Paula C. Charlton

Injuries impair the chance of successful performance by sportspeople: a systematic review

Background Cost–benefit analyses have been proposed for determining acceptable risk of injury regarding training and competition participation. Currently, there is no best evidence synthesis of the literature evaluating the relationship between injury/illness and chance of success or failure. Objective To evaluate the relationship between injury and/or illness and success and/or failure in athletic populations (individual and team sports). Methods This review was prospectively registered (PROSPERO CRD42016036729) and a systematic electronic search was conducted in May 2016. Inclusion criterion was any study design describing the association between injury and/or illness and success or failure in athletic performance. Two independent authors screened search results, performed data extraction and assessed methodological quality and strength of evidence using a modified Downs and Black appraisal tool and a modified van Tulder method, respectively. Results Of 10 546 titles identified, 14 satisfied the inclusion criteria and 7 had low risk of bias. Outcome measures associated with success and/or failure included: (1) availability of team members, (2) injury incidence, (3) injury burden, (4) squad utilisation and (5, 6) precompetition and in-competition injury. There was strong evidence that (1) increased availability of team members/athletes decreased the risk of failure and (2) precompetition and in-competition injuries were associated with increased risk of failure. Conclusions Injuries have a detrimental impact on team and individual athletic success. Increased player availability improves chances of success. Conversely, injuries sustained both prior to and during competition may increase risk of failure. Injury prevention should therefore be a priority for maximising athletic performance.

Single-Leg Squat Performance is Impaired 1 to 2 Years After Hip Arthroscopy.

To evaluate single‐leg squat performance 1‐2 years after arthroscopy for intra‐articular hip pathology compared with control subjects and the nonsurgical limb, and to investigate whether single‐leg squat performance on the operated limb was associated with hip muscle strength.

A simple method for quantifying jump loads in volleyball athletes

OBJECTIVES Evaluate the validity of a commercially available wearable device, the Vert, for measuring vertical displacement and jump count in volleyball athletes. Propose a potential method of quantifying external load during training and match play within this population. DESIGN Validation study. METHODS The ability of the Vert device to measure vertical displacement in male, junior elite volleyball athletes was assessed against reference standard laboratory motion analysis. The ability of the Vert device to count jumps during training and match-play was assessed via comparison with retrospective video analysis to determine precision and recall. A method of quantifying external load, known as the load index (LdIx) algorithm was proposed using the product of the jump count and average kinetic energy. RESULTS Correlation between two separate Vert devices and three-dimensional trajectory data were good to excellent for all jump types performed (r=0.83-0.97), with a mean bias of between 3.57-4.28cm. When matched against jumps identified through video analysis, the Vert demonstrated excellent precision (0.995-1.000) evidenced by a low number of false positives. The number of false negatives identified with the Vert was higher resulting in lower recall values (0.814-0.930). CONCLUSIONS The Vert is a commercially available tool that has potential for measuring vertical displacement and jump count in elite junior volleyball athletes without the need for time-consuming analysis and bespoke software. Subsequently, allowing the collected data to better quantify load using the proposed algorithm (LdIx).

Who ‘owns’ the injury or illness? Who ‘owns’ performance? Applying systems thinking to integrate health and performance in elite sport

Systems thinking frameworks have gained attention in both modelling athlete performance and injury prevention in sports medicine.1–3 We believe that these fields may contribute valuably and interdependently within a larger high performance system.1 The purpose of this editorial is to explain how ‘injury’ and ‘performance’ interact within a system-based framework3 and to provide three practical implications of an integrated performance system. The basic premise underpinning any systems model is that parts of a system are inter-related, and the objective of the whole system defines the function of each part. Therefore, the interaction between parts cannot be reduced to a number of linear cause and effect relations.1 The influence of a part on the outcome of the whole system depends on the state of the other parts. Any change to a part of the system can affect the objectives of the whole system as …

The reliability of a maximal isometric hip strength and simultaneous surface EMG screening protocol in elite, junior rugby league athletes

OBJECTIVES Firstly to describe the reliability of assessing maximal isometric strength of the hip abductor and adductor musculature using a hand held dynamometry (HHD) protocol with simultaneous wireless surface electromyographic (sEMG) evaluation of the gluteus medius (GM) and adductor longus (AL). Secondly, to describe the correlation between isometric strength recorded with the HHD protocol and a laboratory standard isokinetic device. DESIGN Reliability and correlational study. METHODS A sample of 24 elite, male, junior, rugby league athletes, age 16-20 years participated in repeated HHD and isometric Kin-Com (KC) strength testing with simultaneous sEMG assessment, on average (range) 6 (5-7) days apart by a single assessor. Strength tests included; unilateral hip abduction (ABD) and adduction (ADD) and bilateral ADD assessed with squeeze (SQ) tests in 0 and 45° of hip flexion. RESULTS HHD demonstrated good to excellent inter-session reliability for all outcome measures (ICC(2,1)=0.76-0.91) and good to excellent association with the laboratory reference KC (ICC(2,1)=0.80-0.88). Whilst intra-session, inter-trial reliability of EMG activation and co-activation outcome measures ranged from moderate to excellent (ICC(2,1)=0.70-0.94), inter-session reliability was poor (all ICC(2,1)<0.50). CONCLUSIONS Isometric strength testing of the hip ABD and ADD musculature using HHD may be measured reliably in elite, junior rugby league athletes. Due to the poor inter-session reliability of sEMG measures, it is not recommended for athlete screening purposes if using the techniques implemented in this study.

Exercise Interventions for the Prevention and Treatment of Groin Pain and Injury in Athletes: A Critical and Systematic Review

BackgroundGroin injury is a common musculoskeletal complaint for athletes competing in a variety of sports. The extent to which exercise interventions incorporating external load are an appropriate option for the treatment and prevention of groin injury in athletes is not yet clear.ObjectivesThe aim of this review was to describe and evaluate exercise therapy interventions and outcomes for the treatment and prevention of groin injury with specific attention to application of external load.Data SourcesThe databases Medline, PubMed, SPORTDiscus, Web of Science, and Cochrane were searched on 18 April 2016.Study Eligibility CriteriaThis review was registered as PROSPERO CRD42016037752 and a systematic search was conducted with the following inclusion criteria: any study design evaluating exercise interventions for the prevention or treatment of groin pain in athletes.Data AnalysisTwo independent authors screened search results, performed data extraction, assessed risk of bias using the modified Downs and Black appraisal tool and determined strength and level of evidence. Reporting standards for exercise interventions were assessed using the Consensus for Exercise Reporting Template (CERT).ResultsA total of 1320 titles were identified with 14 studies satisfying the inclusion criteria, four (29%) of which demonstrated low risk of bias. Ten (71%) studies utilised external load as a component of the exercise intervention. Reporting standards for exercise intervention scores ranged from 0 to 63%.ConclusionThere is limited evidence from level 2 and 3 studies indicating exercise therapy may reduce the incidence and hazard risk of sustaining a groin injury in athletes. There is strong evidence from level 4 studies indicating exercise therapy is beneficial as a treatment for groin injury in athletes in terms of symptom remission, return to sport and recurrence outcomes. However, there are limited studies with low risk of bias, and exercise interventions for the treatment of groin injury are poorly described.

Knee flexion not hip extension strength is persistently reduced following hamstring strain injury in Australian Football athletes: Implications for Periodic Health Examinations

OBJECTIVES Determine whether clinically feasible tests of isometric lower limb strength and range of motion (ROM) in Australian Football (AF) athletes are useful in Periodic Health Examinations to identify persistent deficits following hamstring strain injury (HSI). DESIGN Case-control. METHODS Thirty-seven male, semi-professional AF athletes (mean±SD; age, 20.2±2.9years; height, 1.7±0.5m; mass, 81±9.2kg) participated, ten athletes (37%) reported HSI within the previous three seasons of competition. Comparisons of pre-season isometric knee flexion and hip extension strength variables (peak force, torque and torque normalised to body mass) and hip, knee and ankle ROM measures were made between athletes with and without past-history of HSI using linear mixed-effect models. A logistic regression evaluated whether any of the outcome measures could differentiate athletes with a past-history of HSI. RESULTS Knee flexion peak force, torque and torque normalised to body mass were significantly reduced in athletes with a past-history of HSI (coefficient, 95% CI) (-44.8N, -86.3 to -3.3), (-22.2Nm, -40.5 to -3.7) and (-0.2Nmkg-1, -0.4 to 0.0) respectively. Knee flexion peak torque normalised to body mass (Nmkg-1) approached significance as a test was able to differentiate athletes with history of HSI (p=0.068). There were no differences between groups for any hip extension strength or lower limb ROM outcome measures. CONCLUSIONS Deficits in isometric peak knee flexion strength persist for up to three seasons following HSI in AF athletes. Isometric knee flexion strength testing may be a clinically feasible option for Periodic Health Examinations and inform tertiary injury prevention strategies.

Full training but not full function: Isometric hamstring strength deficits identified up to three years following injury in Australian Football athletes

Introduction: Reduced pre-season measures of concentric and eccentric hamstring strength have been identified as risk factors for future hamstring injury in soccer and Australian Football. The subsequent implementation of eccentric strength interventions has been shown to modulate this risk. However, the use of standalone pre-season assessments to predict future injury have been questioned with screening now advocated for the identification of existing and persisting deficits which may limit current sports participation. This concept is defined as tertiary prevention – assessments and interventions aimed at identification of persisting deficits following injury which may result in future complications such as recurrence or subsequent injury. The aim of this study was to use a simple and inexpensive method to evaluate unilateral isometric hamstring strength in Australian Football athletes with and without a past-history of hamstring muscle injury sustained within the previous three seasons. This information may inform the implementation of tertiary prevention strategies. Methods: This case-control study recruited 37 male semiprofessional Australian Football athletes (mean ± SD; age, 20.2 ± 2.9 y; height, 1.7 ± 0.5 m; mass, 81 ± 9.2 kg), 10 (27%) of which reported a past-history of hamstring muscle strain injury between 1 and 3 competitive seasons prior. All participants had been fully training for a minimum of one month prior to testing which was conducted during the pre-season, one week prior to the commencement of the season proper. Following collection of injury history and anthropometric data (height, mass, lever length) athletes underwent externally fixated maximal voluntary isometric knee flexion strength assessment using a previously published protocol with established reliability. A backwards stepwise linear mixed model was applied to compare athletes with a without a past-history of hamstring injury. Results: Peak isometric knee flexion force, torque and torque normalised to body mass were all significantly reduced in athletes who reported a past-history of hamstring muscle injury (coefficient, 95% CI) (−44.8 N, −86.3 to −3.3 N), (−22.2 Nm, −40.5 to −3.7 Nm) and (−0.2 Nm kg−1, −0.4 to 0.0 Nm kg−1) respectively. Knee flexion peak torque normalised to body mass approached significance as a test able to differentiate athletes with a history of HSI (p = 0.068). Discussion: Semi-professional Australian Football athletes who had sustained a hamstring muscle injury between one and three seasons prior to testing demonstrated significantly reduced hamstring strength. These deficits were evident despite full participation in training. Evaluation of unilateral isometric hamstring strength using these methods is a clinically feasible option that may be used to inform tertiary prevention strategies.