safe: A positional comparison of physical and physiological qualities within the 2020 Australian Women's Rugby League team. J Strength Cond Res 35(12S): S11-S19, 2021-The purpose of the present study was to report the physical and physiological characteristics of elite women Rugby League (RL) players. Thirty-nine women (25.6 ± 4.3 years, 171.3 ± 7.7 cm, 83.5 ± 13.9 kg) from the 2020 Australian women's RL squad were recruited for this study. Players were categorized as adjustables (n = 7), backs (n = 15), or forwards (n = 17) for analysis. Each player was assessed for anthropometry, body composition (dual-energy X-ray absorptiometry), speed (5, 10 and 20 m sprint times), lower-body power (countermovement jump), upper-body power (medicine ball throw and explosive push up force), estimated one repetition maximum (e1RM) bench press, squat and bench pull, isometric mid-thigh pull strength, eccentric knee flexor strength, isometric hip abduction and adduction, and intermittent endurance performance (30-15 intermittent fitness test; 30-15 IFT). Linear mixed models were performed to compare positional groups. Forwards were significantly heavier and had greater fat mass, fat-free mass, and body fat percentage compared with backs and adjustables (P < 0.01). Backs were faster over 20 m compared with forwards (P = 0.025), whereas forwards had a lower 30-15 IFT peak velocity and estimated V̇o2peak compared with backs and adjustables. Nonetheless, when including body mass in the model, there were no differences between groups in 30-15 IFT peak velocity. There were no significant differences in other variables. These results provide contemporary benchmark physical, physiological, and anthropometric data for elite women RL players, which can inform recruitment, selection, training, and testing.

The Hamstrings: Anatomic and Physiologic Variations and Their Potential Relationships With Injury Risk

The incidence and recurrence of hamstrings injuries are very high in sports, posing elevated performance and financial-related costs. Attempts to identify the risk factors involved in predicting vulnerability to hamstrings injury is important for designing exercise-based programs that aim to mitigate the rate and severity of hamstrings injuries and improve rehabilitation strategies. However, research has shown that non-modifiable risk factors may play a greater role than modifiable risk factors. Recognizing non-modifiable risk factors and understanding their implications will afford the prescription of better suited exercise programs, i.e., that are more respectful of the individual characteristics. In a nutshell, non-modifiable risk factors can still be acted upon, even if indirectly. In this context, an underexplored topic is how intra and inter- individual anatomic and physiologic variations in hamstrings (e.g., muscle bellies, fiber types, tendon length, aponeurosis width, attachment sites, sex- and age-related differences) concur to alter hamstrings injuries risk. Some anatomic and physiologic variations may be modifiable through exercise interventions (e.g., cross-sectional area), while others may not (e.g., supernumerary muscle bellies). This apparent dichotomy may hide a greater complexity, i.e., there may be risk factors that are partially modifiable. Therefore, we explored the available information on the anatomic variations of the hamstrings, providing a deeper insight into the individual risk factors for hamstrings injuries and contributing with better knowledge and potential applications toward a more individualized exercise prescription.

Effects of Hip Flexion on Knee Extension and Flexion Isokinetic Angle-Specific Torques and HQ-Ratios

Background and Methods

During isokinetic knee strength testing, the knee flexion angles that correspond to the measured torque values are rarely considered. Additionally, the hip flexion angle during seated testing diverges from that in the majority of daily life and sporting activities. Limited information concerning the influence of hip angle, muscle contraction mode, and velocity on the isokinetic knee strength over the entire range of motion (ROM) is available.

Twenty recreational athletes (10 females, 10 males; 23.3 ± 3.2 years; 72.1 ± 16.5 kg; 1.78 ± 0.07 m) were tested for isokinetic knee flexion and extension at 10° and 90° hip flexion with the following conditions: (i) concentric at 60°/s, (ii) concentric at 180°/s, and (iii) eccentric at 60°/s. The effects of hip angle, contraction mode, and velocity on angle-specific torques and HQ-ratios as well as conventional parameters (peak torques, angles at peak torque, and HQ-ratios) were analyzed using statistical parametric mapping and parametric ANOVAs, respectively.

Results

Generally, the angle-specific and conventional torques and HQ-ratios were lower in the extended hip compared to a flexed hip joint. Thereby, in comparison to the knee extension, the torque values decreased to a greater extent during knee flexion but not consistent over the entire ROM. The torque values were greater at the lower velocity and eccentric mode, but the influence of the velocity and contraction mode were lower at shorter and greater muscle lengths, respectively.

Conclusions

Isokinetic knee strength is influenced by the hip flexion angle. Therefore, a seated position during testing and training is questionable, because the hip joint is rarely flexed at 90° during daily life and sporting activities. Maximum knee strength is lower in supine position, which should be considered for training and testing. The angle-specific effects cannot be mirrored by the conventional parameters. Therefore, angle-specific analyses are recommended to obtain supplemental information and consequently to improve knee strength testing.

Epidemiology of injuries in water board sports: trauma versus overuse injury

BACKGROUND

Surfing is an increasingly popular sport in the world, but it is not sufficiently investigated in terms of epidemiology of injuries and possible prevention strategies. Moreover, there are different surfing disciplines, with specific characteristics and therefore different potential risks of injury. The aim of this study was to look at the injuries of recreational surfers in an Italian cohort, distinguishing between trauma and overuse lesions and putting in evidence any difference between specific water board sports.

METHODS

The design is that of a retrospective observational study. An online survey was distributed to a group of Italian surfers that are members of a surfing association. The survey comprised: demographic data, surfing information such as number of sessions per year and years of experience, and surfing injuries story. The sample size consisted of 126 recreational surfers who practiced four different types of surfing: surf, kitesurf, windsurf and stand-up paddle.

RESULTS

The incidence of trauma was significantly higher than the incidence of overuse lesions in all four water board sports evaluated (e.g. in surf, 81% for trauma vs. 27% for overuse, with a difference of 55% , P<0.0001). There was a statistically significant effect of the number of surfing sessions per year both for trauma (W=6.36, P=0.0117) and for total injuries (trauma + overuse; W=4.30, P=0.0381), with a 12-times increased risk for the surfers who performed more than 80 sessions per year. The risk of overuse injuries was higher for those who practice surf for more than seven years (P=0.0193).

CONCLUSIONS

Traumas are more frequent than overuse injuries for all the investigated surfing disciplines. The risk of injury increases as the number of annual sessions and the years of practice increase, demonstrating that experience is not a protective factor, whereas higher exposure is certainly a risk factor. New injury prevention strategies should be based on athletic training and preparation programs, traditionally lacking among recreational surfers.

Time of Season and Game Segment Is Not Related to Likelihood of Lower-Limb Injuries: A Meta-Analysis

OBJECTIVE

Fatigue due to game play is often cited as a factor in musculoskeletal injuries; however, it is unclear whether or not this view is supported by published research findings. Given the importance researchers and practitioners place on the potential effects of game play with respect to injury, it is important to understand what inferences can be drawn from the collective research in this realm. This meta-analysis will consider the time of season and segment of the game, as it relates anterior cruciate ligament (ACL), groin, and hamstring injury occurrence.

DATA SOURCES

Database searches were run in PubMed, MEDLINE, SportDiscus, CINAHL, and Ausport, in addition to the inclusion of articles identified manually.

STUDY SELECTION

Search terms were chosen to identify articles related to each of the 3 injuries of interest. There were no date limitations placed on the articles, as such, all published articles listed in the databases up to November 2017 were eligible for selection if they met the search criteria.

DATA EXTRACTION

Initial searches yielded 1349 articles, and this was eventually reduced to 15 articles deemed suitable for inclusion in the meta-analysis, which provided 21 data sets.

DATA SYNTHESIS

Comparing the first half with the second half of the season, there were no differences in ACL, groin, or hamstring injury occurrences [ACL: odds ratio (OR), 1.27; confidence interval (CI), 0.43-3.78, groin: OR, 1.79; CI, 0.63-5.06, and hamstring: OR, 1.16; CI, 0.88-1.53]. Similarly, there were no differences in injury occurrence between the first and second halves of the game for the ACL or hamstring injuries (ACL: OR, 0.43; CI, 0.47-7.92, hamstring: OR, 0.85; CI, 0.58-1.24).

CONCLUSIONS

Findings from this meta-analysis determined that time in season or time in game does not influence risk of the ACL, groin, or hamstring injury. Commonly, many studies did not provide sufficient detail to be included in the meta-analysis. Consequently, it is recommended that future studies report data related to the timing of the injury within the season or game.

The uptake of the Nordic hamstring exercise programme as an injury prevention strategy in professional cricket in the United Kingdom and barriers to implementation

OBJECTIVES

To report hamstring prevention strategies of professional male cricket clubs in the United Kingdom, identify the application of the Nordic hamstring programme (NHP) and gain knowledge of medical teams' reasons for the NHP's inclusion or exclusion.

DESIGN

Cross-sectional questionnaire.

SETTING

Online survey.

PARTICIPANTS

15 (75%) of professional cricket clubs in the United Kingdom.

MAIN OUTCOME MEASURES

Survey based on the RE-AIM framework.

RESULTS

Twelve clubs reported having a formal hamstring injury prevention programme. The Nordic hamstring exercise and eccentric exercises (100%) were the most used interventions. Three clubs implemented the NHP, with one classed as fully compliant. Respondents partially agreed, on a 5 point Likert scale, that the Nordic hamstring exercise was effective at reducing injuries at their club (Mean 3.73 ± SD 0.70) and across professional cricket (3.87 ± 0.64). Barriers to implementation across cricket included players not positively perceiving the programme (60%) with a cultural change required (60%) for its adoption.

CONCLUSIONS

The Nordic hamstring exercise is positively received by medical personnel in professional cricket in conjunction with other prevention strategies. Three clubs have utilised the NHP in the last three seasons with one club considered fully compliant. A cultural shift from players and coaches may be required for successful NHP implementation.

The Role of Hip Joint Clearance Discrepancy as Other Clinical Predictor of Reinjury and Injury Severity in Hamstring Tears in Elite Athletes

Hamstring tear injuries (HTI) are the most prevalent injuries in athletes, with high reinjury rates. To prevent reinjury and reduce the severity of injuries, it is essential to identify potential risk factors. Hip characteristics are fundamental to optimal hamstring function. We sought to investigate the role of hip joint clearance discrepancy (JCD) as a risk factor for HTI and a clinical predictor of risk of reinjury and injury severity. A cross-sectional, retrospective study was performed with elite athletes (n = 100) who did (n = 50) and did not (n = 50) have a history of injury. X-rays were taken to assess JCD. We reviewed muscular lesions historial, and health records for the previous 5 years. Significant differences were found in injury severity (p = 0.026; ŋ²p = 0.105) and a number of injuries (p = 0.003; ŋ²p = 0.172). The multivariate analysis data indicated that JCD was significantly associated with the number of injuries and their severity (p < 0.05). In the stepwise regression model, JCD variability explained 60.1% of the number of injuries (R² 0.601) and 10.5% of injury severity (R² 0.0105). These results suggest that JCD could play an important role as a risk factor for HTI and also as a clinical predictor of reinjury and injury severity.

Implementing Strength Training Strategies for Injury Prevention in Soccer: Scientific Rationale and Methodological Recommendations

Due to the negative effects that injuries have on performance, club finances, and long-term player health (permanent disability after a severe injury), prevention strategies are an essential part of both sports medicine and performance. Purpose: To summarize the current evidence regarding strength training for injury prevention in soccer and to inform its evidence-based implementation in research and applied settings. Conclusions: The contemporary literature suggests that strength training, proposed as traditional resistance, eccentric, and flywheel training, may be a valid method to reduce injury risk in soccer players. Training strategies involving multiple components (eg, a combination of strength, balance, plyometrics) that include strength exercises are effective at reducing noncontact injuries in female soccer players. In addition, the body of research currently published supports the use of eccentric training in sports, which offers unique physiological responses compared with other resistance exercise modalities. It seems that the Nordic hamstring exercise, in particular, is a viable option for the reduction of hamstring injuries in soccer players. Moreover, flywheel training has specific training peculiarities and advantages that are related to the combination of both concentric and eccentric contraction, which may play an important role in injury prevention. It is the authors’ opinion that strength and conditioning coaches should integrate the strength training methods proposed here in their weekly training routine to reduce the likelihood of injuries in their players; however, further research is needed to verify the advantages and disadvantages of these training methods to injury prevention using specific cohorts of soccer players.

Eccentric Strength Assessment of Hamstring Muscles with New Technologies: a Systematic Review of Current Methods and Clinical Implications

BACKGROUND

Given the severe economic and performance implications of hamstring injuries, there are different attempts to identify their risk factors for subsequently developing injury prevention strategies to reduce the risk of these injuries. One of the strategies reported in the scientific literature is the application of interventions with eccentric exercises. To verify the effectiveness of these interventions, different eccentric strength measurements have been used with low-cost devices as alternatives to the widespread used isokinetic dynamometers and the technically limited handheld dynamometers. Therefore, the purpose of the present systematic review was to summarize the findings of the scientific literature related to the evaluation of eccentric strength of hamstring muscles with these new technologies.

METHODS

Systematic searches through the PubMed, Scopus, and Web of Science databases, from inception up to April 2020, were conducted for peer reviewed articles written in English, reporting eccentric strength of hamstrings assessed by devices, different to isokinetic and handheld dynamometers, in athletes.

RESULTS

Seventeen studies were finally included in the review with 4 different devices used and 18 parameters identified. The pooled sample consisted of 2893 participants (97% male and 3% female: 22 ± 4 years). The parameters most used were peak force (highest and average), peak torque (average and highest), and between-limb imbalance (left-to-right limb ratio). There is inconsistency regarding the association between eccentric hamstrings strength and both injury risk and athletic performance. There is no standardized definition or standardization of the calculation of the used parameters.

CONCLUSIONS

The current evidence is insufficient to recommend a practical guide for sports professionals to use these new technologies in their daily routine, due to the need for standardized definitions and calculations. Furthermore, more studies with female athletes are warranted. Despite these limitations, the eccentric strength of hamstring muscles assessed by different devices may be recommended for monitoring the neuromuscular status of athletes.

Hamstring muscle injury in the athlete: state of the art

Hamstring injuries (HSI) are the source of significant impairment and disability for both professional and recreational athletes. The incidence and prevalence of HSIs has been well documented in the literature, as they are among the most common soft tissue injuries reported. The significant time loss due to injury and the inherent risk of reinjury pose a significant issue to the athlete, their career longevity and the success of their respective team. This review will deal predominantly with describing the prevalence and incidence of HSI in athletes, discuss risk factors and the mechanisms of injury for HSI, how to properly diagnose, image and prognosticate appropriate return to sport (RTS) for individuals who have sustained an HSI, prescribe treatment and prevention strategies and to discuss relevant options to decrease overall risk of primary and secondary recurrence of HSI.Current treatments of acute HSI necessitate a thorough understanding of the mechanism of injury, identifying muscle imbalances and/or weakness, inclusion of eccentric and concentric hamstring (HS) and hip extension (HE) exercises, evaluation of pathokinematic movement patterns and use non-surgical methods to promote healing and RTS. This methodology can be used prospectively to mitigate the overall risk of HSI. Injection therapies for HSI, including ultrasound-guided platelet-rich plasma and corticosteroids, may impart some short-term benefit, but the existing literature is largely inconclusive with respect to long-term functional outcomes. Future directions should prioritise injury prevention, early diagnosis and targeted interventions that combine both non-surgical and minimally invasive orthobiological approaches and identifying biomechanical risk factors prospectively to mitigate risk.

Acute Hamstring Muscle Tears in Climbers-Current Rehabilitation Concepts

Acute hamstring injuries are often caused by the heel hook technique. This technique is unique to climbing and causes injury to muscular and inert tissues of the posterior thigh. The heel hook is used by climbers during strenuous ascent on overhanging walls and when crossing difficult terrain. The technique reduces the amount of upper body strength required during strenuous climbing because the climber's center of mass is retained within the base of support. The heel hook is stressful collectively for the hamstring muscle group and musculotendinous junction. Depending on injury severity, both conservative and surgical methods exist for the management of hamstring injuries. Contemporary approaches to rehabilitation primarily advocate the use of eccentric muscle strengthening strategies because of high rates of elongation stress associated with sprinting and team sports. However, there is reason to doubt whether this alone is sufficient to rehabilitate the climbing athlete in light of the high degree of concentric muscle strength required in the heel hook maneuver. This review examines the contemporary rehabilitation and strength and conditioning literature in relation to the management of acute hamstring musculotendinous injuries for the climbing athlete. The review provides a comprehensive approach for the rehabilitation and athletic preparation of the climbing athlete from the initial injury to full return to sports participation.

Potential prognostic factors for hamstring muscle injury in elite male soccer players: A prospective study

Hamstring injuries remain the most common injury type across many professional sports. Despite a variety of intervention strategies, its incidence in soccer players playing in the UEFA Champions League has increased by 4% per year over the last decade. Test batteries trying to identify potential risk factors have produced inconclusive results. The purpose of the current study was to prospectively record hamstring injuries, to investigate the incidence and characteristics of the injuries, and to identify possible risk factors in elite male soccer players, playing in the Kosovo national premier league. A total of 143 soccer players from 11 teams in Kosovo were recruited. To identify possible prevalent musculoskeletal or medical conditions a widespread health and fitness assessment was performed including isokinetic strength testing, Nordic hamstring strength test, functional tests, and a comprehensive anamnesis surveying previous hamstring injuries. On average 27.9% of the players sustained at least one hamstring injury with three players suffering bilateral strains with the re-injury rate being 23%. Injured players were significantly older and heavier and had a higher body mass index compared to non-injured ones (p < 0.05). There was a lower passing rate in the Nordic hamstring strength test and a higher injury incidence among the previously injured players compared to non-injured ones (p < 0.05). Except for hamstring/quadriceps ratio and relative torque at 60°/sec (p < 0.05) for dominant and non-dominant leg, there were no other significant differences in isokinetic strength regardless of the angular velocity. No differences were observed for functional tests between cohorts. Regression analysis revealed that age, Nordic hamstring strength test, previous injury history, and isokinetic concentric torque at 240°/sec could determine hamstring injuries by 25.9%, with no other significant predicting risk factors. The battery of laboratory and field-based tests performed during preseason to determine performance related skills showed limited diagnostic conclusiveness, making it difficult to detect players at risk for future hamstring injuries.

The prevalence of non-contact muscle injuries of the lower limb in professional soccer players who perform Salah regularly: a retrospective cohort study

Background

The present study assessed the prevalence of non-contact muscle injuries of the lower limbs, including hamstring injuries, in professional Russian soccer players who regularly perform Salah, an obligatory Muslim prayer performed 5 times a day.

Methods

Using a retrospective cohort study design, 68 professional male soccer players (excluding goalkeepers), 34 of whom were Muslims regularly performing Salah (exposure group) and 34 were randomly chosen non-Muslim players (control group), were included in the study. The groups were similar in their playing leagues, field positions, age (27 ± 3.1 vs 28 ± 4.2 years), and body mass index (22 ± 1.2 vs 23 ± 0.92 kg/m²).

Results

The incidence of hamstring injury was significantly lower in the exposure group (2 vs 14, p = 0.0085). A declining trend for the number of muscle injuries (either hamstring or not) was observed in the exposure group (11 vs 27, p = 0.0562). Two players in the exposure group and 11 in the control group (p = 0.0115, OR 0.1307, 95% CI 0.0276 to 0.5698) suffered a hamstring injury, with no statistically significant difference in the occurrence of other injuries. The total amount of the training and play days missed because of hamstring and other muscle injuries was significantly lower in the exposure group (24 vs 213 days, p = 0.0043, and 200 vs 344 days, p = 0.0066, respectively).

Conclusion

The prevalence of non-contact muscle injuries, including hamstring injuries, was lower in professional Russian soccer players who regularly performed Salah.

The relationship between physical fitness attributes and sports injury in female, team ball sport players: a systematic review

BACKGROUND

Understanding the relationships between physical fitness characteristics and sports injury may assist with the development of injury minimisation programs. The purpose of this systematic review was to investigate the association between physical fitness attributes and sports injury in female, team ball sport players.

METHODS

Four scientific databases (MEDLINE, EMBASE, SPORTDiscus, Scopus) and reference lists of relevant research were searched for eligible studies up to September 2, 2019. Full-text articles examining the relationship between physical fitness and sports injury in female, team ball sport players were included. A modified Downs and Black checklist was used to assess methodological quality. Data synthesis determined summary conclusions based on the number of significant relationships divided by the total relationships investigated and reported as a percentage. Level of certainty was identified for summary conclusions based on level of evidence. Sub-analyses regarding competition level, age, and single injury types were also conducted.

RESULTS

A total of 44 studies were included. Data synthesis revealed no associations (low to moderate certainty) between body composition (1/9; 11%), flexibility (18-20%), and balance (2/8; 25%) and 'any injury' classification. No associations (mostly of moderate certainty) were found between flexibility (0-27%), muscular strength (0-27%), and body composition (14-33%) and various body region injury classifications, whereas mixed summary conclusions were shown for balance (0-48%). Many associations between physical fitness and sports injury were deemed 'unknown' or with an insufficient level of certainty. Sub-analyses revealed no association between strength and noncontact ACL injuries (0/5; 0%) or ankle sprains (0/12; 0%), and between flexibility and ankle sprains (1/5; 20%); however, insufficient certainty of these results exists. Clear associations were concluded between balance and lower body injuries in female, non-elite (10/16; 63%) and junior (9/12; 75%) team ball sport players, with moderate and insufficient certainty of these results, respectively.

CONCLUSION

Limited evidence is available to demonstrate relationships between physical fitness and sports injury in female, team ball sport players. High-quality evidence investigating the multifactorial nature of sports injury, including the interactions physical fitness qualities have with other injury determinants, is needed to better understand the role of physical fitness in minimising sports injuries in female, team ball sport players.

TRIAL REGISTRATION

CRD42017077374 (PROSPERO on September 14, 2017).

Current concepts in the management of patellofemoral pain - The role of alignment

BACKGROUND

Patellofemoral pain is a prevalent and significant clinical problem that is often reported to persist even following evidence based intervention. It is clear therefore that there is much about this complex patient group that is not presently fully understood. This is particularly concerning given the reported links between patellofemoral pain in adolescence and the subsequent development of osteoarthritis and anxiety.

ASSESSMENT

Clinical assessment has historically focussed on biomechanical factors such as altered lower limb kinematics, muscle weakness and late muscle 'onset or activation' during activity. However when examined it is clear that study findings from patellofemoral populations are often inconsistent. Reasons for this are discussed and specifically the limitations around current 'gold standard' measurement methods, such as motion capture are outlined. A biomechanical approach is applied to demonstrate the importance of ensuring optimal patient alignment during rehabilitation, where optimal is defined as ensuring the most energy efficient muscle or muscles are used by the patient to perform a movement. This in turn ensures that the direction, magnitude and location of load applied to the skeleton during activity is optimal and therefore less likely to lead to injury.

TREATMENT

The role of alignment in patellofemoral pain and the importance of correcting this during rehabilitation is discussed, and examples provided. Validated, reliable, and reproducible methods of measuring skeletal geometry, muscle geometry, muscle force and direction, and kinematics of activity must be developed as a priority in order for us to further our understanding and improve outcomes in this complex clinical population.

Assessment of movement coordination strategies to inform health of movement and guide retraining interventions

INTRODUCTION

Exploring characteristics of human movement has long been the focus of clinicians and researchers. Changes in movement coordination strategies have been identified in the presence of pain highlighting the need for assessment in clinical practice. A major development in the understanding of movement related disorders is recognition of individual differences in presentation and consequently the need to tailor interventions based on assessment.

PURPOSE

The purpose of this masterclass is to build a rationale for the clinical assessment of movement coordination strategies, exploring loss of movement choices, coordination variability, and to present a clinical framework for individualised management, including the use of cognitive movement control tests and retraining interventions. An approach for the qualitative rating of movement coordination strategies is presented. A compromised movement system may be one characterised by a lack of ability to access motor abundance and display choice in the use of movement coordination strategies. The identification of lost movement choices revealed during the assessment of movement coordination strategies is proposed as a marker of movement health.

IMPLICATIONS FOR PRACTICE

The health of the movement system may be informed by the ability to display choice in movement coordination strategies. There is evidence that restoring these choices has clinical utility and an influence on pain and improved function. This approach seeks to provide individuals with more flexible problem solving, enabled through a movement system that is robust to each unique challenge of function. This assessment framework sits within a bigger clinical reasoning picture for sustained quality of life.

High-velocity elastic-band training improves hamstring muscle activation and strength in basketball players

BACKGROUND

The aim of this study was use surface EMG activity to assess changes in co-activation of knee flexors and extensors muscle groups during elastic-band exercise after 5 weeks of high-velocity elastic-band training in basketball players.

METHODS

College male basketball players (N.=18) were randomly divided into one of two groups: 1) the elastic-band training group performed low-load and high-velocity - lying prone - hamstring curls training three times per week; 2) the control group did not do any training. Pre- and post- training assessment included concentric knee extension and flexion at 60°/s and 240°/s, and the frequency of knee flexion and extension with elastic bands in the prone position. The EMG of the rectus femoris, semitendinosus muscles and the long head of the biceps femoris were assessed during these activities, and 30-m sprint running speed was measured from a stationary start and a running start.

RESULTS

It was shown that high-velocity elastic-band training was 1) feasible, 2) increased movement velocity and 3) muscle strength, 4) altered neural control such that excessive lengthening of the hamstring muscle, and hence strain-injuries, may be prevented and 5) improved sprint performance in basketball players.

CONCLUSIONS

These results suggest that high-velocity elastic-band training may be a tool to prevent hamstring strain-injuries in basketball players.

Sport injury prevention in-school and out-of-school? A qualitative investigation of the trans-contextual model

OBJECTIVE

To investigate junior secondary school students' experiences and perspectives of in-school and out-of-school sport-safety, with a particular focus on the meaning and content that they applied to the motivational and social cognitive factors of sport injury prevention.

DESIGN

Focus-group interview.

METHOD

Participants were 128 junior secondary school students (Form 1 to Form 3) aged between 12 and 16 years from two secondary schools. We organised focus-group interviews by class (group size = six to nine students). Seventeen groups completed semi-structured interviews regarding their experience, beliefs, and motives for injury prevention in-school and out-of-school. We analysed data by thematic content analysis using a typological approach.

RESULTS

Higher order themes (N = 7) including in-school and out-of-school motives and social cognitive factors and associated lower-order themes (N = 16), emerged from the analysis corresponding to constructs from trans-contextual model tenets.

CONCLUSIONS

The current study is the first qualitative study to explore junior secondary school students' experience and perspectives on sport injury prevention, using trans-contextual model as a framework for investigation. The findings contribute to a better understanding on their motivational and social cognitive factors in adopting sport injury prevention. The content of the theme behavior also indicated the inadequacy of students' knowledge of effective sport injury prevention techniques, and underscored the importance of sport safety education.

Hamstring rehabilitation in elite track and field athletes: applying the British Athletics Muscle Injury Classification in clinical practice

Rationale

Hamstring injuries are common in elite sports. Muscle injury classification systems aim to provide a framework for diagnosis. The British Athletics Muscle Injury Classification (BAMIC) describes an MRI classification system with clearly defined, anatomically focused classes based on the site of injury: (a) myofascial, (b) muscle–tendon junction or (c) intratendinous; and the extent of the injury, graded from 0 to 4. However, there are no clinical guidelines that link the specific diagnosis (as above) with a focused rehabilitation plan.

Objective

We present an overview of the general principles of, and rationale for, exercise-based hamstring injury rehabilitation in British Athletics. We describe how British Athletics clinicians use the BAMIC to help manage elite track and field athletes with hamstring injury. Within each class of injury, we discuss four topics: clinical presentation, healing physiology, how we prescribe and progress rehabilitation and how we make the shared decision to return to full training. We recommend a structured and targeted diagnostic and rehabilitation approach to improve outcomes after hamstring injury.

Specific interventions for prevention of muscle injury in lower limbs: systematic review and meta-analysis

Abstract Introduction: Muscle injuries show an incidence associated with extreme stretching, or even a high-intensity eccentric contraction. Such injuries cause severe damage to athletes, including lower performance, withdrawal, and psychological distress. In this scenario, the study of effective preventive methods is an indispensable factor in the routine of professional athletes, to reduce the incidence of injuries. Objective: To verify the effectiveness of three different interventions (warm-up, neuromuscular training, and eccentric exercise) to prevent muscle injuries in the lower limbs. Method: We searched the Cochrane Library, EMBASE, SPORTDiscus, PEDro, and PubMed databases from the earliest records until January 20, 2018. The search was performed from word combinations such as clinical trial, muscle strain, injury prevention. The data related to the outcome of prevention were grouped in meta-analysis and described in Risk Ratio (RR) with 95% confidence interval. Results: Sixteen studies were included: five assessed eccentric exercise, three investigated neuromuscular training, and eight observed warm-up. The eccentric exercise (RR = 3.49, 95% CI 2.36, 5.16, p < 0.00001) and the neuromuscular training (RR = 2.73, 95% CI 2.03, 2.68, p < 0.00001) showed significant effects on the prevention of muscle injuries in lower limbs. On the other hand, warm-up (RR = 1.57, 95% CI 0.92, 2.7, p = 0.10) was irrelevant in reducing the incidence of injuries in the body segment investigated. Conclusion: The outcomes presented provide clinical relevance inherent in the field practices, with intrinsic potential for practical application in the management of specific preventive techniques.