Rehabilitation and return to sport after hamstring strain injury

Conservative management of proximal hamstring avulsion: A clinical study

Introduction

The management of proximal hamstring tear (PHT) is debated and consensus regarding recommended measures and individual treatment regimens is lacking. The present investigation evaluated the efficacy of a conservative management of partial and complete PHT.

Methods

The present observational study was conducted following the STROBE statement. In June 2018 the medical databases of the BG Klinikum Bergmannstrost Halle, Germany were accessed. All the patients with PHT were retrieved. The outcomes of interest were to evaluate the clinical examination, PROMs, imaging, and isokinetic muscle strength at the baseline and last follow-up.

Results

31 patients were enrolled in the present study. Nine patients (29 % (9 of 31) described local pain at the ischial tuberosity in sitting situations and also in manual palpation. A persistent gap in the tendon string beneath the tuberosity in manual palpation was reported in 25.8 % (8 of 31). The mean VAS at the last follow-up was 2.3 ± 2.3. The mean LEFS score was 50.9 ± 18.8.Control MRI at follow-up showed scarring restitution in the proximal tendon in all patients in the partial tear group. In the complete tear group, a persisting defect state of the proximal tendon course was found in 45 % (9 of 20). The injured side achieved 81.5 ± 22.2 % of the force of the uninjured side, measured in the flexion movement at 60°/s. At an angular velocity of 240°/s, 83.2 ± 26.3 % of the force of the uninjured side was achieved.

Conclusion

According to the main findings of the present study, conservative therapy of PTH tears is associated with good clinical outcomes. High-quality investigations are required to establish the proper therapeutic algorithm and advantages of conservative management compared to a surgical approach.

Level of evidence

Level III.

Hamstring Injuries, From the Clinic to the Field: A Narrative Review Discussing Exercise Transfer

PURPOSE

The optimal approach to hamstring training is heavily debated. Eccentric exercises reduce injury risk; however, it is argued that these exercises transfer poorly to improved hamstring function during sprinting. Some argue that other exercises, such as isometric exercises, result in better transfer to running gait and should be used when training to improve performance and reduce injury risk. Given the performance requirements of the hamstrings during the terminal swing phase, where they are exposed to high strain, exercises should aim to improve the torque production during this phase. This should improve the hamstrings' ability to resist overlengthening consequently, improving performance and limiting strain injury. Most hamstring training studies fail to assess running kinematics postintervention. Of the limited evidence available, only eccentric exercises demonstrate changes in swing-phase kinematics following training. Studies of other exercise modalities investigate effects on markers of performance and injury risk but do not investigate changes in running kinematics.

CONCLUSIONS

Despite being inconsistent with principles of transfer, current evidence suggests that eccentric exercises result in transfer to swing-phase kinematics. Other exercise modalities may be effective, but the effect of these exercises on running kinematics is unknown.

Semitendinosus and biceps femoris long head activity during the single leg bridge test in healthy individuals

INTRODUCTION

The single leg bridge test (SLBT) has been suggested as a clinical test to examine function, screen injury risk, and monitor the effectiveness of rehabilitation programes targeting the hamstring. This study aimed to determine the inter-day reliability and repeatability of both SLBT performance, semitendinosus (ST), and biceps femoris long head (BFlh) surface electromyography (sEMG) responses and characterise the BFlh and ST electrical activity during the SLBT performed until exhaustion in healthy individuals.

METHODS

Twelve physically active young men without previous hamstring injury were tested for the number of repetitions attained, and sEMG signal median frequency and amplitude in both ST and BFlh of each lower limb, randomly in two sessions, with a seven-day interval between sessions.

RESULTS

High reliability [ICC = 0.85] was found for the number of SLBT repetitions attained. Reliability of sEMG outcomes showed better results for ST (ICC = 0.62-0.91) than for BFlh (ICC = 0.39-0.81), and a high to very-high repeatability was found for both ST (ICC = 0.91-0.84) and BFlh (ICC = 0.91-0.85). sEMG median frequency decreased and amplitude increased for both BFlh (p ≤ 0.001) and ST (p ≤ 0.039) at the end of SLBT, suggesting localised fatigue.

CONCLUSIONS

The SLBT performed by healthy individuals until exhaustion proved to be reliable and to induce fatigue in both BFlh and ST, where the sEMG median frequency and amplitude can be measured on different days with acceptable reliability and high repeatability, suggesting its potential future use in both practical and clinical settings.

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.

A comparative video analysis of hamstring injuries mechanism and situational pattern in men's and women's football (soccer)

PURPOSE

To describe the injury mechanism and situational patterns of severe (absence >28 days) hamstring muscle injuries in professional male and female football (soccer) players.

METHODS

The data for males were sourced from Serie A clubs participating in both national and international competitions from 2018 to 2021. For the female cohort, hamstring injuries were identified during matches of the top national/international competitions from 2017 to 2023. Video footage was obtained, and three raters categorised injury mechanisms and situational patterns. Injuries were also examined according to the month, minute and location.

RESULTS

A total of 129 severe hamstring injuries were identified, with 64 occurring in females and 65 in males. Video analysis was possible for 29 (45%) female cases and 61 (94%) male cases. Female injuries had longer lay-off times (97.8 ± 77.1 days) than males (39.6 ± 20.9 days). Females had a higher proportion of indirect contact injuries (34%) than males (13%) and a lower proportion of non-contact injuries (66% vs. 87%). Four situational patterns were identified: running was the most common for both sexes, representing 59% of female injuries and 41% of male injuries. Over-stretching injuries were split across open and CKC scenarios but collectively explained nearly half (48%) of male injuries but only one in five (21%) female injuries. Kicking injuries had a higher proportion in females (17%) than males (10%). Injuries were more common in the second half for females and the first half for males.

CONCLUSION

Females had a higher proportion of indirect contact, running and kicking injuries and a lower proportion of non-contact and stretch-type injuries than males. Understanding injury patterns can inform tailored prevention programs, considering sex-specific differences.

LEVEL OF EVIDENCE

Level IV.

Recovery of spatio-temporal gait and functional parameters following unilateral eccentric exercise-induced muscle damage in the hamstrings

OBJECTIVES

This study aimed to analyze how spatiotemporal gait parameters, active knee extension range of motion, muscle activity, and self-perceived function change over a seven-day period in healthy individuals after exercise-induced muscle damage (EIMD) in the hamstrings.

DESIGN

Longitudinal cohort study.

METHODS

Twenty-four healthy males participated in four sessions before and after EIMD (pre-EIMD, 48 h, 96 h, and 168 h post-EIMD). A single-leg deadlift exercise was performed to provoke EIMD in the hamstrings of the dominant leg. Lower limb function perception, spatiotemporal gait parameters, active knee extension range of motion, and electromyographic (EMG) activity of the semitendinosus and biceps femoris muscles during gait and maximal isometric contraction were assessed bilaterally.

RESULTS

At 48 h, the EIMD-side showed reduced step length, active knee extension range of motion, maximal strength and EMG activity compared to baseline (P < 0.042), while increased relative EMG activity in the biceps femoris during gait (P = 0.001). At 96 h, step length and EMG activity on the EIMD-side reached similar values to those at baseline, whereas lower limb function perception and active knee extension range of motion returned to baseline state at 168 h post-EIMD. No changes over time were observed on the control-side.

CONCLUSIONS

Recovery from EIMD requires a multimodal assessment since the different parameters affected by EIMD recover at different paces. Active range of motion appears to be the last variable to fully recover. Self-perceived function should not be considered in isolation as it does not represent complete functional recovery.

Advanced MRI Approaches for Evaluating Common Lower Extremity Injuries in Basketball Players: Current and Emerging Techniques

Magnetic resonance imaging (MRI) can provide accurate and non-invasive diagnoses of lower extremity injuries in athletes. Sport-related injuries commonly occur in and around the knee and can affect the articular cartilage, patellar tendon, hamstring muscles, and bone. Sports medicine physicians utilize MRI to evaluate and diagnose injury, track recovery, estimate return to sport timelines, and assess the risk of recurrent injury. This article reviews the current literature and describes novel developments of quantitative MRI tools that can further advance our understanding of sports injury diagnosis, prevention, and treatment while minimizing injury risk and rehabilitation time. Innovative approaches for enhancing the early diagnosis and treatment of musculoskeletal injuries in basketball players span a spectrum of techniques. These encompass the utilization of T2, T1ρ, and T2* quantitative MRI, along with dGEMRIC and Na-MRI to assess articular cartilage injuries, 3D-Ultrashort echo time MRI for patellar tendon injuries, diffusion tensor imaging for acute myotendinous injuries, and sagittal short tau inversion recovery and axial long-axis T1-weighted, and 3D Cube sequences for bone stress imaging. Future studies should further refine and validate these MR-based quantitative techniques while exploring the lifelong cumulative impact of basketball on players' knees. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 2.

Effects of Photobiomodulation on Pain and Return to Play of Injured Athletes: A Systematic Review and Meta-analysis

ABSTRACT

Morgan, RM, Wheeler, TD, Poolman, MA, Haugen, ENJ, LeMire, SD, and Fitzgerald, JS. Effects of photobiomodulation on pain and return to play of injured athletes: A systematic review and meta-analysis. J Strength Cond Res 38(6): e310-e319, 2024-The aims of this systematic review and meta-analysis were to evaluate the effect of photobiomodulation (PBM) on musculoskeletal pain in injured athletes and to determine if the effects of PBM allowed injured athletes to return to play faster. Electronic databases (MEDLINE Complete, CINAHL, and SPORTDiscus, PubMed, Web of Science, and Embase) were systematically searched (up to and including November 7, 2023) for peer-reviewed randomized controlled trials (RCTs) meeting criteria. Six RCTs, representing 205 competitive and recreational athletes with a mean age of 24 years, were included in the analysis. There were 6 intervention groups using standard physical therapy (n = 1), placebo PBM (n = 4), and aloe gel (n = 1) lasting between 10 minutes and 8 weeks in duration. The level of significance set for the study was p < 0.05. Overall, the use of PBM indicated a positive effect on pain reduction for PBM vs. control groups, standardized mean differences = 1.03, SE = 0.22, 95% confidence intervals = [0.43-1.63], p = 0.0089, but the 2 RCTs found evaluating the effect of PBM on time to return to play after injury in athletes do not support a benefit. Allied healthcare professionals may use PBM to reduce pain, thus allowing an athlete to return to their normal biomechanical movement faster; however, limited evidence suggests that PBM does not reduce time to return to play after an injury.

Eccentric Hamstring Strength Imbalance among Football and Soccer Athletes

OBJECTIVES

Hamstring strain injuries (HSI) are common among football and soccer athletes. Eccentric strength imbalance is considered a contributing factor for HSI. There is, however, a paucity of data on hamstring imbalances of soccer and American football athletes as they age and advance in skill level. High school athletes will display greater interlimb discrepancies compared with collegiate and professional athletes. In addition, soccer athletes will exhibit greater hamstring asymmetry than American football athletes.

METHODS

Hamstring testing was performed on soccer and American football athletes using the NordBord Hamstring Testing System (Vald Performance, Albion, Australia). Age, sex, weight, sport specialization, and sport level were recorded. Maximum hamstring forces (N), torque (N · m), and work (N · s) were measured. Hamstring imbalance (%) was calculated by dividing the absolute value of the difference in leg forces divided by their sum. One-way analysis of variance and independent sample t tests compared measurements between athlete groups.

RESULTS

A total of 631 athletes completed measurements, including 88 high school male soccer, 25 college male soccer, 23 professional male soccer, 83 high school female soccer, 28 college female soccer, 288 high school football, and 96 college football athletes. High school soccer players displayed significantly greater imbalances for torque (P = 0.03) and work (P < 0.01) than football athletes. Imbalances for maximum force (P = 0.035), torque (P = 0.018), and work (P = 0.033) were significantly higher for male soccer athletes in high school compared with college- and professional-level athletes. Female high school soccer players had significantly higher imbalance in torque (P = 0.045) and work (P = 0.001) compared with female collegiate soccer players. Football athletes did not experience significant changes in force imbalances between skill levels.

CONCLUSIONS

High school soccer athletes exhibit greater hamstring imbalances than football athletes. Higher levels of play in soccer, for both male and female athletes, correlate with less hamstring asymmetry.

Hamstring Injuries: A Paradigm for Return to Play

Muscle injuries are the most common sports-related injuries, with hamstring involvement most common in professional athletes. These injuries can lead to significant time lost from play and have a high risk of reinjury. We review the anatomy, mechanisms of injury, diagnostic imaging modalities, and treatment techniques for hamstring injuries. We also present the latest evidence related to return to play (RTP) after hamstring injuries, including a review of articles targeted to RTP in European soccer (Union of European Football Associations), American football (National Football League), and other professional sports. Review of imaging findings in hamstring injury, grading systems for injuries, considerations for RTP, as well as advances in injury prevention, are discussed.

Hamstring muscle injuries in athletics

Hamstring muscle injuries (HMI) are a common and recurrent issue in the sport of athletics, particularly in sprinting and jumping disciplines. This review summarizes the latest literature on hamstring muscle injuries in athletics from a clinical perspective. The considerable heterogeneity in injury definitions and reporting methodologies among studies still needs to be addressed for greater clarity. Expert teams have recently developed evidence-based muscle injury classification systems whose application could guide clinical decision-making; however, no system has been adopted universally in clinical practice, yet.The most common risk factor for HMI is a previously sustained injury, particularly early after return-to-sport. Other modifiable (e.g. weakness of thigh muscles, high-speed running exposure) and non-modifiable (e.g. older age) risk factors have limited evidence linking them to injury. Reducing injury may be achieved through exercise-based programs, but their specific components and their practical applicability remain unclear.Post-injury management follows similar recommendations to other soft tissue injuries, with a graded progression through stages of rehabilitation to full return to training and then competition, based on symptoms and clinical signs to guide the individual speed of the recovery journey. Evidence favoring surgical repair is conflicting and limited to specific injury sub-types (e.g. proximal avulsions). Further research is needed on specific rehabilitation components and progression criteria, where more individualized approaches could address the high rates of recurrent HMI. Prognostically, a combination of physical examination and magnetic resonance imaging (MRI) seems superior to imaging alone when predicting 'recovery duration,' particularly at the individual level.

Bilateral Corticomotor Reorganization and Symptom Development in Response to Acute Unilateral Hamstring Pain: A Randomized, Controlled Study

Accumulating evidence demonstrates that pain induces adaptations in the corticomotor representations of affected muscles. However, previous work has primarily investigated the upper limb, with few studies examining corticomotor reorganization in response to lower limb pain. This is important to consider, given the significant functional, anatomical, and neurophysiological differences between upper and lower limb musculature. Previous work has also focused on unilateral corticomotor changes in response to muscle pain, despite an abundance of literature demonstrating that unilateral pain conditions are commonly associated with bilateral motor dysfunction. For the first time, this study investigated the effect of unilateral acute hamstring pain on bilateral corticomotor organization using transcranial magnetic stimulation (TMS) mapping. Corticomotor outcomes (TMS maps), pain, mechanical sensitivity (pressure pain thresholds), and function (maximal voluntary contractions) were recorded from 28 healthy participants at baseline. An injection of pain-inducing hypertonic (n = 14) or pain-free isotonic (n = 14) saline was then administered to the right hamstring muscle, and pain ratings were collected every 30 seconds until pain resolution. Follow-up measures were taken immediately following pain resolution and at 25, 50, and 75 minutes post-pain resolution. Unilateral acute hamstring pain induced bilateral symptom development and changes in corticomotor reorganization. Two patterns of reorganization were observed-corticomotor facilitation and corticomotor depression. Corticomotor facilitation was associated with increased mechanical sensitivity and decreased function bilaterally (all P < .05). These effects persisted for at least 75 minutes after pain resolution. PERSPECTIVE: These findings suggest that individual patterns of corticomotor reorganization may contribute to ongoing functional deficits of either limb following acute unilateral lower limb pain. Further research is required to assess these adaptations and the possible long-term implications for rehabilitation and reinjury risk in cohorts with acute hamstring injury.

Surgical treatment of distal hamstring tendon injuries yield a higher return-to-sports rate: A systematic review

PURPOSE

The purpose of this study is to compare the patient-reported outcomes and return to sports of the conservative and surgical treatment of distal hamstring tendon injuries.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, two reviewers searched PubMed, Scopus and Virtual Health Library databases in January 2023. Clinical studies evaluating conservative or surgical management outcomes of distal hamstring tendon injuries were considered eligible for this systematic review if predefined criteria were fulfilled: (1) published in English or Spanish; (2) evaluated any of the following: patient-reported outcomes, return-to-sports rate (RTS-R) or return-to-sports time (RTS-T). Data were presented in tables using absolute values from individual studies and derived pooled percentages.

RESULTS

Eighteen studies were included for 67 patients and 68 distal hamstring tendon injuries. Initially, 39 patients (58.2%) underwent surgical treatment, whereas 28 (41.8%) were treated conservatively. Among conservative treatment patients, 15 failed and had to be operated on (53.6%), all with distal semitendinosus tendon injuries. Anchor fixation was the technique of choice in 20 lesions (36.4%), tenodesis in 16 (29.1%), tenectomy in 14 (25.5%) and sutures were preferred in five (9%). Thirteen out of 28 patients (46.4%) undergoing initial conservative treatment returned to sports at a mean of 3.6 months (range 1 week to 12 months), in contrast to surgical treatment, in which 36 out of 39 patients (92.3%) returned at a mean of 4.2 months (range 6 weeks to 12 months). Additionally, 14 of 15 patients (93.3%) converted to surgical treatment after failed conservative treatment returned to sports at a mean of 7.6 months after injury.

CONCLUSION

Initial surgical treatment of distal hamstring tendon injuries yields a high RTS-R (92.3%) at a mean of 4.2 months. Furthermore, 15 out of 28 patients (53.6%) initially treated conservatively had to be operated on, delaying the RTS-T (mean 7.6 months after injury) without affecting their RTS-R.

LEVEL OF EVIDENCE

IV.

Initial Assessment and Management of Select Musculoskeletal Injuries: A Team Physician Consensus Statement

ABSTRACT

Musculoskeletal injuries occur frequently in sport during practice, training, and competition. Injury assessment and management are common responsibilities for the team physician. Initial Assessment and Management of Musculoskeletal Injury-A Team Physician Consensus Statement is title 23 in a series of annual consensus documents written for the practicing team physician. This statement was developed by the Team Physician Consensus Conference, an annual project-based alliance of six major professional associations. The goal of this document is to help the team physician improve the care and treatment of the athlete by understanding the initial assessment and management of selected musculoskeletal injuries.

Initial Assessment and Management of Select Musculoskeletal Injuries: A Team Physician Consensus Statement

ABSTRACT

Musculoskeletal injuries occur frequently in sport during practice, training, and competition. Injury assessment and management are common responsibilities for the team physician. Initial Assessment and Management of Musculoskeletal Injury-A Team Physician Consensus Statement is title 23 in a series of annual consensus documents written for the practicing team physician. This statement was developed by the Team Physician Consensus Conference, an annual project-based alliance of six major professional associations. The goal of this document is to help the team physician improve the care and treatment of the athlete by understanding the initial assessment and management of selected musculoskeletal injuries.

New prediction equations for knee isokinetic strength in young and middle-aged non-athletes

BACKGROUND

This study aimed to develop alternative prediction equations to predict isokinetic muscle strength at 60°/s based on anthropometric characteristics, including body mass, height, age, and sex for young and middle-aged non-athlete populations.

METHODS

Three hundred and thirty-two healthy non-athletic participants (174 females, 158 males) between 20 and 59 years underwent a 60°/s isokinetic knee joint concentric contraction test. Forty people were randomly selected for retesting to assess the reliability of the isokinetic instrument. Multivariate linear regression was used to establish extension peak torque (EPT) and flexion peak torque (FPT) prediction equations. Sixty extra participants were used individually to validate the prediction equations, and Bland Altman plots were constructed to assess the agreement of predicted values with actual measurements.

RESULTS

The result demonstrated that the instrument we used has excellent reliability. The multivariable linear regression model showed that body mass, age, and sex were significant predictors of PT (EPT: Adjusted R2 = 0.804, p < 0.001; FPT: Adjusted R2 = 0.705, p < 0.001). Furthermore, the equations we established had higher prediction accuracy than those of Gross et al. and Harbo et al. CONCLUSION: The equations developed in this study provided relatively low bias, thus providing a more suitable reference value for the knee isokinetic strength of young and middle-aged non-athletes.

Surgical treatment of high-grade acute intramuscular hamstring tendon injuries in athletes leads to predictable return to sports and no re-injuries

PURPOSE

The purpose of this study was to assess the post-operative return to sport and re-injury rates following surgical repair of acute, first-time, high-grade intramuscular hamstring tendon injuries in high level athletes.

METHODS

Patients were identified using the databases of two sports surgeons. Once patients were identified their clinical notes and imaging were reviewed to confirm that all patients had injuries to the intramuscular portion of the distal aspect of the proximal biceps femoris tendon. All imaging was reviewed by an experienced musculoskeletal radiologist to confirm diagnosis. Surgery for such injuries was indicated in high-level athletes presenting with acute hamstring injuries. All patients were operated on within 4 weeks. Outcomes included Tegner scores, return to sport, Lower Extremity Functional Score (LEFS), current hamstring symptoms and complications including re-injury.

RESULTS

Eleven injuries (10 patients) were included in the study. All patients were male and Australian Rules Football players. Six patients were professional athletes and 4 semi-professional athletes. Median age was 24.5 (range 21-29) and median follow-up period was 33.7 months (range; 16-65). 91% were British Athletic Muscle Injury Classification (BAMIC) 3c and 9% were BAMIC 4c. 91% were classed as MR2 and 9% as MR3 on the simplified four-grade injury classification. Athletes achieved return to play (RTP) at an average of 3.1 months (SD 1.0) post repair. All but one patient achieved a Tegner score equal to pre-injury levels. Maximum LEFS was achieved by all patients. Minor pain scores (all with VAS < 1/10) on sciatic and functional stretch were recorded in 36% and 27% of patients respectively, with subtle neural symptoms (9%) and subjective tightness (36%) also noted. There were no surgical complications in our patient cohort. No patients had a re-injury or re-operation.

CONCLUSIONS

Surgical repair of high-grade intramuscular tendon injuries of the biceps femoris hamstring muscle in athletes resulted in high levels of return to pre-injury sporting levels and no re-injuries. The intra-muscular tendon should be scrutinized when assessing hamstring injuries in elite sport and offer surgery in high-grade cases.

LEVEL OF EVIDENCE

IV.

Intramuscular Tendon Injuries of the Hamstring Muscles: A More Severe Variant? A Narrative Review

Hamstring strain injuries (HSI) are one of the most common sport-related injuries. They have a high injury burden and a high recurrence rate. The development of novel muscle injury grading systems has provided new insights into the possible impact of injury location on the time to return to play (TTRTP) and re-injury following HSI. In particular, injuries to the intramuscular tendon (IMT) may be present in up to 41% of all HSI and have been described as a 'serious thigh muscle strain'. Re-injury rates as high as 60% have been described in elite track and field athletes, as well as prolonged TTRTP. A systematic search was carried out using appropriate keywords to identify articles reporting on HSI involving the IMT in athletes. The primary aim was to determine whether IMT injuries warrant being classified as a distinct clinical entity with different expected outcomes to other hamstring muscle injuries. This narrative review summarises the existing evidence on: (1) the anatomy of the IMT and its response to injury; (2) the role of MRI and novel grading scales in IMT injury management (3) clinical assessment of IMT injuries, (4) TTRTP and re-injury rates across sports following IMT, (5) conservative rehabilitation and the role of specific 'IMT-oriented' strategies, and (6) indications for and approaches to surgery. The review found that important clinical outcomes such as re-injury rates and TTRTP vary across populations, cohorts and sports which suggest that outcomes are specific to the sporting context. Bespoke rehabilitation, tailored to IMT injury, has been shown to significantly reduce re-injuries in elite track and field athletes, without compromising TTRTP. Continued prospective studies across other sports and cohorts, are warranted to further establish relevant clinical findings, indications for surgical intervention and outcomes across other sporting cohorts.

Comparisons of musculoskeletal injuries among three different modalities of Taekwondo (Kyorugi, Poomsae, and Shibum): a one-year follow-up prospective epidemiologic study

The purpose of the study was to report the injury rates and characteristics (body location, type, mechanism, and severity) of musculoskeletal injuries in Kyorugi, Poomsae, and Shibum. A total of 137 Korean collegiate Taekwondo players - Kyorugi (n = 44), Poomsae (n = 46), and Shibum (n = 47) - were prospectively studied in 2019. Injury rates per 1,000 athlete-exposures (AEs) and time-exposures (TEs) during training and competition were calculated. Additionally, body location, type, mechanism, and severity of injury were analysed. The highest injury rate was recorded in Poomsae (172.0/1,000 AEs and 79.5/1,000 TEs) followed by Kyorugi (47.1/1,000 AEs and 25.9/1,000 TEs) and Shibum (57.5/1,000 AEs and 17.0/1,000 TEs). The frequently injured body location was the thigh (Kyorugi = 17%; Poomsae = 25%; Shibum = 18%). The common injury types were muscle cramps/spasms in Kyorugi (33%) and Poomsae (59%), and sprain in Shibum (41%). The common injury mechanisms were gradual onset in Kyorugi (40%) and Shibum (49%), and non-contact trauma in Poomsae (91%). Regarding the severity, the number of days from the injury onset to recovery > 1 week were higher in the order of Kyorugi (78%), Shibum (54%), and Poomsae (28%). Our data provide preliminary evidence that different injury prevention strategies should be applied to each modality of Taekwondo.

Proximal endoscopic repair of the hamstring tendons: a cadaveric anatomical study of posterior hip portals

Arthroscopy and endoscopic hip surgery have attracted increasing attention in the orthopedic field. In the case of arthroscopy, portals and their relationships with neurovascular bundle structures at risk are well established. However, studies on endoscopic portals used for the repair of hamstring tendon injuries are insufficient. Hamstring injuries are the most common muscle injury in sports medicine, and up to 12% can present as a tendon rupture. Endoscopic surgery is advantageous because it has a lower rate of bleeding and avoids excessive handling of the gluteal muscles. The objective of this study is to perform an anatomical evaluation of endoscopic portals for hamstring repair and measure their distance to neurovascular structures-mainly sciatic nerve and posterior femoral cutaneous nerve (PFCN). Fifteen hips from frozen and formalized cadavers were evaluated. Specimens that showed any modification in their anatomy were excluded. Portals were simulated using Steinmann pins, and anatomical dissection was performed. Distances from neurovascular structures were measured using a digital caliper. Four male cadaver hips (26%) and eleven female cadaver hips (74%) were included. Two dissected hips presented PFCN injury through the posterolateral portal- mean 20.28 mm (±8.14), and one through the distal accessory portal- 21.87 mm (±12.03). The injury rate for PFCN was 3/15 or 20%. None of the portals presented sciatic nerve injury. Conclusion: There is an imminent risk of nerve injury to the PFCN by performing the lateral portals for hamstring repair. To avoid this, we recommend starting the procedure through the most medial (posteromedial) portal, and the other portals must be performed under direct visualization.

Running demands in club, regional, national, and international provincial New Zealand rugby union competitions

The demands of national and international professional rugby union matches are well established, however, there has not been a comparative study investigating running demands in New Zealand teams playing in club (amateur), Heartland Championship (semi-professional Div 2), the Mitre 10 Cup (semi-professional Div 1) or Super Rugby (professional) competitions. This information could enable specific training and rehabilitation that programmes to be developed to meet the needs of players in the different competitions. Players wore 10 Hz GPS units during games for one rugby season to determine absolute (m) and relative (m.min^-1) measures for total distance, running volume (∼≥7 km·h^-1) and high intensity running (∼≥16 km·h^-1). There were typically minimal differences (1-2 m.min^-1) in running distance measures between amateur level front row forwards and inside backs compared to players in these positions at higher levels of competition. Therefore, amateur players in these positions may find the transition to higher competitions less challenging with respect to running load. In contrast, amateur outside backs and back row forwards may find the increased pace of higher levels of competition more challenging due to typically covering significantly less running and high intensity running distances in amateur games. Differences for half backs were more variable between the levels of competition. Based on our results, it cannot be assumed that amateur rugby has lower running demands than higher competitions or that there is a continuum of increased running demands with increasing competition levels, as some playing positions in the semi-professional (Div 2) (second lowest level of competition) team recorded the largest values for total distance, running and high intensity running. Therefore, the specificity of running demands in a position and competition need to be considered individually for each player when transitioning between competitions. The practice and perception of returning a professional player to amateur club rugby due to the belief that running loads being lower may also be flawed, as we found considerable positional variation in running demands within-and-between competitions.

Relationship between anatomical injury site of rectus femoris muscle strain and time taken to return to play in Japanese professional soccer players

PURPOSE

The rectus femoris has three myotendinous or myoaponeurosis junctions and causes three types of muscle strain anatomically. We aimed to investigate the anatomical injury site of the rectus femoris muscle strain in professional soccer players as well as the characteristic findings on magnetic resonance imaging (MRI) and to evaluate its relationship with the time taken to return to play at competition levels.

METHODS

Thirteen Japanese professional soccer players who sustained injuries to the rectus femoris were included in this study. The mechanism of injury, anatomical injury site, severity, absence of hematomas, and time taken to return to competition were evaluated.

RESULTS

Ten patients were injured while kicking and three while sprinting. The anatomical injury site was the origin aponeurosis in two cases, intramuscular tendon in eight cases, and distal aponeurosis in three cases. The severity was one-degree in three cases and two-degree in 10 cases. Hematomas were observed in five cases. Cases with injuries caused by sprinting, two-degree injuries, or clear hematomas were associated with significantly longer periods of return to play than the other cases. Additionally, patients with distal aponeurosis-type injuries tended to take a long time to return to the competition.

CONCLUSIONS

In rectus femoris muscle strain, it is important to evaluate the anatomical injury site, severity, and absence of hematomas on MRI. Not only the injury mechanism, a clear hematoma, and high severity but also distal aponeurosis injuries may be associated with long periods of return to play at competition levels.

Neuromuscular characteristics of agonists and antagonists during maximal eccentric knee flexion in soccer players with a history of hamstring muscle injuries

BACKGROUND

Muscle strain injuries (MSIs) in the hamstrings are among the most prevalent injuries in elite soccer. We aimed to examine the relation between biomechanical maladaptation in eccentric strength and neuromuscular factors separated by their time and frequency domains.

METHODS

20 elite soccer players with a previous history of unilateral MSI in the M. biceps femoris (BF) long head and 20 without MSI participated. Knee flexion torques, rate of torque development (RTD) and electromyographic signals (EMG) of the BF, the M. semitendinosus (SMT) and knee extensors were obtained during unilateral maximal eccentric knee flexions performed at slow (30°/s) and fast (120°/s) angular speeds. Root mean squares and mean power frequency (MF) was calculated.

RESULTS

In the group with a history of MSI, reduced maximal eccentric flexion torque (slow eccentrics -8±11, p<0.05; fast eccentrics -18±13 N*m, p<0.05) and RTD (-33±28 N*m/s, p<0.05; -95±47 N*m/s, p<0.05) concomitantly occurred with diminished agonistic myoelectrical activities (-4±5% of MVC, p<0.05; -10±7% of MVC, p<0.05) and MFs (-24±13 Hz, p<0.05; -24±18 Hz, p<0.05) in the BF. Simultaneously, antagonistic myoelectric activity was elevated (+4±3% of MVC, p<0.05; +3±3% of MVC, p<0.05) in MSI affected legs as compared to unaffected legs for both eccentric contractions. Deficits in myoelectrical activity (r2 = 0.715, p<0.05; r2 = 0.601, p<0.05) and MF (r2 = 0.484, p<0.05; r2 = 0.622, p<0.05) correlated with deficits in maximal torque in the affected leg in the MSI group. Analysis of SMT demonstrated no significant differences.

CONCLUSION

Positive relationships between neuromuscular deficits and the reduced eccentric strength profile underpin neuronal inhibition after MSI. This persistent involvement of dysfunctional synergist and antagonist neural hamstring function in strength weakness is of clinical relevance in sports medicine for prevention and rehabilitation.

Application of Shear-Wave Elastography in the Evaluation of Hamstring Stiffness in Young Basketball Athletes

Background

Previous literature has postulated a relationship between greater hamstring stiffness and a higher risk of sustaining injury. Shear wave elastography (SWE) presents a relatively new means for non-invasive evaluation of soft tissue elasticity pre- and post- injury or intervention.

Purpose

1. To establish baseline hamstring stiffness measures for young competitive athletes and (2) determine effect of targeted neuromuscular training (TNMT) on shear wave stiffness of the hamstring.

Study Design

Un-blinded, prospective, non-randomized, cohort study.

Methods

Six-hundred forty-two lower extremities from 321 high school and collegiate basketball athletes (177 F: 139 M) were examined for hamstring stiffness prior to the start of their competitive basketball season. Teams were cluster assigned to either the control or intervention (TNMT) group. Subjects in the control group underwent regular season activities as directed, with no influence from the research team. For the TNMT group, the research team introduced a hamstring targeted dynamic warm-up program as an intervention focused on activating the hamstring musculature.

Results

Collegiate status was significant to hamstring stiffness for both sexes (p ≤ 0.02), but hamstring stiffness did not correlate to age or sex (r2 ≤ 0.08). Intervention was a significant factor to hamstring stiffness when the hip was positioned in extension (p ≤ 0.01), but not in deeper flexion (p = 0.12). This effect was sex-specific as TNMT influenced hamstring stiffness in females (p = 0.03), but not in males (p ≥ 0.13). Control athletes suffered three HAM injuries; TNMT athletes suffered 0 hamstring injuries.

Conclusion

Higher SWE measurements correlated with increased risk of injury, male sex, and collegiate athletics. TNMT intervention can lessen muscle stiffness which may reduce relate to injury incidence. Intervention effectiveness may be sex specific.

Level of Evidence

II.

Hamstring Injury Rehabilitation and Prevention in the Female Athlete

Hamstring injuries (HSIs) are common in female athletes and are associated with a lengthy recovery period and a high rate of reinjury. Currently, the majority of existing literature investigating HSI rehabilitation has been conducted using male participants. However, female athletes display intrinsic anatomical and biomechanical differences compared to males that influences the way this population experiences HSIs and HSI rehabilitation. HSI rehabilitation and injury prevention guidelines for female athletes must take these differences into account. Female athletes display anatomical differences such as increased anterior pelvic tilting, gluteus maximus weakness, an increased pelvic width-to-femoral length ratio, and an increased degree of femoral anteversion, all of which can predispose females to HSIs. Maneuvers designed to strengthen the gluteal musculature and transverse abdominis can overcome these risk factors. Females show increased joint laxity and a greater range of motion of hip flexion and internal rotation compared to males. Females have lower passive hamstring stiffness than males, therefore hamstring flexibility exercises may not be as necessary during rehabilitation for females as in the male athlete population. Female athletes may instead benefit from trunk stabilization exercises and agility training due to neuromuscular control deficits that arise from the maturation and growth of the female pelvis. Existing literature on hamstring injury prevention shows consistent use of the Nordic Hamstring Exercise and balance exercises may reduce the risk of sustaining an HSI in both males and females, though more studies are needed to ascertain the optimal regimen for injury prevention in the female athlete population specifically. The goal of this clinical commentary is to discuss sex-specific anatomic and biomechanical differences of the lumbar, pelvic, and hip regions with the aim of providing guidelines for rehabilitation and injury prevention of HSIs in female athletes.

Level of Evidence

5.

Is Myofascial Decompression Effective at Increasing Hamstring Flexibility in the Athletic Population? A Critically Appraised Topic

CLINICAL SCENARIO

There are a variety of therapeutic modalities used to treat flexibility issues in athletes, which can be the main cause of hamstring injuries. Myofascial decompression is one modality used to treat these patients.

FOCUSED CLINICAL QUESTION

Is myofascial decompression effective at increasing hamstring flexibility in the athletic population? Summary of Search, "Best Evidence" Appraised, and Key Findings: The literature was searched for studies of level 2 evidence or higher that investigated the use of myofascial decompression to increase hamstring flexibility, that were published in the last 5 years. Two high-quality randomized controlled trials were included and one cohort study.

CLINICAL BOTTOM LINE

There is not enough consistent, clinically significant, high-level evidence to support the use of myofascial decompression to increase hamstring flexibility.

STRENGTH OF RECOMMENDATION

There is level B evidence to support that myofascial decompression is effective at increasing hamstring flexibility.

Early introduction of high-intensity eccentric loading into hamstring strain injury rehabilitation

OBJECTIVES

This study aimed to investigate the number of days following hamstring strain injury (HSI) taken to introduce high-intensity eccentric loading (HIEL) into rehabilitation based on exercise-specific progression criteria, and whether pain resolution during isometric knee flexion strength testing occurred before or after this milestone.

DESIGN

Cohort study.

METHODS

We included 42 men (mean ± sd; age = 26 ± 5 years; height = 181 ± 8 cm; mass = 86 ± 12 kg) with HSIs, who performed fully supervised rehabilitation twice per week until they met return to play clearance criteria. Isometric knee flexion strength testing was completed before every rehabilitation session and HIEL was introduced via the Nordic hamstring exercise and unilateral slider once participants could perform a bilateral slider through full eccentric knee flexion range of motion. We reported the median (IQR) number of days following HSI taken to introduce HIEL, along with participant's pain rating during isometric knee flexion strength testing before that rehabilitation session. We also reported the median (IQR) number of days following HSI taken for participants to achieve pain resolution during isometric knee flexion.

RESULTS

HIEL was introduced 5 (2-8) days following HSI, despite 35/42 participants reporting pain during isometric knee flexion strength testing immediately prior to that rehabilitation session, which was rated as 3.5 (3-5) on a 0-10 numeric rating scale. Pain resolution during isometric knee flexion strength testing was achieved 11 (9-13) days following HSI.

CONCLUSION

HIEL can be safely introduced into early HSI rehabilitation based on exercise-specific progression criteria, without needing to wait for pain resolution during isometric knee flexion strength testing before doing so.

Effect of COVID-19 on Injury Rates and Timing in the National Football League

Background:

The coronavirus 2019 (COVID-19) pandemic resulted in the cancellation of the 2020 National Football League (NFL) preseason and a decreased preseason roster size. The effect of this disruption on athlete injury rates is unknown.

Purpose/Hypothesis:

The purpose was to quantify the rates of anterior cruciate ligament (ACL), Achilles tendon, and hamstring tendon injuries in NFL players before and after the COVID-19 pandemic. We hypothesized that injury rates in the 2020 season would be higher than those seen prepandemic.

Study Design:

Descriptive epidemiology study. Level of evidence, 4.

Methods:

An online search using publicly available data was carried out to identify all NFL players who sustained an ACL, Achilles tendon, or hamstring tendon injury between April 1, 2017, and March 31, 2021. Data collected included player characteristics as well as career and season of injury workloads.

Results:

The number of Achilles tendon (27 vs 20; P = .024) and hamstring tendon (186 vs 149; P < .001) injuries, respectively, in the 2020 NFL season were significantly higher than the average of the 2017 to 2019 seasons. However, the number of ACL injuries sustained remained constant (43 vs 46; P = .175). More than half (52.9%) of ACL injuries in the 2017 to 2019 seasons occurred in the preseason, while most of the injuries (34.9%) in the 2020 season occurred in weeks 1 to 4. There was no player characteristic or career workload variable collected that was significantly different for players who sustained an ACL, Achilles tendon, or hamstring tendon injury in the 2020 NFL season compared with the 2017 to 2019 seasons.

Conclusion:

In the 2020 NFL season, the number of Achilles tendon and hamstring tendon injuries rose while the number of ACL injuries remained constant compared with the 2017 to 2019 seasons. Injuries that occurred during the first 4 games of the 2020 NFL season were consistent, with higher rates of injuries seen in the preseason in previous years.

The Immediate Effect of Adding Lumbar Mobilization to A Static Stretching Program on Hamstrings Range of Motion: An Exploratory Study

A contributing risk factor and a byproduct of a hamstrings strain is limited hamstrings range of motion (ROM). Some evidence supports static stretching (SS) and lumbar spinal mobilization therapy (LSMT) as an effective means for increasing hamstrings ROM. However, the efficacy of combining LSMT and SS for increasing hamstrings ROM is unknown. The objective of the study is to quantify the immediate effects of the combination of LSMT and SS compared to LSMT and SS on hamstrings ROM in a healthy population. Thirty participants were randomized by block allocation into one of three intervention groups: (1) LSMT (unilateral lumbar PA mobilization at L-4); (2) SS; or (3) combination of LSMT and SS. Hamstrings ROM was measured pre- and post-intervention by the active knee extension test (AKET). There was no group-by-time interaction effect (p = 0.871). Within group analysis revealed a significant statistical change and a large effect size: LSMT (p = .037, RCI = 3.36, d = 0.771); SS (p = 0.035, RCI = 2.94, d = 0.781); combination (p = .005, RCI = 4.21, d = 1.186. The findings suggest that the combination of LSMT and SS does not have a further effect on hamstrings ROM compared to the individual results of LSMT or SS.

CHARACTERISTICS OF SPORTS INJURIES IN TAEKWONDO ATHLETES IN PHYSICAL TRAINING

ABSTRACT Introduction: Taekwondo is one of the main events of the Olympic Games. It mainly uses hands and feet for fighting or confrontation and the competition is extremely fierce. Therefore, Taekwondo is more prone to muscle, bone, and joint sports injuries. Objective: To understand the characteristics of taekwondo sports injuries. Methods: Using the literature and questionnaire survey methods, mathematical statistics is used to investigate the sports injuries of young Taekwondo athletes. Results: Among 100 young Taekwondo athletes, 93individuals had different degrees of sports injuries, accounting for 93%, and 7had no sports injuries, accounting for only 7%. The total number of injuries was 160 or 1.6injuries per capita. Conclusions: Athletes should improve their ideological understanding and training level and pay attention to the timely treatment of acute injuries, which can effectively reduce sports injuries. Level of evidence II; Therapeutic studies - investigation of treatment results.

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.

Distal Gracilis Tear in an Equestrian

ABSTRACT

A 61-yr-old female equestrian presented after 2 wks of left medial thigh pain, which developed suddenly while exiting a car. She denied any history of recent trauma or falls. On examination, she was found to have tenderness at the left distal medial thigh with a palpable region of decreased tissue volume at the gracilis myotendinous junction. Point-of-care ultrasound and magnetic resonance imaging confirmed a high-grade partial thickness tear of the left distal gracilis at the myotendinous junction, as well as pes anserine bursal distention. She received physical therapy and underwent a 1-time ultrasound-guided corticosteroid injection to the left pes anserine bursa. At follow-up, her symptoms had significantly improved, and she had returned to horseback riding after 12 wks. Isolated gracilis myotendinous tear is a rare condition, and this is a unique case with an atypical mechanism of injury as gracilis injuries have only been reported during vigorous exercise-related activities rather than transitional movements. This case illustrates the potential increased risk of distal gracilis injury after repetitive corticosteroid injections (genicular nerve blocks and radiofrequency lesioning) in a patient who was also likely predisposed to gracilis microtrauma due to her equestrian activities. Gracilis injury should be considered in the differential diagnosis of distal medial thigh pain, especially in cases with similar interventional and recreational profiles.

Establishing Reference Values for Isometric Knee Extension and Flexion Strength

Single-joint isometric and isokinetic knee strength assessment plays an important role in strength and conditioning, physical therapy, and rehabilitation. The literature, however, lacks absolute reference values. We systematically reviewed the available studies that assessed isometric knee strength. Two scientific databases (PubMed and PEDro) were searched for the papers that are published from the inception of the field to the end of 2019. We included studies that involved participants of both genders and different age groups, regardless of the study design, that involved isometric knee extension and/or flexion measurement. The extracted data were converted to body-mass-normalized values. Moreover, the data were grouped according to the knee angle condition (extended, mid-range, and flexed). A meta-analysis was performed on 13,893 participants from 411 studies. In adult healthy males, the pooled 95% confidence intervals (CI) for knee extension were 1.34–2.23Nm/kg for extended knee angle, 2.92–3.45Nm/kg for mid-range knee angle, and 2.50–3.06Nm/kg for flexed knee angle, while the CIs for flexion were 0.85–1.20, 1.15–1.62, and 0.96–1.54Nm/kg, respectively. Adult females consistently showed lower strength than adult male subgroups (e.g., the CIs for knee extension were 1.01–1.50, 2.08–2.74, and 2.04–2.71Nm/kg for extended, mid-range, and flexed knee angle condition). Older adults consistently showed lower values than adults (e.g., pooled CIs for mid-range knee angle were 1.74–2.16Nm/kg (male) and 1.40–1.64Nm/kg (female) for extension, and 0.69–0.89Nm/kg (male) and 0.46–0.81Nm/kg (female) for flexion). Reliable normative for athletes could not be calculated due to limited number of studies for individual sports.

Biceps Femoris Activation during Hamstring Strength Exercises: A Systematic Review

BACKGROUND

The aim of the study was to systematically evaluate the biceps femoris long head activation across cross-sectional hamstring strength exercise studies.

METHODS

A systematic review design was followed. The search strategy conducted in PubMed, Cochrane Library, and Web of Sciences databases found a total of 3643 studies. Once inclusion and exclusion criteria were applied, 29 studies were finally included in this systematic review. A total of 507 participants and 114 different exercises were analyzed. Exercises were evaluated individually and grouped into several categories: Nordics, isokinetic exercises, lunges, squats, deadlifts, good mornings, hip thrusts, bridges, leg curls, swings, hip and back extensions, and others.

RESULTS

Results showed the isokinetic and Nordic exercises as the categories with highest biceps femoris activation (>60% of Maximal Voluntary Isometric Contraction). Nordic hamstring exercise ankle dorsiflexion was the exercise that achieved the highest biceps femoris long head activation (128.1% of its Maximal Voluntary Isometric Contraction).

CONCLUSIONS

The results from this systematic review suggest that isokinetic and Nordic exercises seem to be the best option to activate biceps femoris long head. Future studies evaluating the implementation of these exercises in prevention programs are needed.

Consensus on tasks to be included in a return to work assessment for a UK firefighter following an injury: an online Delphi study

OBJECTIVE

The aim was to provide a consensus tasks needed to be included in a return to work assessment for operational firefighters.

METHODS

A two round online Delphi study was conducted with twenty-four participants including firefighters, service fitness advisers and occupational health managers. A consensus was set at 70% agreement. In round one, participants completed an online survey relating to tasks to be included during a return to work assessment for firefighters following an injury. Round two was an online consensus meeting to discuss the tasks where consensus was not achieved.

RESULTS

A consensus was reached for ten of the thirteen tasks, including the number of repetitions required when lifting a light portable pump and climbing a ladder. A consensus was reached for the total distance equipment which should be carried. This included carrying a ladder, a hose and a light portable pump.

CONCLUSIONS

This study has provided a consensus for tasks to be included when assessing a firefighter for return to work. Further research is needed to understand how to use this assessment optimally.

A comparison of ground reaction force waveforms and step length between recreational endurance runners with hamstring injuries and healthy controls

BACKGROUND

Acute hamstring injuries during sprinting have been attributed, in part, to the ground reaction forces experienced during early stance. However, no studies have investigated the factors associated with overuse hamstring injuries in endurance runners. Our purpose was to compare early stance ground reaction forces and step length between runners with overuse hamstring injuries and healthy controls.

METHODS

23 runners (5 men/ 18 women) who presented to a running clinic with an overuse hamstring injury were matched with healthy controls for sex, running speed and age. All participants ran on an instrumented treadmill, embedded with force plates. A 3-min warm-up was given, at a self-selected training pace, followed by 16-s of ground reaction force data collection (≈20 strides). Statistical parametric mapping was used to compared ground reaction force waveforms. Additionally, discrete force variables were calculated, including vertical average/instantaneous. Mean comparisons for discrete ground reaction force variables and step length were performed.

FINDINGS

Differences in ground reaction force waveforms did not reach statistical significance (p > 0.05). However, mean vertical loading rates were found to be higher in the Hamstring Injury group compared to Controls (p = 0.03-0.04) with small to moderate effect sizes (d = 0.47-0.52). No differences were found in mean step length.

INTERPRETATION

These results provide evidence that vertical loading rates may be associated with overuse hamstring injuries. However, further research is needed to identify the contribution of joint kinematics/kinetics and muscle activity.

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.

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.

Study protocol for a double-blind, randomised placebo-controlled trial evaluating clinical effects of platelet-rich plasma injection for acute grade-2 hamstring tear among high performance athletes

INTRODUCTION

Hamstring injury among athletes often results in significant morbidity. Currently, there are controversies regarding the clinical use of platelet-rich plasma (PRP) for the treatment of acute hamstring injury.

METHODS AND ANALYSIS

This study is a single-centre double-blind randomised placebo-controlled trial. Sixty-eight patients will be randomised to receive under ultrasound guidance either a single injection of leucocyte-rich PRP (LR-PRP) or normal saline. All patients will undergo a standardised hamstring rehabilitation programme under the supervision of a sports physiotherapist. Outcome data will be collected before intervention (baseline), and thereafter on a weekly basis. The primary outcome measure is the duration to return-to-play. It is defined as the duration (in days) from the date on which the injury occurred until the patients were pain-free, able to perform the active knee extension test and have regained hamstring muscle strength. Secondary outcome measures include assessment of pain intensity and the effect of pain on to day-to-day functions using the self-reported Brief Pain Inventory-Short Form questionnaire. Both the primary and secondary outcomes were assessed at baseline and thereafter once a week until return to play. Also, hamstring injury recurrence within the first 6 months after recovery will be monitored via telephone. The results of this study will provide insights into the effect of LR-PRP in muscle and may help to identify the best PRP application protocol for muscle injuries.

ETHICS AND DISSEMINATION

Ethics approval were obtained from the Medical Research Ethics Committee of the University of Malaya Medical Centre. Results of this trial will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ISRCTN76844299.

Interrogating cortical representations in elite athletes with persistent posterior thigh pain - New targets for intervention?

OBJECTIVES

Hamstring injuries in athletes can lead to significant time away from competition as a result of persistent posterior thigh pain. These cases are often difficult to treat as the state of the tissues alone cannot explain symptoms. In non-athletic populations with persistent pain, disruptions to tactile, proprioceptive, and spatial cortical representations exist, which has led to promising brain-based treatments. Here, we explored whether athletes with persistent posterior thigh pain also display impairments in these cortical representations.

DESIGN

Cross-sectional study.

METHODS

Fourteen male professional athletes with persistent posterior thigh pain ('Patients') and 14 pain-free age, sport, body mass index and level-matched controls ('Controls') participated. The tactile cortical representation was assessed using two-point discrimination (TPD) threshold and accuracy of tactile localisation; the proprioceptive cortical representation was assessed using a left/right judgement task; spatial processing was assessed using an auditory detection task.

RESULTS

TPD thresholds were similar for Patients and Controls (p=0.70). Patients were less accurate at localising tactile stimuli delivered to their affected leg, slower to make left/right judgements when the lower limb image corresponded to the side of their affected leg, and less accurate at detecting auditory stimuli delivered near their affected leg, when compared to their healthy leg or to the leg of Controls (p<0.01 for all).

CONCLUSIONS

Leg-specific tactile, proprioceptive, and spatial processing deficits exist in athletes with persistent posterior thigh pain. That these processing deficits exist despite rehabilitation and normal tissue healing time suggests they may play a role in the persistence of posterior thigh pain.

Pronounced Heterotopic Ossifications after Traumatic Hamstring Rupture: Is an Ossification Prophylaxis Useful?

Hamstring injuries include a wide range of injuries and affect mainly athletes with high eccentric loads (football, athletics, rugby, climbing). According to the latest literature, unrecognized traumatic ruptures can cause permanent discomfort and may be associated with a poorer postoperative outcome when delayed surgical therapy is performed. Heterotopic ossifications (HO) after hamstring rupture have been described in individual case reports and smaller studies so far. Heterotopic ossifications are mainly known in hip surgery and elbow fractures. In this case report, a 48-year-old patient presented with an increasing swelling with hardening in the area of the right ischial tuberosity. One year before, an impact trauma was the reason for a traumatic hamstring rupture which was diagnosed with a delay. The HO was excised and the tendon refixed with two suture anchors. By limiting the range of motion with a hip-knee orthosis for 9 weeks, a regular postoperative healing process was observed. Heterotopic ossifications after hamstring ruptures have been reported repeatedly but have not been evaluated in any major study so far. It should therefore be considered whether prophylaxis with NSAIDs should be used for conservatively and surgically treated hamstring ruptures, analogous to the ossification prophylaxis for hip endoprostheses or fractures in the elbow region.

Effects of eccentric training at long-muscle length on architectural and functional characteristics of the hamstrings

Hamstring strain injuries during sprinting or stretching frequently occur at long-muscle length. Yet, previous research has mainly focused on studying the effectiveness of eccentric hamstring strengthening at shorter muscle length on hamstring performance, morphology, and hamstring strain injury risk factors. Here, we evaluated the effects of 6-week eccentric hamstring training at long-muscle length on functional and architectural characteristics of the hamstrings. Healthy and injury-free participants (n = 40; age 23.7 ± 2.5 years) were randomly assigned to control or intervention group. Training intervention consisted of 12 sessions with two eccentric hamstring exercises in a lengthened position. Outcome measures included isokinetic and isometric knee flexion peak torque, Nordic hamstring exercise peak torque, voluntary activation level, and countermovement jump performance. Ultrasonography was used to determine muscle thickness, pennation angle, and fascicle length of biceps femoris long head (BFlh). A significant time × group interaction effect was observed for all measured parameters except countermovement jump performance and muscle thickness. The training intervention resulted in increased concentric and eccentric knee flexion peak torque at 60°/s (d = 0.55-0.62, P = .02 and .03) and concentric peak torque at 180°/s (d = 0.99, P = .001), increased isometric knee flexion peak torque (d = 0.73, P = .008) and Nordic hamstring exercise peak torque (d = 1.19, P < .001), increased voluntary activation level (d = 1.29, P < .001), decreased pennation angle (d = 1.31, P < .001), and increased fascicle length (d = 1.12, P < .001) of BFlh. These results provide evidence that short-term eccentric hamstring strengthening at long-muscle length can have significant favorable effects on various architectural and functional characteristics of the hamstrings.

Single-Leg Roman Chair Hold Is More Effective Than the Nordic Hamstring Curl in Improving Hamstring Strength-Endurance in Gaelic Footballers With Previous Hamstring Injury

Macdonald, B, O'Neill, J, Pollock, N, and Van Hooren, B. Single-leg Roman chair hold is more effective than the Nordic hamstring curl in improving hamstring strength-endurance in Gaelic footballers with previous hamstring injury. J Strength Cond Res 33(12): 3302-3308, 2019-Poor hamstring strength-endurance is a risk factor for hamstring injuries. This study investigated the effectiveness of the single-leg Roman hold and Nordic hamstring curl in improving hamstring strength-endurance. Twelve Gaelic footballers (mean ± SD age, height, and mass were 25.17 ± 3.46 years, 179.25 ± 5.88 cm, 85.75 ± 4.75 kg, respectively) with a history of hamstring injury were randomized into 2 groups that performed 6 weeks of either Nordic hamstring curl or single-leg Roman chair hold training. The single-leg hamstring bridge (SLHB) was measured before and after intervention. The Roman chair group showed a very likely moderate magnitude improvement on SLHB performance for both legs (23.7% for the previously injured leg [90% confidence interval 9.6-39.6%] and 16.9% for the noninjured leg [6.2-28.8%]). The Nordic curl group showed a likely trivial change in SLHB performance for the noninjured leg (-2.1% [-6.7 to 2.6%]) and an unclear, but possibly trivial change for the previously injured leg (0.3% [-5.6 to 6.6%]). The Roman chair group improved very likely more with a moderate magnitude in both the noninjured (19.5% [8.0-32.2%]) and the previously injured leg (23.3% [8.5-40.0%]) compared with the Nordic curl group. This study demonstrated that 6-week single-leg Roman chair training substantially improved SLHB performance, suggesting that it may be an efficacious strategy to mitigate hamstring (re-) injury risk. Conversely, 6-week Nordic curl training did not substantially improve SLHB performance, suggesting this may not be the intervention of choice for modifying this risk factor.

The immediate effect of IASTM vs. Vibration vs. Light Hand Massage on knee angle repositioning accuracy and hamstrings flexibility: A pilot study

INTRODUCTION

The effectiveness of novel soft-tissue interventions relative to traditional ones requires further exploration. The purpose of this pilot study was to evaluate the immediate effect of Instrument Assisted Soft Tissue Mobilization (IASTM) compared to Vibration Massage or Light Hand Massage on hamstrings' flexibility and knee proprioception.

METHODS

16 healthy non-injured male participants (mean age 23.7 years, height 1.80 cms and body mass 77.7 kg) were randomly assigned to the following interventions: (a) 5min IASTM, (b) 5min Vibration Massage and (c) 8min Light Hand-Massage, sequentially delivered to all participants with an in-between 1-week time interval. A single application of each intervention was given over the hamstrings of their dominant leg (repeated measures under 3 different experimental conditions). An active knee angle reproduction proprioception test and the back-saver sit and reach flexibility test were performed before and immediately after each intervention. Reliability of outcomes was also assessed.

RESULTS

Reliability for flexibility (ICC_3,1 = 0.97-0.99/SEM = 0.83-1.52 cm) and proprioception (ICC_3,1 = 0.83-0.88/SEM = 1.63-2.02°) was very good. For flexibility, statistically significant immediate improvement (p < 0.001) was noted in all 3 groups (1.61-3.23 cm), with no between-group differences. For proprioception, improvement in the IASTM (2.12°), Vibration Massage (0.32°) and Light Hand-Massage (1.17°) conditions was not statistically significant; no between-group differences were also evident.

CONCLUSIONS

Our findings indicate that muscle flexibility was positively influenced immediately after a single intervention of IASTM, Vibration Massage or Light Hand Massage. Proprioception changes were not statistically significant either within or between groups. Further evaluation of those interventions in a larger population with hamstrings pathology is required.

Effects of low-level laser therapy on hamstring strain injury rehabilitation: A randomized controlled trial

OBJECTIVES

To evaluate the effects of low-level laser therapy (LLLT) on functional rehabilitation following hamstring strain injury (HSI) in amateur athletes treated with an exercise-based rehabilitation program.

DESIGN

Randomized controlled trial.

METHODS

Male athletes (18-40 years old) who sustained HSI were randomized in LLLT or placebo groups. All patients were engaged in the same exercise-based rehabilitation program until they met specific criteria to return to sport. Hamstring muscles were treated with LLLT or placebo immediately after each rehabilitation session. The primary outcome was time-to-return to sport. Secondary outcomes were the number of rehabilitation sessions, hamstring flexibility, hamstring strength, and re-injury rate.

RESULTS

Twenty-four athletes began rehabilitation, and 22 (11 per group) completed the study schedule. Participants of LLLT and placebo groups had similar age, body size, injury characteristics, and baseline levels of hamstring flexibility and strength. The two groups increased flexibility and strength similarly throughout the rehabilitation program. Time-to-return to sport was the same for athletes treated with LLLT (23 ± 9 days) and placebo (24 ± 13 days). There were no re-injuries within 6 months after return to sport.

CONCLUSION

LLLT, as used in this study, did not optimize functional rehabilitation following HSI in amateur athletes treated with an exercise-based rehabilitation program.

Validity of an On-Field Readaptation Program Following a Hamstring Injury in Professional Soccer

Context: Despite the presence of various injury prevention programs, the rate of hamstring injuries and reinjuries is increasing in soccer, warranting the need for a soccer-specific rehabilitation program. Objective: To develop and validate a new, functional on-field program for the rehabilitation and readaptation of soccer players after a hamstring strain injury through a panel of experts; and determine the usefulness of the program through its application in professional soccer players. Design: A 13-item program was developed, which was validated by a panel of experts and later applied to professional soccer players. Setting: Soccer training ground. Participants: Fifteen strength and conditioning and rehabilitation fitness coaches with a professional experience of 15.40 (1.57) years in elite clubs and national teams in Europe validated the program. The program was later applied to 19 professional soccer players of the Spanish First Division (La Liga). Interventions: Once a player sustained a clinically diagnosed injury, the player would first be subject to mobilization and strengthening exercises in the gym after undergoing treatment by percutaneous needle electrolysis. The player would then complete an on-field readaptation program consisting of 13 drills arranged in a progressive manner in terms of complexity. The drills integrated various aspects of repeated sprint abilities, retraining and reeducation of biomechanical patterns, and neuromuscular control of the core and lower limbs. Main Outcome Measures: Aiken’s V for each item of the program and number of days taken by the players to return to play. Results: The experts evaluated all items of the program very highly, as seen from Aiken’s V values between 0.78 and 0.98 (0.63–0.99) for all drills, while the return to play was in 22.42 (2.32) days. Conclusion: This program has the potential to help a player suffering from a hamstring strain injury to adapt to real-match conditions in the readaptation phase through the application of sports-specific drills that were very similar to the different injury mechanisms.