Hamstring Injury Risk Research Articles

Acute Changes in Hamstring Injury Risk Factors After a Session of High-Volume Maximal Sprinting Speed Efforts in Soccer Players.

Maximal sprinting speed (MSS) overexposure is associated with increased risk of injury. This study aimed to describe changes in sprint performance-related factors and hamstring strain injury (HSI) risk factors after a high-volume sprinting session in soccer players. A high-volume sprinting session can induce acute changes in several sprint performance-related factors (sprint time and mechanical properties) and HSI risk factors (posterior chain muscle strength, hamstring range of motion, and dynamic lumbo-pelvic control [LPC], measured as changes in anterior pelvic tilt [APT] during maximal speed sprinting). Prospective observational case series. Level 4. Fifteen active male amateur soccer players participated. Changes in sprint performance-related factors and HSI risk factors were examined for 72 hours after high-volume MSS efforts (H-VMSSE) using a soccer-contextualized multifactorial approach. Muscle damage proxy markers (hamstring perceived soreness and creatine kinase) were also examined. H-VMSSE induced decrements in sprint performance-related factors. Significant reductions in theoretical maximal horizontal velocity (P < 0.01; effect size [ES], -0.71) and performance (P = 0.02; ES, -0.59) were observed for 48 and 72 hours after H-VMSSE. Small but significant reductions in posterior chain muscle force-generating capacity were detected for 48 and 72 hours after H-VMSSE for the nondominant (P < 0.03; ES, -0.60) and dominant (P < 0.04; ES, -0.40) leg. Finally, players exhibited persistent small, albeit nonsignificant (P = 0.06; ES, 0.53), decreases in dynamic LPC (APT increases) for 72 hours after H-VMSSE. H-VMSSE induced declines in both sprint performance-related factors and HSI risk factors. Sprinting can alter a player's anatomic structure by increasing APT during the maximum speed phase of the sprint. A soccer-contextualized multifactorial approach might allow for the regulation of MSS dosage depending on individual HSI risk factor status, thereby serving as a tailored "vaccine" for sprinting needs.

Understanding How Eccentric Hamstring Strength Affects Football Performance: The Scientific Secret To Fast Running

This study aimed to investigate the impact of eccentric hamstring strength, identified as a significant factor in the risk of hamstring injury, on maximum sprinting speed. Twenty-three football players competing in the Turkish Super League, with an average age of 25.12±3.22, were included in the study. The eccentric hamstring muscle strength of the athletes was measured using the N3 Nordic Hamstring Curl Exercise device. The maximum sprinting speeds of the players were determined by a GPS analyst. It was found that there was no significant relationship between eccentric hamstring strength on both dominant and non-dominant sides and maximum sprinting speed. Similarly, no significant relationship was found between the difference in eccentric hamstring strength between the two sides and maximum sprinting speed values (p&gt;0.05). The study concluded that there is no association between eccentric hamstring muscle strength parameters and maximum sprinting speed in football players. As confirmed in this study, isolated maximum eccentric hamstring muscle strength alone does not appear to be the sole determinant parameter for horizontal force production during sprinting. However, further research is needed in this area.

The Fragility Index of Risk Factors for Hamstring Injuries.

OBJECTIVE: To determine the Fragility Index of hamstring injury risk factors, defined as the minimum number of participants who would need to change classification to make a hamstring injury risk factor statistically nonsignificant. DESIGN: Retrospective secondary data analysis. METHODS: Studies that investigated 1 or more risk factors for hamstring injury, and presented sufficient data to develop a 2 × 2 contingency table were included. A systematic literature search and reference screening of a recent hamstring injury systematic review were conducted to identify 78 articles. Relative risk and 95% confidence intervals were determined and then systematically recalculated by removing 1 observation from the high-risk injury count and adding it to the high-risk noninjury count. The Fragility Index for a risk factor was the number of observations required to be moved between groups until the relative risk was no longer significant. RESULTS: The median Fragility Index of all hamstring injury risk factors was 3 (Q1-Q3 = 2-6). The Fragility Index for nonmodifiable risk factors was 3 (Q1-Q3 = 2-6) and 3 (Q1-Q3 = 2-5) for modifiable risk factors. Over 35% of all included hamstring injury risk factors had a Fragility Index of ≤2. CONCLUSION: Most statistically significant hamstring injury risk factors are fragile associations. The interpretation of significant hamstring injury risk factors should consider a range of statistical metrics, and while the Fragility Index should never be considered in isolation, it is an intuitive measure to help assess the robustness of findings. J Orthop Sports Phys Ther 2024;54(10):672-678. Epub 4 September 2024. doi:10.2519/jospt.2024.12300.

The 11+ injury prevention programme decreases rate of hamstring strain injuries in male collegiate soccer players

ObjectivesTo investigate if the 11+ injury prevention programme decreases the risk of hamstring injury and improves recovery time and determine whether compliance with the 11+ affects hamstring injury risk.MethodsThis study...

Hamstrings on focus: Are 72 hours sufficient for recovery after a football (soccer) match? A multidisciplinary approach based on hamstring injury risk factors and histology

ABSTRACT This study aimed to assess acute and residual changes in sprint-related hamstring injury (HSI) risk factors after a football (soccer) match, focusing on recovery within the commonly observed 72-h timeframe between elite football matches. We used a multifactorial approach within a football context, incorporating optical and ultrastructural microscopic analysis of BFlh (biceps femoris long head) muscle fibres, along with an examination of BFlh fibre composition. Changes in sprint performance-related factors and HSI modifiable risk factors were examined until 3 days after the match (MD +3) in 20 football players. BFlh biopsy specimens were obtained before and at MD +3 in 10 players. The findings indicated that at MD +3, sprint-related performance and HSI risk factors had not fully recovered, with notable increases in localized BFlh fibre disruptions. Interestingly, match load (both external and internal) did not correlate with changes in sprint performance or HSI risk factors nor with BFlh fibre disruption. Furthermore, our study revealed a balanced distribution of ATPase-based fibre types in BFlh, with type-II fibres associated with sprint performance. Overall, the results suggest that a 72-h recovery period may not be adequate for hamstring muscles in terms of both HSI risk factors and BFlh fibre structure following a football match.

Does Short-Term Speed Endurance Soccer Training Improve Physical Performance?

Objectives. This study is aimed at analyzing the impact of short-term Speed Endurance Soccer Training (SEST) training on the physical performance of young soccer players. Materials and methods. The true experiment method was used in this study. The study population comprised a total of 122 individuals. Furthermore, by using random sampling techniques, a sample of 30 persons was selected with an average age of 15.2 ± 0.81 years, height 168.1 ± 4.82 cm, weight 57.85 ± 11.93 kg, and BMI 20.34 ± 3.37. Physical performance instruments included the Running Based Anaerobic Sprint Test (RAST), Yo-Yo intermittent test level 1, 20-meter sprint, and standing broad jump test. The study used the paired t-test to evaluate the effect of each group and the independent samples t-test to compare the improvement in the experimental (SEST) and control groups. Statistical significance was set at p &lt; 0.05. Results. The paired t-test showed significant differences between the pretest and post-test in the SEST group in anaerobic (p = .000, Δ% = 8.4), aerobic (p = .000, Δ% = 7.48), and speed (p = .000, Δ% = 3.39) capacities. Meanwhile, there were no considerable differences in the variables for the control group. According to the independent t-test results, a significant difference in effect between the SEST group and the CTRL group was revealed. The SEST group demonstrated marked differences in anaerobic, aerobic and speed variables with a p-value = 0.000. Conclusions. The study reveals that short-term Speed Endurance Soccer Training contributes to enhancing the physical performance of soccer players. However, caution should be exercised regarding the potential risk of hamstring injury in individuals with unprepared muscles.

Differences in Injury Profiles Between Female and Male Athletes Across the Participant Classification Framework: A Systematic Review and Meta-Analysis.

Female sex is a significant determinant of anterior cruciate ligament (ACL) injury. It is not understood if sex is a key determinant of other sports-related injuries. The aim of this systematic review was to identify where differences in injury profiles are most apparent between the sexes in all sports across the six-tiered participant classification framework. This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and the 'implementing PRISMA in Exercise, Rehabilitation, Sport medicine and SporTs science'(PERSiST) guidance. The databases PubMed, CINAHL, Web of Science, SPORTDiscus, Medline, Scopus, Cochrane Library and EBSCO were searched from database inception to 24 April 2023. Longitudinal, prospective and retrospective cohort studies and cross-sectional and descriptive epidemiology studies that used standard injury data collection were included. Studies were excluded if injuries were not medically diagnosed and if injuries were not reported and/or analysed by sex. Two reviewers independently extracted data and assessed study quality using the Downs and Black checklist. Overall, 180 studies were included (8 tier-5, 40 tier-4, 98 tier-3, 30 tier-2, 5 tier-1 studies; one study included data in two tiers). Of those, 174 studies were of moderate quality and six studies were of limited quality. In sex-comparable sports, there was moderate evidence that female athletes had greater risk of knee injury (relative risk (RR) 2.7; 95% CI 1.4-5.5), foot/ankle injuries (RR 1.25; 95% CI 1.17-1.34), bone stress injury (RR 3.4; 95% CI 2.1-5.4) and concussion (RR 8.46; 95%CI 1.04-68.77) than male athletes. Male athletes were at increased risk of hip/groin injuries (RR 2.26; 95% CI 1.31-3.88) and hamstring injuries (RR 2.4; 95% CI 1.8-3.2) compared with females, particularly in dynamic sports. Male athletes were 1.8 (1.37-2.7) to 2.8 (2.45-3.24) times more likely to sustain acute fractures than female athletes, with the highest risk in competition. Most studies in all cohorts were of moderate quality (mean/range of scores tier-5: 17 ± 2.2 [14-20], tier-4: 16.9 ± 1.9 [11-21], tier-3: 16.9 ± 1.5 [11-20], tier-2: 16.3 ± 2.2 [11-20], tier-1 studies: 15.6 ± 1.3 [14-17] out of 28 on the Downs and Black checklist), with only six studies of limited quality. Female athletes' propensity for bone stress injuries highlights opportunities to reinforce development of optimal bone health during adolescence and to outline the effects of energy availability. Earlier strength development and exposure to neuromuscular training programmes and modification of skill development in female athletes may be effective strategies for reducing lower limb injury risk. Key components of neuromuscular training programmes could be beneficial for reducing hip/groin and hamstring injury risk in male athletes. There may be a need for sex-specific prevention and return-to-sport protocols for sports-related concussion in female athletes. Female sex was a key determinant of sports-related injuries beyond ACL injury including foot/ankle injury, bone stress injury and sports-related concussion. Male sex was a key determinant of hip/groin, hamstring injury and upper limb injury. PROSPERO registration number: CRD42017058806 (last updated on 7th June 2023).

Hamstring and knee injuries are associated with isometric hip and trunk muscle strength in elite Australian Rules and Rugby League players

ObjectivesThis study investigated relationships between isometric trunk and hip extensor strength, lumbar muscle morphology, and the risk of hamstring and knee ligament injuries in Australian Football League and National Rugby League players. DesignProspective cohort study. MethodsTrunk and hip extensor strength, multifidus and quadratus lumborum cross-sectional area were measured during the 2020 pre-season. Logistic regressions and decision trees were employed to explore associations between maximum strength, strength endurance, multifidus and quadratus lumborum cross-sectional area, age, previous injuries, and hamstring and knee ligament injury risk. ResultsGreater strength endurance [odds ratio = 0.42 (0.23–0.74), p = 0.004] and maximum strength [odds ratio = 0.55 (0.31–0.94), p = 0.039] reduced hamstring injury risk. Increased risk of knee ligament injuries was associated with larger multifidus [odds ratio = 1.66 (1.14–2.45), p = 0.008] and higher multifidus to quadratus lumborum ratio (odds ratio = 1.57 (1.13–2.23), p = 0.008]. Decision tree models indicated that low strength endurance (< 99 Nm) characterised hamstring strains, while high (≥ 1.33) multifidus to quadratus lumborum ratio mitigated risk. Knee ligament injuries were associated with larger (≥ 8.49 cm2) multifidus, greater (≥ 1.25) multifidus to quadratus lumborum ratio, and lower maximum strength (< 9.24 N/kg). ConclusionsPlayers with lower trunk and hip extensor maximum strength and strength endurance had increased risk of hamstring injuries, while knee ligament injury risk was elevated with larger multifidus cross-sectional area, higher multifidus to quadratus lumborum ratio, and lower maximum trunk and hip extensor strength.

A Conceptual Exploration of Hamstring Muscle-Tendon Functioning during the Late-Swing Phase of Sprinting: The Importance of Evidence-Based Hamstring Training Frameworks.

An eccentrically lengthening, energy-absorbing, brake-driven model of hamstring function during the late-swing phase of sprinting has been widely touted within the existing literature. In contrast, an isometrically contracting, spring-driven model of hamstring function has recently been proposed. This theory has gained substantial traction within the applied sporting world, influencing understandings of hamstring function while sprinting, as well as the development and adoption of certain types of hamstring-specific exercises. Across the animal kingdom, both spring- and motor-driven muscle-tendon unit (MTU) functioning are frequently observed, with both models of locomotive functioning commonly utilising some degree of active muscle lengthening to draw upon force enhancement mechanisms. However, a method to accurately assess hamstring muscle-tendon functioning when sprinting does not exist. Accordingly, the aims of this review article are three-fold: (1) to comprehensively explore current terminology, theories and models surrounding muscle-tendon functioning during locomotion, (2) to relate these models to potential hamstring function when sprinting by examining a variety of hamstring-specific research and (3) to highlight the importance of developing and utilising evidence-based frameworks to guide hamstring training in athletes required to sprint. Due to the intensity of movement, large musculotendinous stretches and high mechanical loads experienced in the hamstrings when sprinting, it is anticipated that the hamstring MTUs adopt a model of functioning that has some reliance upon active muscle lengthening and muscle actuators during this particular task. However, each individual hamstring MTU is expected to adopt various combinations of spring-, brake- and motor-driven functioning when sprinting, in accordance with their architectural arrangement and activation patterns. Muscle function is intricate and dependent upon complex interactions between musculoskeletal kinematics and kinetics, muscle activation patterns and the neuromechanical regulation of tensions and stiffness, and loads applied by the environment, among other important variables. Accordingly, hamstring function when sprinting is anticipated to be unique to this particular activity. It is therefore proposed that the adoption of hamstring-specific exercises should not be founded on unvalidated claims of replicating hamstring function when sprinting, as has been suggested in the literature. Adaptive benefits may potentially be derived from a range of hamstring-specific exercises that vary in the stimuli they provide. Therefore, a more rigorous approach is to select hamstring-specific exercises based on thoroughly constructed evidence-based frameworks surrounding the specific stimulus provided by the exercise, the accompanying adaptations elicited by the exercise, and the effects of these adaptations on hamstring functioning and injury risk mitigation when sprinting.

Most modifiable risk factors for hamstring muscle injury in women’s elite football are extrinsic and associated with the club, the team, and the coaching staff and not the players themselves: the UEFA Women’s Elite Club Injury Study

PurposeTo describe the perceived importance of suggested hamstring injury risk factors according to chief medical officers (CMOs) of European women’s professional football clubs. A secondary objective was to compare if these perceptions differed between teams with a lower-than-average and higher-than-average hamstring injury burden.MethodsThe CMOs of eleven European professional women’s football clubs were initially asked to suggest modifiable risk factors for hamstring injury. These risk factors were rated in according with their perceived importance on a 5-graded Likert scale. Participating teams were divided in two groups depending on their hamstring injury burden during the 2020/21 season. The LOW group consisted of six teams that had a lower-than-average hamstring injury burden. The HIGH group consisted of five teams that had a higher-than-average hamstring injury burden.ResultsTwenty-one risk factors were suggested, most of which were extrinsic in nature, hence associated with the coaching staff, the team or the club organization rather than with the players themselves. The risk factors with the highest average importance were: “lack of communication between medical staff and coaching staff” and “load on players” (each with a weighted average of 3.9), followed by “lack of regular exposure to high-speed football actions during training” and “playing matches 2–3 times a week” (weighted average of 3.8 and 3.7). Differently from the LOW group, the HIGH group perceived the coaching factors (style of coach leadership, training/exercise surveillance by coaching staff) as more important.ConclusionIn accordance to the eleven CMOs recruited in this study, most risk factors for hamstring injuries are extrinsic in nature and associated with the club, the team, and the coaching staff, and not the players themselves.Level of evidenceLevel III.

Differences in Peak Knee Flexor Force between Eccentric-Only and Combined Eccentric-Concentric Nordic Hamstring Exercise.

In many sports, the hamstring strain injury is a common injury. There is evidence that the Nordic hamstring exercise (NHE), a knee flexor exercise, can reduce hamstring injury risk in athletes. In research on hamstring injury prevention, eccentric-only NHE is typically performed, whereas in sports, it is relatively common for athletes to perform NHE eccentrically-concentrically. Further, NHE strength is generally assessed by measuring knee flexor force through an ankle brace, attached atop of a load cell. An alternative method might be to assess knee flexor force about the knee joint using a force plate. The aim of the study was to investigate differences in peak knee flexor force between eccentric-only and combined eccentric-concentric NHE. The purpose was also to determine the correlation between hamstring force measured at the ankle using a load cell (current gold standard) and force assessed about the knee joint using a force plate during NHE. Fifteen junior and senior elite soccer and track and field athletes (3 women and 12 men aged 17-27 years) performed eccentric NHE (ENHE) in which they leaned forward as far as possible until breakpoint and eccentric-concentric NHE (ECNHE) where they returned to the starting position. A linear encoder measured the position at which peak force occurred during the NHEs. Force assessed at the ankle differed significantly (678 vs. 600 N, p < 0.05), whereas force about the knee joint did not (640 vs. 607 N, p > 0.05) between ENHE and ECNHE (12 and 5% difference, respectively). The forward distance achieved by the participants in cm at breakpoint for ENHE was 37% higher than at the coupling phase for ECNHE (74 vs. 54 cm, p < 0.001). Very strong significant (p < 0.01) correlations were noted between peak force assessed at the ankle and about the knee joint for ENHE and ECNHE, r = 0.96 and r = 0.99, respectively. Our results suggest that ECNHE, where peak knee flexor force was reached with 37% less forward movement, may complement ENHE, i.e., during hamstring injury rehabilitation, where a position of great knee extension may not be well tolerated by the athlete. Further, assessing knee flexor force about the knee joint using a force plate may provide an alternative to measuring force at the ankle using a load cell when testing NHE strength.

Risk factors for hamstring muscle injury in male elite football: medical expert experience and conclusions from 15 European Champions League clubs

ObjectivesTo describe the perceived importance of suggested hamstring injury risk factors according to chief medical officers (CMOs) of European male professional football clubs. A secondary objective was to compare if...

Game-play affects hamstring but not adductor muscle fiber mechanics in elite U20 basketball athletes

Introduction: Game-play towards the latter part of a half or game is thought to induce ‘muscle fatigue’ which has been associated with increased risk of hamstring and hip adductor muscle tendon unit (MTU) injury. Effects of game-play are typically investigated using fixed-intensity laboratory protocols, which may be erroneous as game-play is self-paced and effects of fatigue are task dependent. There is a need to understand how actual game-play might affect muscle function, and thus performance and MTU injury risk in sport.

The FIFA 11+ injury prevention program reduces the incidence of hamstring injury among soccer players: a systematic review and meta-analysis

Introduction: Hamstring injury are among the most common non-contact injuries in sports. In soccer, which is the most popular sport worldwide, hamstring injuries represent between 15 and 50 % of all muscle injuries. Sports injury prevention programs have been showing promising results in reducing the risk of hamstring injury. The purpose of this systematic review and meta-analysis was to investigate the effectiveness of the FIFA 11+ Injury Prevention Program on reducing the incidence hamstring injury among soccer players. Methods: This systematic review with meta-analysis was based upon the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). A systematic search for relevant studies published from 1985-2022 using the following databases: Cochrane Library, MEDLINE, AMED, PubMed, Web of Science, and PEDro was conducted. The keywords used in the search strategy were ‘neuromuscular training’, ‘injury prevention programs’, ‘FIFA 11+’, ‘hamstring injury’, ‘soccer, and variations of these search terms. Included studies had to be randomized controlled trials using FIFA 11+ Injury Prevention Program for soccer players with the primary outcome being hamstring injury rate. There were no restrictions of age or playing level. The random-effects model was used in analysing the extracted data by the RevMan Meta-Analysis software version 5. Results: The pooled results of 2949 players and 274032 exposure hours showed 66% hamstring injury reduction per 1000 hours of exposure in the intervention group compared to control group with an injury risk ratio [IRR] of 0.34 (95% confidence interval [CI] 0.21–0.55, P < 0.0001). Discussion/Conclusion: This is the first meta-analysis of randomized controlled trials to evaluate the effectiveness of FIFA 11+ Injury Prevention Program in reducing the incidence of hamstring injury among soccer players. This meta-analysis demonstrates that the FIFA 11+ Injury Prevention Program reduces the incidence of hamstring injury by 66% among soccer players. Impact/Application to the field: The results showed a 66 % hamstring injury reduction. Therefore, it's recommended that soccer players and coaches implement the FIFA 11+ Injury Prevention Program in their current practice. Conflict of interest statement: No conflict of interest of relevance to the submission of this abstract.

The Effects of Training Interventions on Modifiable Hamstring Strain Injury Risk Factors in Healthy Soccer Players: A Systematic Review

ABSTRACT Despite promising research on various soccer-specific injury prevention programs, hamstring strain injuries (HSIs) persist in being a major problem in the sport. Therefore, in an attempt to expand the current knowledge on the prevention of HSIs, this systematic review aimed to identify how modifiable risk factors for HSIs (hamstring strength, hamstring:quadriceps [H:Q] strength ratios, biceps femoris long head fascicle length, and hamstring angle of peak torque) were altered following various training interventions. The protocol was preregistered on PROSPERO (CRD42020177363). The literature search was conducted on PubMed, SportDISCUS, and Web of Science. Following the search process, 20 studies were included in the systematic review, and the methodological quality of these studies was reported. Interventions were categorized based on exercise characteristics (movement velocity and contraction type), and the effects of each intervention subgroup were analyzed separately for all proposed risk factors for HSIs. Our findings show that a broad variety of exercise types (i.e., high- and low-velocity movements, eccentric only and traditional exercises) improves all risk factors for HSIs compared with fewer exercise types. Therefore, these findings suggest that hamstring injury risk factors can best be modified using a wide variety of exercises compared with, for example, only 1 or 2 specific exercises.

Prevention of Hamstring Injuries in Male Soccer Athletes

Abstract Background: One of the most frequently injured muscle groups in soccer is the hamstring group. Soccer players have high rates of hamstring injury (HSI) due to frequent sprinting, changes in direction and similar high-risk activities. Such movements put immense stress on the hamstrings which can lead to injury. Over the last decade, at least four different HSI prevention programs and techniques have been explored in research. The purpose of this review is to assess the effectiveness of these methods. Methods: Studies in this review were collected using multiple database searches of PubMed. A total of six studies were selected, all either randomized controlled trials (RCTs) or cluster-RCTs. The selected trials were from various soccer leagues in Denmark, Japan, the Netherlands, and the United States. Results: The most prevalently studied method is the Nordic hamstring exercise (NHE). Studies that utilized the NHE, either as a stand-alone or within a program, reduced the risk of HSI by 15-71%. In addition, effective programs were characterized by progressively increasing the difficulty of exercises and high compliance rates. Conclusion: Studies that utilized the NHE showed effectiveness in the prevention of hamstring injuries in male soccer athletes. Based on the limited research available, it is unclear whether adding other exercises to prevention programs further reduces injury risk. More research is needed to explore new and existing prevention methods in a variety of populations and regions.

Prevention of Hamstring Injuries in Male Soccer Athletes

Abstract Background: One of the most frequently injured muscle groups in soccer is the hamstring group. Soccer players have high rates of hamstring injury (HSI) due to frequent sprinting, changes in direction and similar high-risk activities. Such movements put immense stress on the hamstrings which can lead to injury. Over the last decade, at least four different HSI prevention programs and techniques have been explored in research. The purpose of this review is to assess the effectiveness of these methods. Methods: Studies in this review were collected using multiple database searches of PubMed. A total of six studies were selected, all either randomized controlled trials (RCTs) or cluster-RCTs. The selected trials were from various soccer leagues in Denmark, Japan, the Netherlands, and the United States. Results: The most prevalently studied method is the Nordic hamstring exercise (NHE). Studies that utilized the NHE, either as a stand-alone or within a program, reduced the risk of HSI by 15-71%. In addition, effective programs were characterized by progressively increasing the difficulty of exercises and high compliance rates. Conclusion: Studies that utilized the NHE showed effectiveness in the prevention of hamstring injuries in male soccer athletes. Based on the limited research available, it is unclear whether adding other exercises to prevention programs further reduces injury risk. More research is needed to explore new and existing prevention methods in a variety of populations and regions.

Is Workload Associated With Hamstring and Calf Strains in Professional Baseball Players? An Analysis of Days of Rest, Innings Fielded, and Plate Appearances.

The influence of player workload on hamstring and calf injuries in professional baseball players remains unknown. Increased workload would significantly increase hamstring and calf strain injury risk. Case-control. Level 3. All professional baseball players who sustained a hamstring or calf injury between 2011 and 2017 were identified using the Major League Baseball (MLB) Health and Injury Tracking System (HITS). A separate player usage dataset was used to determine workload. We then compared these variables between player games 2, 6, 12, and >12 weeks before a documented calf strain to player games from a noncalf injury control group. In a paired analysis, we compared the acute workload (2, 6, and 12 weeks) before injury with the injured player's workload >12 weeks before injury. There were 175 unique calf strains (71% occurred in position players) and 1042 unique hamstring strains (97.8% occurred in position players) documented in the MLB HITS database from 2011 to 2017. In all time periods, position players with fewer days rest, more innings fielded, and more plate appearances were associated with a higher risk of subsequent hamstring and calf strains. Having only 1 day rest was associated with a 2.08-fold increase in percentage of players who sustained a subsequent calf strain compared with those with 4 days rest. Position players with >5 days of rest had a 4.03-fold decrease in percentage of players who sustained a hamstring strain compared with players with 1 day rest. Position players who fielded >9 innings per game had a 2.01-fold increase in percentage of players with a subsequent calf strain and a 3.68-fold increase in percentage of players who sustained a subsequent hamstring strain compared with players who only fielded 1 innings per game. Position players with fewer days rest, more innings fielded, and more plate appearance per game had an increased risk of sustaining a hamstring or calf injury. Increased workload had a direct relationship with risk of hamstring and calf strains in professional baseball players. Teams should consider more days rest for position players to avoid calf injuries.

Evidence-Based Hamstring Injury Prevention and Risk Factor Management: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Background: Hamstring injuries are common among athletes. Considering the potentially prolonged recovery and high rate of recurrence, effective methods of prevention and risk factor management are of great interest to athletes, trainers, coaches, and therapists, with substantial competitive and financial implications. Purpose: To systematically review the literature concerning evidence-based hamstring training and quantitatively assess the effectiveness of training programs in (1) reducing injury incidence and (2) managing injury risk factors. Study Design: Systematic review and meta-analysis; Level of evidence, 1. Methods: A computerized search of MEDLINE, CINAHL, Cochrane Central Register of Controlled Trials, and SPORTDiscus with manual screening of selected reference lists was performed in October 2020. Randomized controlled trials investigating methods of hamstring injury prevention and risk factor management in recreational, semiprofessional, and professional adult athletes were included. Results: Of 2602 articles identified, 108 were included. Eccentric training reduced the incidence of hamstring injury by 56.8% to 70.0%. Concentric hamstring strength increased with eccentric (mean difference [MD], 14.29 N·m; 95% CI, 8.53-20.05 N·m), concentric, blood flow–restricted, whole-body vibration, heavy back squat, FIFA 11+ (Fédération Internationale de Football Association), and plyometric training methods, whereas eccentric strength benefited from eccentric (MD, 26.94 N·m; 95% CI, 15.59-38.30 N·m), concentric, and plyometric training. Static stretching produced greater flexibility gains (MD, 10.89°; 95% CI, 8.92°-12.86°) than proprioceptive neuromuscular facilitation (MD, 9.73°; 95% CI, 6.53°-12.93°) and dynamic stretching (MD, 6.25°; 95% CI, 2.84°-9.66°), although the effects of static techniques were more transient. Fascicle length increased with eccentric (MD, 0.90 cm; 95% CI, 0.53-1.27 cm) and sprint training and decreased with concentric training. Although the conventional hamstring/quadriceps (H/Q) ratio was unchanged (MD, 0.03; 95% CI, –0.01 to 0.06), the functional H/Q ratio significantly improved with eccentric training (MD, 0.10; 95% CI, 0.03-0.16). In addition, eccentric training reduced limb strength asymmetry, while H/Q ratio and flexibility imbalances were normalized via resistance training and static stretching. Conclusion: Several strategies exist to prevent hamstring injury and address known risk factors. Eccentric strengthening reduces injury incidence and improves hamstring strength, fascicle length, H/Q ratio, and limb asymmetry, while stretching-based interventions can be implemented to improve flexibility. These results provide valuable insights to athletes, trainers, coaches, and therapists seeking to optimize hamstring training and prevent injury.

Hamstring injuries in England and Wales elite men's domestic cricket from 2010 to 2019

ObjectivesDescribe hamstring injury incidence across competition formats, activity at time of injury, and time of season, facilitating the identification of injury risk factors in elite men's senior First-Class County Cricket. DesignProspective cohort. MethodsHamstring time loss injury incidence (between format, activity, and time of season) calculated for elite men's senior First-Class County Cricket seasons 2010 to 2019. ResultsThe diagnosis with the highest seasonal incidence was ‘Biceps femoris strain grade 1–2’ (2.5 injuries/100 players). Hamstring injury incidence was highest in One-Day cricket (mean 27.2 injuries/1000 team days). Running between wickets when batting was the activity associated with the highest incidence in the shorter competition formats (8.4 and 4.8 injuries/1000 team days for One-Day and T20, respectively). Bowling delivery stride or follow through was the activity with the highest incidence for longer multi-day Test format (mean 2.3 injuries/1000 team days), although similar incidence was observed across all formats for this activity. Most injuries were sustained at the start of the season (April; 22.7 injuries/1000 team days), with significantly fewer injuries at end of the season (September; 4.1 injuries/1000 team days). ConclusionsSimilar bowling injury incidence across formats suggests hamstring injury risk is associated more with the activity itself, whereas injury risk when batting was susceptible to changes in match intensity. The notably higher (albeit non-significant) incidence in April may allude to a lack of preparedness to meet the physical demands of the start of the season. The findings have practical relevance for practitioners, identifying potential opportunities for preventative strategies.