Hamstring and Ankle Flexibility Deficits Are Weak Risk Factors for Hamstring Injury in Professional Soccer Players: A Prospective Cohort Study of 438 Players Including 78 Injuries

The Acute: Chronic Workload Ratio and Injury Risk in Semiprofessional Football Players

The purpose of this study was to analyze the association and predictive capacity between the acute:chronic workload ratio (ACWR) and non-contact injuries in a semiprofessional football team. Seventeen football or soccer players from a Spanish Third Division football team participated voluntarily in this study. A prospective longitudinal study was developed during the 2020/2021 season. Twenty-four weeks were analyzed from October to March, including a regenerative microcycle due to the absence of competition during Christmas. Rate of perceived exertion (RPE) and session-rate of perceived exertion (sRPE) were registered for every training and game session. Afterward, acute and chronic workloads were calculated, and ACWR was subsequently derived from them. Furthermore, non-contact injuries were registered during the period mentioned. The main findings were that there is a poor correlation between the ACWR and non-contact injuries (r=0.069 (p<0.05)), and the use of the ACWR by itself is insufficient to predict the occurrence of non-contact injuries in a semiprofessional football team. Consequently, the ACWR is not an useful predictive tool for injuries in semiprofessional football teams.

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

CONTEXT

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

OBJECTIVE

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

DESIGN

Cross-sectional study.

SETTING

Major League Baseball via an online survey.

PATIENTS OR OTHER PARTICIPANTS

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

DATA COLLECTION AND ANALYSIS

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

RESULTS

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

CONCLUSIONS

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

A musculoskeletal multifactorial individualised programme for hamstring muscle injury risk reduction in professional football: results of a prospective cohort study

Objective

To test whether a musculoskeletal multifactorial and individualised hamstring muscle injury (HMI) risk reduction programme could reduce HMI risk in professional football.

Methods

We conducted a prospective cohort study in Finnish premier football league teams, with the 2019 season used as a control and an intervention conducted in the 2021 season. Screening was conducted to provide individualised programmes and monitor progress. Cox regression with hazard ratio (HR) was used with HMI as outcome and season as explanatory variable, including all players for primary analysis and those who performed the two seasons for secondary analysis.

Results

90 players were included in the control and 87 in the intervention seasons; 31 players performed in the 2 seasons. Twenty HMIs were recorded during the control and 16 during the intervention seasons. Cox regression analyses revealed that HMI risk at any given time was not significantly different between control and intervention seasons (for all players: HR 0.77 (95% CI 0.39 to 1.51), p=0.444; for the 31 players: HR 0.32 (95% CI 0.01 to 1.29), p=0.110)). For the 31 players, the HMI burden was significantly reduced in the intervention compared with the control season (RR 0.67 (95% CI 0.53 to 0.85)). Higher compliance with knee strength training, maximal velocity exposure and lower performance reductions in maximal theoretical horizontal force and knee flexor force were associated with lower HMI incidence.

Conclusions

Although the primary analysis did not reveal any significant effect of the intervention to reduce HMI risk in professional football, the programme was feasible, and additional secondary analyses showed a significant association between the intervention and lower HMI burden, incidence and risk.

Relationship between muscular extensibility, strength and stability and the transmission of impacts during fatigued running

The aim was to analyse the relationship between isokinetic strength, dynamic stability, muscular extensibility and impacts transmission during fatigued running. Low- and high-frequency impacts-related to body movements and the severity of impacts, respectively-were assessed in 17 male recreational runners, before and after a treadmill running fatigue protocol, using a triaxial accelerometry system. High-frequency impacts in the tibia were negatively correlated to the knee angle at which the quadriceps peak torque was reached (p = 0.014), and also to the extensibility of the hamstrings and soleus (p = 0.001 and p = 0.023, respectively). The increases of high-frequency impacts in tibia caused by fatigue were positively related to the knee angle at which the hamstrings peak torque was reached (p = 0.001) and to stability after landing (p = 0.007). The attenuation of high-frequency impacts was positively related to hamstrings/quadriceps ratio of strength (p = 0.010) and to stability (p = 0.006). Limiting possible deficits in hamstring and soleus range of motion, improving stability after landing, developing hamstring and quadriceps strength in elongated muscle range, and maintaining a balanced ratio of hamstring/quadriceps strength could help to reduce the injury risk in running.

Does Restricted Ankle Joint Mobility Influence Hamstring Muscle Strength, Work and Power in Football Players after ACL Reconstruction and Non-Injured Players?

This study was aimed at observing how the limitation of ankle dorsiflexion ROM affects hamstring muscle Peak Torque/BW (%), Average Power (W), and Total Work (J), and whether this effect is similar in football players after ACL rupture and reconstruction and in those without injuries. The study included 47 professional football players who were divided into two groups: Group 1 (n = 24) after ACL reconstruction and Group 2 (n = 23) without injuries in the past 3 years. Based on the Weight-Bearing Lunge Test (WBLT), the following subgroups in Groups 1 and 2 were distinguished: N (normal ankle joint dorsiflexion) and R (restricted ankle joint dorsiflexion). The concentric isokinetic test (10 knee flexions and extensions at 60°/s) was performed on both limbs. Significantly lower values of Peak Torque/BW and Average Power were observed in Group 1 compared to Group 2, as well as in subjects with normal and restricted ankle dorsiflexion. However, no significant differences were noted for either group in any of the strength variables comparing subjects with normal and restricted ankle dorsiflexion. A poor and non-significant correlation was exhibited between the ankle joint range of dorsiflexion and all the strength variables. The area under the ROC curve (AUC) for all the evaluated variables in both groups was below 0.5, or very close to this value, indicating that ankle dorsiflexion ROM has no diagnostic accuracy for hamstring muscle strength. Based on the obtained results, it can be assumed that ankle dorsiflexion limitation, which is common in football players, is not a factor in weakening hamstring muscle strength, either in football players after ACL reconstruction or among those without injuries. However, some authors have reported that limited mobility of the ankle joint can have a destructive effect on the work of the lower limbs and may also be a factor in increasing the risk of football injuries in this area. Therefore, we have suggested that hamstring muscle weakness and increased risk of injury may occur due to factors other than limited ankle mobility. These observations may be of great importance in the selection of prevention methods by including a broad spectrum of physical techniques, not just exercises that focus on the improvement of mobility or stability of the lower limbs.

Impact of COVID-19 lockdown on injury risk in Qatar's professional football

OBJECTIVES

To compare injury incidence, burden and characteristics between the pre- and post-COVID-19 lockdown periods in Qatari professional football.

DESIGN

Prospective cohort study.

METHODS

Injury and exposure data for two post-COVID-19 lockdown periods [early post-lockdown period: short-term ~2 months (54 matches) and late post-lockdown period: long-term 8-months (183 matches)] were compared to the benchmark of the same periods from the three previous seasons (2017/18-2019/20).

RESULTS

We observed no difference in overall, training or match incidence between early post-lockdown period and the benchmark reference. However, this short-term period resulted in lower burden for overall- (RR 0.80, P < 0.0001), training- (RR 0.73, P < 0.0001) and match-injuries (RR 0.40, P < 0.0001) compared to the benchmark. During late post-lockdown period match injury incidence (RR 0.72, P = 0.0010) and match injury burden (RR 0.69, P < 0.001) were lower than the benchmark. In contrast, both overall- (RR 1.30, P < 0.001) and training-injury burden (RR 1.65, P < 0.001) were higher. A significant increase in adductor strains in both post-lockdown periods was observed.

CONCLUSIONS

Immediately after the COVID-19 lockdown (short-term effect), there was no difference in injury incidence but a lower injury burden compared to benchmark. Moreover, the rapid return to competition for the successive season (long-term effect) was associated with a higher overall- and training-injury burden, but a lower match-injury burden compared to the benchmark.

Risk factors associated with football injury among male players from a specific academy in Ghana: a pilot study

There seems to be no information on the incidence of injury and associated risk factors for academy football players in Ghana. We determine the risk factors associated with match and training injuries among male football players at an academy in Ghana. Preseason measurements of players' height, weight, and ankle dorsiflexion (DF) range of motion (ROM) were measured with a stadiometer (Seca 213), a digital weighing scale (Omron HN-289), and tape measure, respectively. The functional ankle instability (FAI) of players was measured using the Cumberland Ankle Instability Tool (CAIT), and dynamic postural control was measured with the Star Excursion Balance Test. Injury surveillance data for all injuries were collected by resident physiotherapists throughout one season. Selected factors associated with injury incidence were tested using Spearman's rank correlation at a 5% significance level. Age was negatively associated with overall injury incidence (r = - 0.589, p = 0.000), match (r = - 0.294, p = 0.008), and training incidence (r = - 0.314, p = 0.005). Previous injury of U18s was associated with training injuries (r = 0.436, p = 0.023). Body mass index (BMI) was negatively associated with overall injury incidence (r = - 0.513, p = 0.000), and training incidence (r = - 0.395, p = 0.000). CAIT scores were associated with overall injury incidence (n = 0.263, p = 0.019) and match incidence (r = 0.263, p = 0.029). The goalkeeper position was associated with match incidence (r = 0.241, p = 0.031) while the U16 attacker position was associated with training incidence. Exposure hours was negatively associated with overall injury incidence (r = - 0.599, p = 0.000). Age, BMI, previous injury, goalkeeper and attacker positions, ankle DF ROM, and self-reported FAI were associated with injury incidence among academy football players in Ghana.

Effects of different intermittent pneumatic compression stimuli on ankle dorsiflexion range of motion

Despite substantial evidence of the effectiveness of intermittent pneumatic compression (IPC) treatments for range of motion (ROM) improvement, little evidence is available regarding how different IPC stimuli affect ankle dorsiflexion (DF) ROM. This study aimed to investigate the effects of different IPC stimuli on the ankle DF ROM. Fourteen, university intermittent team sport male athletes (age: 21 ± 1 year, height: 1.74 ± 0.05 m, body mass: 70.9 ± 7.7 kg, body fat percentage: 14.2 ± 3.6%, body mass index: 23.5 ± 2.5 kg/m²; mean ± standard deviation) completed four experimental trials in a random order: 1) no compression with wearing IPC devices (SHAM), 2) the sequential compression at approximately 80 mmHg (SQUEE80), 3) the uniform compression at approximately 80 mmHg (BOOST80), and 4) the uniform compression at approximately 135 mmHg (BOOST135). For the experimental trials, the participants were initially at rest for 10 min and then assigned to either a 30-min SHAM, SQUEE80, BOOST80, or BOOST135. Participants rested for 20 min after IPC treatment. The Weight-Bearing Lunge Test (WBLT), popliteal artery blood flow, pressure-to-pain threshold (PPT), muscle hardness, heart rate variability, and perceived relaxation were measured before (Pre) and immediately after IPC treatment (Post-0) and 20 min after IPC treatment (Post-20), and the changes in all variables from Pre (Δ) were calculated. ΔWBLT performance, ΔPPT, and Δperceived relaxation in all IPC treatments were significantly higher than those in SHAM at Post-0 and Post-20 (p < 0.05). ΔPopliteal artery blood flow in BOOST80 and BOOST135 was significantly higher than that in SHAM and SQUEE80 at Post-0 (p < 0.05). ΔMuscle hardness and Δheart rate variability did not differ significantly between trials. In conclusion, IPC treatments, irrespective of applied pressure and mode of compression, increased ankle DF ROM. This resulted from decreased pain sensitivity (i.e., increased PPT). In addition, high inflation pressure and frequency did not provide additional benefits in increasing ankle DF ROM.

High Number of Medical Conditions Detected in Elite Athlete Periodic Health Evaluations, But Only Mild Consequences

OBJECTIVE

To evaluate the number of medical conditions detected by periodic health evaluations (PHEs) in elite athletes, and their consequences for management and medical clearance.

DESIGN

Retrospective design.

PARTICIPANTS

Elite athletes of various sports in a high-performance program in The Netherlands, in the period between 2009 and 2020.

INTERVENTIONS

The PHEs consisted of a questionnaire, general and musculoskeletal physical examination, laboratory blood test, electrocardiogram, pulmonary function testing, and (cardiopulmonary) exercise test.

MAIN OUTCOME MEASURES

We extracted and analyzed the medical conditions that led to advice, clinical follow-up, further diagnostic investigation or treatment, and the medical clearance status of the athlete (clearance, temporarily no clearance, or permanently no clearance).

RESULTS

We included 721 PHEs of 451 elite athletes. We found 1389 medical conditions that led to advice (n = 923, 66%), clinical follow-up (n = 124, 9%), further diagnostic investigation (n = 190, 14%), treatment (n = 132, 10%), or sports restriction (n = 20, 1%). Only 20 cases (3%) led to temporarily no medical clearance. After further investigation or treatment, no permanent sports restriction was imposed on any of the athletes.

CONCLUSIONS

We found a high number of medical conditions detected with a PHE in elite athletes. However, the vast majority of detected conditions were mild, with consequences limited to preventive advice and follow-up. The yield of PHE to detect (potentially) severe pathological conditions seems low. Clinical relevance of PHE in elite athletes and potential future health benefits remain unclear.

Psychometric Properties of Four Common Clinical Tests for Assessing Hamstring Flexibility in Young Adults

Objective: To examine the psychometric properties of four common hamstring muscle flexibility tests involving the straight leg raise (SLR), passive knee extension (PKE), sit and reach test (SRT) and toe touch test (TTT) in young adults.

Methods: Forty-three young healthy adults (mean age 27.4 years) were recruited for 3 repeated sessions of hamstring flexibility assessments using the 4 tests mentioned above and the subsequent isokinetic examinations. The first two sessions (S1 and S2) were conducted by two different raters randomly on the first day (D1), and the third session (S3) was conducted by the same rater as S1 3 days later (D4). The next day (D5), the isokinetic performances of knee extensors and flexors of the dominant leg were assessed. To evaluate the interrater (S1 vs. S2) and test-retest (S1 vs. S3) reliability of hamstring flexibility tests, intraclass correlation coefficients (ICCs), standard errors of measurement, and the minimum detectable differences were calculated. Correlation analyses were performed to study the association of each hamstring flexibility test with the isokinetic muscle function of the knee flexors (H) and extensors (Q), including the peak torque (PT), total amount of work (TW) and average power (AP).

Results: Excellent interrater and test-retest reliability of hamstring flexibility tests involving the SLR, PKE, SRT and TTT were confirmed with ICCs ranging from 0.923 to 0.986. Fair correlations were found between the 4 hamstring flexibility tests and the H/Q for the PT at angular speeds of 180°/s (Pearson’s r at 0.330–0.449). In addition, the PKE was fairly correlated with the AP of the hamstring (Pearson’s r = 0.320) and the H/Q for the TW (Pearson’s r = 0.345) and AP (Pearson’s r = 0.386) at angular speeds of 180°/s.

Conclusions: This study confirmed that the SLR, PKE, SRT and TTT were reliable flexibility tests for hamstring muscles in young healthy adults, and the PKE might be a more valid outcome measure to predict hamstring injury.

Sex Differences in Pre-Season Anthropometric, Balance and Range-of-Motion Characteristics in Elite Youth Soccer Players

In soccer, injury epidemiology differs between males and females. It is clinically useful to know whether there are between-sex differences in selected characteristics relevant to primary injury risk and injury prevention practices. The purpose of this study was to explore between-sex differences in anthropometric, balance, and range-of-motion characteristics in Spanish elite male and female youth soccer players. This was a pre-season cross-sectional study. Sixty-nine males (age 16.8 ± 0.9 yr; height 175.9 ± 6.8 cm; mass 67.9 ± 6.3 kg) and thirty-seven females (age 17.2 ± 1.7 yr; height 164.0 ± 6.3 cm; mass 59.0 ± 5.8 kg) participated. Anthropometrics (standing/sitting height, bodymass, right/left leg length) and right/left anterior reach test (ART), hip internal/external active range of motion, active knee extension (AKE), and weightbearing lunge test (WBLT) were measured. Between-sex differences were assessed with Bonferroni-corrected Mann−Whitney U tests and Cliff’s delta (d). Between-sex significant differences (p < 0.003, d ≥ 0.50) were observed for anthropometric data and for hip internal rotation. No between-sex significant differences were observed for ART/AKE/WBLT measures. Between-sex significant differences with large effect sizes were identified for anthropometric data and right/left hip internal rotation. The present study adds new data to the literature for young Spanish male and female soccer players. The present findings will help inform clinical reasoning processes and future injury prevention research for elite male and female youth soccer players.

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

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

Hamstrings injuries in football

Background

Hamstrings injuries are a major concern in football (soccer), affecting both recreational players and professional athletes. Although being a recognized issue within the football community, its incidence has been increasing over the last years and still poses a challenge to all practitioners involved.

Study objectives and rationale

The goal of this narrative review is to outline hamstrings injuries epidemiology and mechanisms of injury, identify and discuss its risk factors, provide an approach to a proper early diagnosis, evaluate the efficacy of current treatment options and return to sports, and present the best strategies for hamstrings injury prevention. These guidelines will help the sports medicine staff team on how to better manage their players with or at risk of hamstrings injuries.

Conclusion

Despite several breakthroughs in research of hamstrings injuries, there is still heterogeneity across studies and lack of consensus in regards to classification, diagnosis, treatment and prevention. Hamstrings injuries compromise the athlete's performance with time loss due to injury, shortens their highest-level career longevity with higher risk of reinjury rates, and is a defying problem for clubs to balance financial losses due to having their players off the pitch. Further research is warranted to keep moving forward with evidence on treating and preventing hamstrings injuries to mitigate its high incidence and keep the players safe.

Hamstring Strain Injury Rehabilitation

Hamstring strain injuries are common among athletes and often require rehabilitation to prepare players for a timely return to sport performance while also minimizing reinjury risk. Return to sport is typically achieved within weeks of the injury; however, subsequent athlete performance may be impaired, and reinjury rates are high. Improving these outcomes requires rehabilitation practitioners (eg, athletic trainers and physical therapists) to understand the causes and mechanisms of hamstring strain injury, know how to perform a thorough clinical examination, and progress loading to the site of injury safely and effectively. This narrative review discusses current clinical concepts related to these aspects of rehabilitation for hamstring strain injury, with the aim of helping practitioners improve athletes' outcomes. Collectively, this knowledge will inform the implementation of evidence-based rehabilitation interventions.

Serial Within-Session Improvements in Ankle Dorsiflexion During Clinical Interventions Including Mobilization-With-Movement and A Novel Manipulation Intervention - A Case Series

BACKGROUND

Persisting reductions in ankle dorsiflexion range of motion are commonly encountered clinically and seen to be associated with adverse outcomes after ankle and other lower extremity injuries. Accordingly improving identified deficits is a common goal for rehabilitation; however, little data exists documenting any improvement related to interventions in these patients.

PURPOSE

To document the change in dorsiflexion range of motion after stretching and mobilization-with-movement and exercise and a novel manipulation intervention in a population of injured athletes.

DESIGN

Case series in 38 consecutive injured athletes with persisting reductions in ankle dorsiflexion range of motion (42 "stiff" ankles, 34 uninjured) in an outpatient sports physiotherapy clinic.

METHOD

During a single treatment session, two baseline measurements of weight-bearing dorsiflexion were taken at the start of the session to establish reliability and minimum detectable change, and then the same measures were performed after stretching and a mobilization-with-movement intervention, and again after clinical exercise and a novel manipulation which was applied on both ankles.

RESULTS

Excellent reliability was demonstrated (ICC2,1>0.93, MDC=3.5°) for the dorsiflexion measure. Statistically significant (p<0.01), but clinically meaningless improvements were seen after stretching and the mobilization-with-movement intervention on the injured and uninjured legs (1.9° and 1.4° respectively) with greater improvements seen after exercise and the subsequent manipulation (6.9° and 4.7°).

CONCLUSIONS

The relatively simple clinical exercise and manipulation intervention program was associated improvement in dorsiflexion range of motion in this cohort with persisting ankle stiffness. The interventions described largely restored range of motion consistent with baseline levels of the uninjured ankles. Improvements were also seen in the uninjured ankles following intervention.

Anthropometric and musculoskeletal gender differences in young soccer players

BACKGROUND

This study aimed to clarify potential gender differences across a comprehensive set of anthropometric and musculoskeletal characteristics within a young soccer player population.

METHODS

This study included 227 (121 males and 106 females with mean ages of 19.0 and 17.5 years, respectively) young elite soccer players. Anthropometric measurements were obtained. In addition, general joint laxity tests assessing the wrist, elbow, shoulder, trunk, hip, knee, and ankle were performed. Muscle flexibility tests were performed on the iliopsoas, quadriceps femoris, hamstring, gastrocnemius, and soleus muscles. Moreover, isometric knee extension and flexion strength and isometric hip abduction strength were measured. Single- and double-leg balance tests were also performed.

RESULTS

Male soccer players were taller, heavier, and had lower fat mass and percent body fat, and greater skeletal muscle mass and body minerals than female soccer players. Female soccer players had significantly greater laxity in all tests for general joint laxity. Female soccer players demonstrated significantly better hamstring and soleus flexibility than male soccer players but worse iliopsoas flexibility. Consequently, no significant differences were noticed in the quadriceps and gastrocnemius muscles between the male and female soccer players. However, female soccer players demonstrated significantly weaker knee extension and flexion and hip abduction. The hamstring- quadriceps ratio was significantly lower in female soccer players. Although no significant difference exists in the center of pressure excursion in the double-leg balance test between male and female soccer players, female soccer players displayed a significantly lower center of pressure excursion in the single-leg balance test.

CONCLUSIONS

Young male and female soccer players demonstrate significantly different anthropometric and musculoskeletal profiles.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Sprinting and hamstring strain injury: Beliefs and practices of professional physical performance coaches in Australian football

OBJECTIVES

The purpose of this study was to establish beliefs and practices of physical performance coaches regarding sprinting and Hamstring Strain Injury (HSI) in Australian Rules football.

DESIGNS

Delphi-validated questionnaire.

SETTING

Online.

PARTICIPANTS

Eighteen high-performance managers of the Australian Football League.

MAIN OUTCOME MEASURES

Descriptive statistics were collected to establish experience; central themes were established for the analyses of the beliefs and practices.

RESULTS

Nine (50%) physical performance coaches responded to an invitation to complete the questionnaire. Participants held an undergraduate degree and had 9.2 ± 4.3 years of experience. Accelerations (n = 9), maximum speed sprints (n = 9) and running with hip flexion (n = 7) were the most common activities associated with HSI. Coaches believed sprinting, eccentric strength training and proper periodisation were effective strategies to reduce HSI risk. There's a disparity between beliefs and practices when using GPS to monitor sprinting, however, all coaches reported regular exposure to sprint training across both pre and in-season. Overstriding (n = 9) and pelvic instability (n = 6) were identified as key flaws in running mechanics.

CONCLUSIONS

This information can be used to improve training strategies, whilst these findings indicate further investigations into sprint training and running mechanics for HSI risk reduction.

The Acute Effects of Cognitive-Based Neuromuscular Training and Game-Based Training on the Dynamic Balance and Speed Performance of Healthy Young Soccer Players: A Randomized Controlled Trial

Objective: The aim of this study was to investigate the acute effects of cognitive and game-based trainings (GBT) on dynamic balance (DB) and speed performance (SP) in healthy young soccer players. Materials and Methods: Forty-nine male soccer players were divided into three groups: cognitive-based neuromuscular training (CBNT; n = 16; age = 16.93 ± 1.18 years; body mass index [BMI] = 21.37 ± 1.57 kg/m²) group, GBT (n = 17; age = 17.05 ± 1.39 years; BMI = 21.10 ± 0.97 kg/m²) group, and control group (n = 16; age = 16.75 ± 1.12 years; BMI = 21.95 ± 1.36 kg/m²). The athletes in CBNT and GBT groups took part in one session lasting 1 hour. The Star Excursion Balance Test and the Speed Dribbling Test were used to evaluate DB and SP, respectively. The measurements were taken just before and after the trainings. Statistical analysis of the study was performed using SPSS 22.0 software (Statistical Package for Social Sciences, Inc., Chicago, IL). The Paired Student's t-test and Wilcoxon test were used. For in-group evaluation the ANOVA test was used for comparisons between the three groups. The Tukey's test was used for post hoc analysis. Results: DB significantly improved in all directions in the GBT group (P < 0.05). Also, significant improvements were observed in DB in all directions except anterior, anterolateral, and anteromedial in the CBNT group, and except anterior, medial, and anteromedial directons in the control group (P < 0.05). SP significantly developed just in the CBNT and GBT groups (P = 0.001, P = 0.003, respectively). CBNT and GBT improved the DB of soccer players by 9.6% and 9.5%, respectively. Also, trainings improved the SP by 3.1% and 2.6%, respectively. Conclusion: CBNT and GBT are promising trainings that can improve DB and SP of healthy young soccer players. Trial number: NCT03739658 (ClinicalTrials.gov Identifier).

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

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

Ultrasound-Guided Percutaneous Needle Electrolysis and Rehab and Reconditioning Program for Rectus Femoris Muscle Injuries: A Cohort Study with Professional Soccer Players and a 20-Week Follow-Up

Rectus femoris muscle strains are one of the most common injuries occurring in sports such as soccer. The purpose of this study was to describe the safety and feasibility of a combination of percutaneous needle electrolysis (PNE) and a specific rehab and reconditioning program (RRP) following an injury to the rectus femoris in professional soccer players. Thirteen professional soccer players received PNE treatment 48 h after a grade II rectus femoris muscle injury, followed by a the RRP 24 h later. Assessment of recovery from injury was done by registering the days taken to return to train (RTT), return to play (RTP), and structural and functional progress of the injured muscle was registered through ultrasound imaging and match-GPS parameters. Also, adverse events and reinjuries were recorded in the follow up period of twenty weeks. The RTT registered was 15.62 ± 1.80 days and RTP was 20.15 ± 2.79 days. After fourteen days, the ultrasound image showed optimal repair. Match-GPS parameters were similar before and after injury. There were no relapses nor were any serious adverse effects reported during the 20-week follow-up after the RTP. A combination of PNE and a specific RRP facilitated a faster RTP in previously injured professional soccer players enabling them to sustain performance and avoid reinjuries.

Normative data for hip strength, flexibility and stiffness in male soccer athletes and effect of age and limb dominance

OBJECTIVE

The objective was to establish normative data for hip strength, flexibility, and stiffness in male soccer athletes and to investigate the effect of age and limb dominance on these variables.

DESIGN

Cross-sectional.

SETTING

Soccer team physical therapy department.

PARTICIPANTS

A total of 293 asymptomatic male soccer athletes were assessed. Elite youth players aged 15-17 years and professional adult players aged 18-29 years old.

MAIN OUTCOME MEASURES

Rectus femoris, iliopsoas, hamstring muscle flexibility, passive hip stiffness, and isometric hip strength were measured using a goniometer, inclinometer, and handheld dynamometer, respectively. Descriptive and mixed analyses of variance were used as statistical procedures.

RESULTS

The dominant limb had lower iliopsoas (P = 0.010) and rectus femoris (P = 0.003) flexibility and higher external rotators torque compared to the non-dominant limb (P = 0.006) in both age groups. In adult athletes, the dominant limb had lower hip stiffness than the non-dominant limb (P = 0.002). Adults had higher hip external rotator torque than younger athletes (P < 0.0001). No differences were observed for hamstrings flexibility and hip extensors torque.

CONCLUSION

This study provided normative data of hip strength, flexibility, and stiffness for youth and adult male soccer athletes. In addition, there were no clinically relevant inter-limb differences.

Recalibrating the risk of hamstring strain injury (HSI): A 2020 systematic review and meta-analysis of risk factors for index and recurrent hamstring strain injury in sport

OBJECTIVE

To systematically review risk factors for hamstring strain injury (HSI).

DESIGN

Systematic review update.

DATA SOURCES

Database searches: (1) inception to 2011 (original), and (2) 2011 to December 2018 (update). Citation tracking, manual reference and ahead of press searches.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies presenting prospective data evaluating factors associated with the risk of index and/or recurrent HSI.

METHOD

Search result screening and risk of bias assessment. A best evidence synthesis for each factor and meta-analysis, where possible, to determine the association with risk of HSI.

RESULTS

The 78 studies captured 8,319 total HSIs, including 967 recurrences, in 71,324 athletes. Older age (standardised mean difference=1.6, p=0.002), any history of HSI (risk ratio (RR)=2.7, p<0.001), a recent HSI (RR=4.8, p<0.001), previous anterior cruciate ligament (ACL) injury (RR=1.7, p=0.002) and previous calf strain injury (RR=1.5, p<0.001) were significant risk factors for HSI. From the best evidence synthesis, factors relating to sports performance and match play, running and hamstring strength were most consistently associated with HSI risk. The risk of recurrent HSI is best evaluated using clinical data and not the MRI characteristics of the index injury.

SUMMARY/CONCLUSION

Older age and a history of HSI are the strongest risk factors for HSI. Future research may be directed towards exploring the interaction of risk factors and how these relationships fluctuate over time given the occurrence of index and recurrent HSI in sport is multifactorial.

Lower Extremity Biomechanical Examination of Athletes

A comprehensive lower extremity examination is a critical examination component for any type of injury in an athlete but should also be part of a preseason or preventive care program. Identification and treatment of biomechanical abnormalities and association with evidence-based risk factors for lower extremity disorders can be incorporated to potentially reduce risk or prevent acute and chronic injuries.

No association between perceived exertion and session duration with hamstring injury occurrence in professional football

Training and competition loads have emerged as modifiable composite risk factors of non-contact injury. Hamstring strains are the most common injuries in football with substantial burden on the individual player and club. Nevertheless, robust evidence of a consistent load-hamstring injury relationship in professional football is lacking. Using available data from the Qatar Stars League over three competitive seasons, this study investigated the separate and combined effects of perceived exertion and session duration on hamstring injury occurrence in a sample of 30 outfield football players. Load variables were calculated into 7-day, 14-day, 21-day, 28-day periods of data, and week-to-week changes for average ratings of perceived exertion (RPE; au) score and session-RPE (s-RPE; session-duration  ×  score), plus the cumulative training and match minutes and s-RPE, respectively. Conditional logistic regression models estimated load-injury relationships per 2-within-subject standard deviation increments in each candidate variable. Associations were declared practically important based on the location of the confidence interval in relation to thresholds of 0.90 and 1.11 defining small beneficial and harmful effects, respectively. The uncertainty for the corrected odds ratios show that typically high within-subject increments in each candidate variable were not practically important for training- and match-related hamstring injury (95% confidence intervals range: 0.85 to 1.16). We found limited exploratory evidence regarding the value of perceived exertion and session duration as etiological factors of hamstring injury in Middle-East professional football. Monitoring remains valuable to inform player load management strategies, but our exploratory findings suggest its role for type-specific injury risk determination appears empirically unsupported.

Effects of basketball match-play on ankle dorsiflexion range of motion and vertical jump performance in semi-professional players

BACKGROUND

The aim of this study was to investigate the effects of basketball match-play on ankle dorsiflexion range of motion (ROM) and countermovement (CMJ) performance, and their association with internal match load.

METHODS

Thirty semi-professional basketball players participated in this study. Ankle dorsiflexion ROM and bilateral CMJ performance were evaluated before (pre-match) and immediately after match-play (post-match). In addition, ankle dorsiflexion ROM was measured 48 hours post-match. Furthermore, for each player, the ankle dorsiflexion ROM scores were categorized as normal or restricted according to previously reported reference values (>2 cm change from baseline pre-match to post-match and to 48 hours post-match).

RESULTS

Ankle dorsiflexion ROM was increased post-match from pre-match in dominant and non-dominant limbs (most likely small) and decreased 48 hours post-match (most likely moderate) compared with immediately post-match measures in both limbs. Approximately 20% of all players showed restricted ankle dorsiflexion ROM values 48 hours post-match. CMJ performance was higher post-match than pre-match.

CONCLUSIONS

Ankle dorsiflexion ROM is still reduced 48 h after a competitive basketball match in semi-professional basketball players. The implementation of specific recovery strategies aiming at minimizing a decrease in ankle dorsiflexion after a match might be considered to reduce the likelihood of ankle injury.

Lower limb musculoskeletal screening in elite female Australian football players

OBJECTIVE

To report physical characteristics of lower-limb strength, endurance, range of motion, balance, and pain during adductor squeeze in elite female Australian Football (AF) players, and to examine the effect of limb dominance, previous AF experience, age, and previous level of sports participation on these characteristics.

DESIGN

Cross-sectional study.

SETTING

Three elite AF clubs.

PARTICIPANTS

Eighty-five female players. All were aged ≥18, contracted for the 2018 season, and participated in pre-season training.

MAIN OUTCOME MEASURES

The physical characteristic assessments included; pain on adductor squeeze, weight-bearing lunge, side bridge, isometric hip abduction and adduction strength, and the modified star excursion balance test.

RESULTS

The adductor squeeze had low pain scores, with 93% of players scoring ≤2 on the numerical rating scale. Other assessment results were (mean ± SD): 10.8 ± 2.7 cm for weight-bearing lunge, 95 ± 39s for side bridge, 1.85 ± 0.23 and 1.85 ± 0.36Nm/kg for hip abduction and adduction strength respectively, and 92 ± 8% for the modified star excursion balance test. There was no clinically relevant effect of limb dominance, previous AF experience, age, or previous level of sports on physical characteristics.

CONCLUSIONS

Physical characteristics for five assessments are reported. These data can be used for comparison purposes in the screening and clinical management of elite female AF players.

Examination of Physical Characteristics and Positional Differences in Professional Soccer Players in Qatar

Physical characteristics in professional soccer differ between competition levels and playing positions, and normative data aid practitioners in profiling their players to optimize performance and reduce injury risk. Given the paucity of research in Arabic soccer populations, the purpose of this study was to provide position-specific normative values for professional players competing in the Qatar Stars League. One hundred and ninety-five players completed a musculoskeletal assessment as part of an annual periodic health examination. Tests included measures of range of motion (hip, ankle, and hamstring), bilateral and unilateral jump performance, and quadriceps/hamstring (isokinetic/NordBord), hip adduction/abduction (eccentric), and groin (isometric) strength. Descriptive data were examined, and positional differences were analyzed using a one-way analysis of variance (ANOVA). Goalkeepers were significantly heavier (p < 0.01), had a higher body mass index (p < 0.05) than outfield positions and demonstrated greater absolute strength. Defenders were the strongest relative to body mass, and these differences were significant (p < 0.05) versus goalkeepers and strikers. No meaningful between-group comparisons were apparent for jumping or range of motion tests. Compared to mean values from other professional leagues, soccer players in Qatar appear to be shorter, lighter and display inferior strength and jump capacities. These data can be used to tailor training and rehabilitation programs to the specifics of the league and position in which the athletes compete.