Effect of Data-Processing Methods on Acceleration Summary Metrics of GNSS Devices in Elite Australian Football.

This study aimed to measure the differences in commonly used summary acceleration metrics during elite Australian football games under three different data processing protocols (raw, custom-processed, manufacturer-processed). Estimates of distance, speed and acceleration were collected with a 10-Hz GNSS tracking technology device from fourteen matches of 38 elite Australian football players from one team. Raw and manufacturer-processed data were exported from respective proprietary software and two common summary acceleration metrics (number of efforts and distance within medium/high-intensity zone) were calculated for the three processing methods. To estimate the effect of the three different data processing methods on the summary metrics, linear mixed models were used. The main findings demonstrated that there were substantial differences between the three processing methods; the manufacturer-processed acceleration data had the lowest reported distance (up to 184 times lower) and efforts (up to 89 times lower), followed by the custom-processed distance (up to 3.3 times lower) and efforts (up to 4.3 times lower), where raw data had the highest reported distance and efforts. The results indicated that different processing methods changed the metric output and in turn alters the quantification of the demands of a sport (volume, intensity and frequency of the metrics). Coaches, practitioners and researchers need to understand that various processing methods alter the summary metrics of acceleration data. By being informed about how these metrics are affected by processing methods, they can better interpret the data available and effectively tailor their training programs to match the demands of competition.

Classification of Force-Time Metrics Into Lower-Body Strength Domains.

ABSTRACT: Geneau, MC, Carey, DL, Gastin, PB, Robertson, S, and James, LP. Classification of force-time metrics into lower-body strength domains. J Strength Cond Res 38(9): 1561-1567, 2024-The purpose of this study was to classify force-time metrics into distinct lower-body strength domains using a systematic data reduction analysis. A cross-sectional design was used, whereby competitive field sport athletes ( F = 39, M = 96) completed a series of drop jumps, squat jumps, countermovement jumps (CMJs), loaded CMJs, and 2 isometric tasks on portable force platforms, resulting in a total of 285 force-time performance metrics. The metrics were split into 4 test "families" and each was entered into a sparse principal component analysis (sPCA) model. A single metric from each component of each family-specific sPCA were selected based on the loading, reliability, and simplicity of the metric and entered into a second sPCA that included metrics across all tests. The final sPCA revealed 7 principal components each containing 2 metrics and explained a total of 53% variance of the dataset. The final principal components were interpreted as 7 lower-body strength domains: (a) dynamic force, (b) dynamic timing, (c) early isometric, (d) maximal isometric, (e) countermovement velocity, (f) reactive output, and (g) reactive timing. The findings demonstrate that a total of 7 metrics from a drop jump, CMJ, and isometric test can be used to represent ∼50% of variance in lower-body strength performance of field sport athletes. These results can help guide and simplify the lower-body strength diagnosis process in field sport athletes.

Discovery and Characterisation of Forward Line Formations at Centre Bounces in the Australian Football League.

The extent of player formation usage and the characteristics of player arrangements are not well understood in Australian football, unlike other team-based invasion sports. Using player location data from all centre bounces in the 2021 Australian Football League season; this study described the spatial characteristics and roles of players in the forward line. Summary metrics indicated that teams differed in how spread out their forward players were (deviation away from the goal-to-goal axis and convex hull area) but were similar with regard to the centroid of player locations. Cluster analysis, along with visual inspection of player densities, clearly showed the presence of different repeated structures or formations used by teams. Teams also differed in their choice of player role combinations in forward lines at centre bounces. New terminology was proposed to describe the characteristics of forward line formations used in professional Australian Football.

Association Between Position-Specific Impact and Movement Characteristics of Professional Rugby Union Players During Game Play.

ABSTRACT: Peek, RJ, Carey, DL, Middleton, KJ, Gastin, PB, and Clarke, AC. Association between position-specific impact and movement characteristics of professional rugby union players during game play. J Strength Cond Res 37(1): 161-166, 2023-The aim of this study was to understand the association between impact and movement characteristics during whole game and peak 1- to 10-minute rolling windows in professional rugby union. Maximal impact (impacts·min-1) and corresponding running (m·min-1) characteristics as well as maximal running (m·min-1) and corresponding impact (impacts·min-1) characteristics were obtained for 160 athletes from 4 teams across the 2018 and 2019 Super Rugby seasons. A linear mixed-effects model reported a positive association between whole-game running and impacts, where greater impact characteristics corresponded with greater running characteristics. The average 1-minute peak running characteristics (150-160 m·min-1) typically occurred when no impacts occurred. The average 1-minute peak impact characteristics (4-6 impacts·min-1) corresponded with an average relative distance of 90-100 m·min-1. Worst case scenario observed impact characteristics as large as 15 impacts·min-1 with a corresponding relative distance of 140 m·min-1. When training for peak period characteristics, running may be completed in isolation; however, peak impacts often occur in conjunction with moderate to high running movements. Given running and impact characteristics can appear concurrently within game play, this highlights the need to train them accordingly. As such, when prescribing training drills to replicate the peak characteristics in rugby union, consideration should be taken for both running and impact characteristics.

Peak movement and impact characteristics of different training methods in professional rugby union.

The purpose of this study was to compare the peak periods (1- to 6-minute epochs) for three different training methods (game-based training - GBT; small-sided games - SSG; and conditioning training - CT) in elite male rugby union (RU) players. The peak movement (m·min-1) and impact (impact·min-1) characteristics of 42 players during in-season training were assessed. When comparing between training methods, SSG drills produced the greatest peak movement characteristics for all time epochs (1-minute average peak periods - SSG 195 m·min-1, GBT 160 m·min-1, and CT 144 m·min-1). The peak impact characteristics performed during training were 1-2 impact·min-1 for a 1-minute period and then decreased as the time period increased for all training methods. The greatest distribution of training time occurred at 30-39% (SSG and CT) and 40-49% (GBT) of peak movement intensity, with less than 5% of training performed at or above 80% peak intensity across all drill types. Findings from the current study show that the peak movement periods (m·min-1) in RU training from all three training methods match or exceed those which are previously reported in peak gameplay, yet their ability to replicate peak impact characteristics is questionable.

Comparison of player-dependent and independent high-speed running thresholds to model injury risk in football.

High-speed running (HSR) loads have been linked with non-contact injury risks in team-sports. This study investigated whether player-specific speed zones, reflecting individual fitness characteristics, impact the associations between non-contact injury and acute and chronic HSR loads. Semi-professional soccer players from two clubs (n = 47) were tracked over two seasons using 10 Hz GPS (5552 observations). HSR distances were calculated arbitrarily (≥5.5 m·s-1), and in an individualised fashion based on the final speed of the 30-15 intermittent fitness test. Cumulative running loads were represented by exponentially weighted moving averages with 7-(acute) and 28-day (chronic) decay parameters. Physiotherapists collected non-contact, lower-limb, time-loss injury data (n = 101). Injury models using session type (training vs matches), coach, as well as arbitrary or individualised running loads were constructed via mixed-effect logistic regression. Session type had the largest effect on injury (training vs match OR = 0.28; 95%CI:0.17-0.44). Variations in individualised or arbitrary acute and chronic HSR loads within the mid-range of the observed data had negligible effects on predicted injury risk. However, the uncertainty of estimated effects at extreme values of acute and chronic HSR loads prevented any conclusive findings. Therefore, the efficacy of using customised speed thresholds in quantifying load for injury risk mitigation purposes remains unclear.

Load Centralization Does Not Affect the Kinetic and Kinematic Output of Countermovement Jumps.

ABSTRACT: Tredrea, MSJ, Middleton, KJ, Bourne, MN, Carey, DL, Scanlan, AT, and Dascombe, BJ. Load centralization does not affect the kinetic and kinematic output of countermovement jumps. J Strength Cond Res 36(4): 1084-1089, 2022-This study aimed to compare the kinetics, kinematics, and performance of countermovement jumps (CMJs) when completed with 2 different loading conditions (centralized or peripheral) across increasing loads. Seventeen subjects (12 men and 5 women) randomly completed 2 series of CMJs with increasing loads separated by a 30-minute rest period between conditions. Subjects were loaded with either a weighted vest (centralized) or straight barbell (peripheral). A randomized, counterbalanced crossover design was used with incremental loads of 10, 20, 30, 40, and 50% of body mass added to the vest or barbell. Measures of peak force, acceleration, velocity, and power were calculated across each subphase of the CMJs. No significant differences were observed in kinetic or kinematic variables between loading conditions. Within each condition there were significant reductions (p < 0.05) in peak concentric velocity and acceleration, as well as significant increases (p < 0.05) in peak force when the external load increased. Furthermore, braking and propulsive phase duration significantly increased (p < 0.05) and jump height significantly decreased (p < 0.05) as the external load increased. Countermovement jump performance was similar in both central and peripheral loading, whereas increasing load significantly affected jump height, force, velocity, and acceleration variables irrespective of load position. The training stimulus from an external load placed centrally or peripherally is similar regardless of where it is positioned; however, from a practical perspective, a weighted vest may provide a more mobile and safer alternative than a barbell.

A case of oral foreign-body granuloma due to diatoms.

Diatoms are photosynthetic algae with a siliceous exoskeleton. Diatoms are utilized by a wide array of industries for applications such as filtration and pest control. Unsubstantiated claims have also propelled their societal reach to trendy oral and topical uses. This case highlights a rare case of an oral granuloma secondary to diatoms. An 80-year-old woman presented with a mobile, firm, asymptomatic submucosal mass on her lower left mandibular vestibular mucosa. Histopathology showed a non-caseating granulomatous reaction to diatoms. Her only verified contact with a diatomaceous earth product was a dental impression using alginate after upper front teeth trauma 5 months before. Although there have been several cases of allergic contact dermatitis attributed to diatoms, there are no reported cases of diatom-induced granuloma formation found in the literature. There are, however, ample data on granulomas initiated by silica. Given the silica-based composition of diatoms, and the broad use of diatoms in industry and alternative medicine, it is unclear why diatom-induced granulomas are not more widely described. This report may alert clinicians to the existence of diatom granulomas and incline them to tailor their history to cover questions about possible exposure when evaluating patients presenting with a localized oral lesion.

Training loads and injury risk in Australian football-differing acute: chronic workload ratios influence match injury risk.

AIMS: (1) To investigate whether a daily acute:chronic workload ratio informs injury risk in Australian football players; (2) to identify which combination of workload variable, acute and chronic time window best explains injury likelihood. METHODS: Workload and injury data were collected from 53 athletes over 2 seasons in a professional Australian football club. Acute:chronic workload ratios were calculated daily for each athlete, and modelled against non-contact injury likelihood using a quadratic relationship. 6 workload variables, 8 acute time windows (2-9 days) and 7 chronic time windows (14-35 days) were considered (336 combinations). Each parameter combination was compared for injury likelihood fit (using R2). RESULTS: The ratio of moderate speed running workload (18-24 km/h) in the previous 3 days (acute time window) compared with the previous 21 days (chronic time window) best explained the injury likelihood in matches (R2=0.79) and in the immediate 2 or 5 days following matches (R2=0.76-0.82). The 3:21 acute:chronic workload ratio discriminated between high-risk and low-risk athletes (relative risk=1.98-2.43). Using the previous 6 days to calculate the acute workload time window yielded similar results. The choice of acute time window significantly influenced model performance and appeared to reflect the competition and training schedule. CONCLUSIONS: Daily workload ratios can inform injury risk in Australian football. Clinicians and conditioning coaches should consider the sport-specific schedule of competition and training when choosing acute and chronic time windows. For Australian football, the ratio of moderate speed running in a 3-day or 6-day acute time window and a 21-day chronic time window best explained injury risk.

A framework for test measurement selection in athlete physical preparation.

Preparing athletes for competition requires the diagnosis and monitoring of relevant physical qualities (e.g., strength, power, speed, endurance characteristics). Decisions regarding test selection that attempt to measure these physical attributes are fundamental to the training process yet are complicated by the myriad of tests and measurements available. This article presents an evidenced based process to inform test measurement selection for the physical preparation of athletes. We describe a method for incorporating multiple layers of validity to link test measurement to competition outcome. This is followed by a framework by which to evaluate the suitability of test measurements based on contemporary validity theory that considers technical, decision-making, and organisational factors. Example applications of the framework are described to demonstrate its utility in different settings. The systems presented here will assist in distilling the range of measurements available into those most likely to have the greatest impact on competition performance.

Trajectory of knee health in runners with and without heightened osteoarthritis risk: the TRAIL prospective cohort study protocol.

INTRODUCTION: Running is one of the most popular recreational activities worldwide, due to its low cost and accessibility. However, little is known about the impact of running on knee joint health in runners with and without a history of knee surgery. The primary aim of this longitudinal cohort study is to compare knee joint structural features on MRI and knee symptoms at baseline and 4-year follow-up in runners with and without a history of knee surgery. Secondary aims are to explore the relationships between training load exposures (volume and/or intensity) and changes in knee joint structure and symptoms over 4 years; explore the relationship between baseline running biomechanics, and changes in knee joint structure and symptoms over 4 years. In addition, we will explore whether additional variables confound, modify or mediate these associations, including sex, baseline lower-limb functional performance, knee muscle strength, psychological and sociodemographic factors. METHODS AND ANALYSIS: A convenience sample of at least 200 runners (sex/gender balanced) with (n=100) and without (n=100) a history of knee surgery will be recruited. Primary outcomes will be knee joint health (MRI) and knee symptoms (baseline; 4 years). Exposure variables for secondary outcomes include training load exposure, obtained daily throughout the study from wearable devices and three-dimensional running biomechanics (baseline). Additional variables include lower limb functional performance, knee extensor and flexor muscle strength, biomarkers, psychological and sociodemographic factors (baseline). Knowledge and beliefs about osteoarthritis will be obtained through predefined questions and semi-structured interviews with a subset of participants. Multivariable logistic and linear regression models, adjusting for potential confounding factors, will explore changes in knee joint structural features and symptoms, and the influence of potential modifiers and mediators. ETHICS AND DISSEMINATION: Approved by the La Trobe University Ethics Committee (HEC-19524). Findings will be disseminated to stakeholders, peer-review journals and conferences.

The temporal distribution and occurrence of impacts and movement relative to peak periods in men's rugby union.

OBJECTIVES: This study identifies the distribution (as a percentage of the positional peak) and occurrence (within a half) of 1-min movement characteristics (m·min-1) and contact-based events (impact·min-1) during professional rugby union game play. DESIGN: Within 95 rugby union games, players wore global positioning system (GPS) devices (n = 1422 player-game files, 160 athletes). One-minute rolling-window averages were calculated with the maximum and mean value being recorded for each dependent variable; relative distance (m·min-1) and impacts (impact·min-1), then standardised by the positional peak mean. METHODS: The distribution of these variables accumulated in 10% increments of the peak were determined as was their occurrence throughout a playing half for each positional group. RESULTS: The greatest distribution of game play (%) was observed at ~30-39% of the positional peak for movement and with no impacts. The greatest occurrence of maximum positional peak 1-min movement periods occurred at the beginning of each half and declined as the half went on. Peak impact characteristics, however, were found to be more sporadic across a half. CONCLUSIONS: These findings suggest that the distribution of positional peak 1-min movement (80-100%+) and peak impacts (4+) were <5% of overall game play, and observed <2% of total occurrences. This highlights that practitioners should alter training drills by time, volume, and intensity in order to replicate the peak intensities of game play.

Validity and between-unit agreement of commercially-available linear position transducer and inertial sensor devices during loaded countermovement jumps.

To assess the validity and between-unit agreement of velocity monitoring devices during incrementally-loaded countermovement jumps (CMJ), 16 males (24.0 ± 3.5 yr) completed 12 CMJs on a force plate (FP). Performance variables were collected through two linear position transducers (GymAware [GA]) and four accelerometer-based devices (two PUSH units, two Bar Sensei units). Pearson correlations (r) and coefficients of variation (CV) demonstrated strong to very-strong relationships (r = 0.60-0.88) and poor agreement (CV = 11.7-25.3%) between FP and GA, and moderate to very-strong relationships (r = 0.31-0.81) and poor agreement (CV = 10.1-24.2%) between FP and PUSH. Between-unit comparisons demonstrated moderate to very-strong relationships (r = 0.50-0.88) with poor agreement (CV = 10.8-26.6%) for GA, and very weak to very-strong relationships (r = 0.01-0.87) with moderate to poor agreement (CV = 9.1-24.1%) for PUSH. Bar Sensei units were excluded from analyses. Loaded CMJ data collected with either device displayed poor agreement with a FP. Velocity monitoring devices demonstrate poor validity across all loads; however, GA demonstrated strong between-unit agreement. A FP should be utilised to accurately assess CMJ performance at all times.

Predicting Youth Athlete Sleep Quality and the Development of a Translational Tool to Inform Practitioner Decision Making.

BACKGROUND: Identifying key variables that predict sleep quality in youth athletes allows practitioners to monitor the most parsimonious set of variables that can improve athlete buy-in and compliance for athlete self-report measurement. Translating these findings into a decision-making tool could facilitate practitioner willingness to monitor sleep in athletes. HYPOTHESIS: Key predictor variables, identified by feature reduction techniques, will lead to higher predictive accuracy in determining youth athletes with poor sleep quality. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 3. METHODS: A group (N = 115) of elite youth athletes completed questionnaires consisting of the Pittsburgh Sleep Quality Index and questions on sport participation, training, sleep environment, and sleep hygiene habits. A least absolute shrinkage and selection operator regression model was used for feature reduction and to select factors to train a feature-reduced sleep quality classification model. These were compared with a classification model utilizing the full feature set. RESULTS: Sport type, training before 8 am, training hours per week, presleep computer usage, presleep texting or calling, prebedtime reading, and during-sleep time checks on digital devices were identified as variables of greatest influence on sleep quality and used for the reduced feature set modeling. The reduced feature set model performed better (area under the curve, 0.80; sensitivity, 0.57; specificity, 0.80) than the full feature set models in classifying youth athlete sleep quality. CONCLUSION: The findings of our study highlight that sleep quality of elite youth athletes is best predicted by specific sport participation, training, and sleep hygiene habits. CLINICAL RELEVANCE: Education and interventions around the training and sleep hygiene factors that were identified to most influence the sleep quality of youth athletes could be prioritized to optimize their sleep characteristics. The developed sleep quality nomogram may be useful as a decision-making tool to improve sleep monitoring practice among practitioners.

In Professional Male Soccer Players, Time-Loss Groin Injury Is More Associated With the Team Played for Than With Training/Match-Play Duration.

OBJECTIVE: To investigate the relationship between training/match-play duration and time-loss groin injury in professional male soccer players, and to determine whether previously identified intrinsic risk factors influenced this relationship. DESIGN: Prospective cohort study. METHODS: A total of 579 professional male soccer players were prospectively followed from July 2013 to June 2015. Time-loss groin injuries and individual training and match-play duration were recorded using standardized surveillance methods. Acute training/match-play duration and chronic training/match-play duration were considered as interacting variables. Nonlinear Cox regression analysis (modeled using restricted cubic splines), clustered by player identification number, examined the relationship between training/match-play duration and groin injury. Previously identified intrinsic risk factors of previous groin injury and eccentric adduction strength were included in the multivariable regression analysis. RESULTS: There was no clinically meaningful relationship between training/match-play duration and groin injury risk. Team played for had the strongest influence on groin injury risk (relative log hazard ratio -2.28 to 0.97). Groin injury risk was highest when accumulated chronic and acute training duration was also highest, but large confidence intervals indicate considerable uncertainty around this finding. Previous groin injury and eccentric adduction strength were not associated with groin injury risk when training/match-play duration and team were included in the model. CONCLUSION: In professional male soccer players, there was no clinically meaningful relationship between groin injury risk and training/match-play duration. Team played for either protected against or increased groin injury risk, indicating that team-related factors not measured in this study had greater effect on groin injury risk than training/match-play duration. J Orthop Sports Phys Ther 2022;52(4):217-223. Epub 5 Feb 2022. doi:10.2519/jospt.2022.10845.

Dimensionality Reduction for Countermovement Jump Metrics.

PURPOSE: Dozens of variables can be derived from the countermovement jump (CMJ). However, this does not guarantee an increase in useful information because many of the variables are highly correlated. Furthermore, practitioners should seek to find the simplest solution to performance testing and reporting challenges. The purpose of this investigation was to show how to apply dimensionality reduction to CMJ data with a view to offer practitioners solutions to aid applications in high-performance settings. METHODS: The data were collected from 3 cohorts using 3 different devices. Dimensionality reduction was undertaken on the extracted variables by way of principal component analysis and maximum likelihood factor analysis. RESULTS: Over 90% of the variance in each CMJ data set could be explained in 3 or 4 principal components. Similarly, 2 to 3 factors could successfully explain the CMJ. CONCLUSIONS: The application of dimensional reduction through principal component analysis and factor analysis allowed for the identification of key variables that strongly contributed to distinct aspects of jump performance. Practitioners and scientists can consider the information derived from these procedures in several ways to streamline the transfer of CMJ test information.

Factors that Impact Self-reported Wellness Scores in Elite Australian Footballers.

INTRODUCTION: This study aimed to 1) identify the impact of external load variables on changes in wellness and 2) identify the impact of age, training/playing history, strength levels, and preseason loads on changes in wellness in elite Australian footballers. METHODS: Data were collected from one team (45 athletes) during the 2017 season. Self-reported wellness was collected daily (4, best score possible; 28, worst score possible). External load/session availability variables were calculated using global positioning systems and session availability data from every training session and match. Additional variables included demographic data, preseason external loads, and strength/power measures. Linear mixed models were built and compared using root mean square error (RMSE) to determine the impact of variables on wellness. RESULTS: The external load variables explained wellness to a large degree (RMSE = 1.55, 95% confidence intervals = 1.52 to 1.57). Modeling athlete ID as a random effect appeared to have the largest impact on wellness, improving the RMSE by 1.06 points. Aside from athlete ID, the variable that had the largest (albeit negligible) impact on wellness was sprint distance covered across preseason. Every additional 2.1 km covered across preseason worsened athletes' in-season wellness scores by 1.2 points (95% confidence intervals = 0.0-2.3). CONCLUSIONS: The isolated impact of the individual variables on wellness was negligible. However, after accounting for the individual athlete variability, the external load variables examined collectively were able to explain wellness to a large extent. These results validate the sensitivity of wellness to monitor individual athletes' responses to the external loads imposed on them.

Eccentric knee flexor weakness in elite female footballers 1-10 years following anterior cruciate ligament reconstruction.

OBJECTIVES: To determine eccentric knee flexor strength in elite female Australian Rules Football (ARF) players with and without a history of unilateral anterior cruciate ligament reconstruction (ACLR) using an ipsilateral semitendinosus graft. DESIGN: Case-control. SETTING: Elite ARF Women's competition. PARTICIPANTS: Eighty-four elite female ARF players (mean age, 25 ±â€¯4.9 years; height, 1.71 ±â€¯0.73 m; weight, 67 kg ±â€¯7.4 kg) with (n = 12) and without (n = 72) a history of unilateral ACLR in the previous 10 years. MAIN OUTCOME MEASURES: Peak eccentric knee flexor force during the Nordic hamstring exercise (NHE). RESULTS: Players with a history of unilateral ACLR displayed lower levels of eccentric knee flexor strength in their surgically reconstructed limb than their uninjured contralateral limb (mean difference -53.77 N, 95% CI = -85.06 to -24.27, d = -0.51) and compared to the limbs of players with no history of injury (mean difference = -46.32 N, 95% CI = -86.65 to -11.13, d = -0.73). CONCLUSION: Elite female ARF players with a history of unilateral ACLR display deficits in eccentric knee flexor strength in their surgically reconstructed limb for up to 10 years following surgery.

Session Availability as a Result of Prior Injury Impacts the Risk of Subsequent Non-contact Lower Limb Injury in Elite Male Australian Footballers.

Prior injury is a commonly identified risk factor for subsequent injury. However, a binary approach to classifying prior injury (i.e., yes/no) is commonly implemented and may constrain scientific findings, as it is possible that variations in the amount of time lost due to an injury will impact subsequent injury risk to differing degrees. Accordingly, this study investigated whether session availability, a surrogate marker of prior injury, influenced the risk of subsequent non-contact lower limb injury in Australian footballers. Data were collected from 62 male elite Australian footballers throughout the 2015, 2016, and 2017 Australian Football League seasons. Each athlete's participation status (i.e., full or missed/modified) and any injuries that occurred during training sessions/matches were recorded. As the focus of the current study was prior injury, any training sessions/matches that were missed due to reasons other than an injury (e.g., load management, illness and personal reasons) were removed from the data prior to all analyses. For every Monday during the in-season periods, session availability (%) in the prior 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, and 84 days was determined as the number of training sessions/matches fully completed (injury free) relative to the number of training sessions/matches possible in each window. Each variable was modeled using logistic regression to determine its impact on subsequent injury risk. Throughout the study period, 173 non-contact lower limb injuries that resulted in at least one missed/modified training session or match during the in-season periods occurred. Greater availability in the prior 7 days increased injury probabilities by up to 4.4%. The impact of session availability on subsequent injury risk diminished with expanding windows (i.e., availability in the prior 14 days through to the prior 84 days). Lesser availability in the prior 84 days increased injury probabilities by up to 14.1%, only when coupled with greater availability in the prior 7 days. Session availability may provide an informative marker of the impact of prior injury on subsequent injury risk and can be used by coaches and clinicians to guide the progression of training, particularly for athletes that are returning from long periods of 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 ±â€¯SD): 10.8 ±â€¯2.7 cm for weight-bearing lunge, 95 ±â€¯39s for side bridge, 1.85 ±â€¯0.23 and 1.85 ±â€¯0.36Nm/kg for hip abduction and adduction strength respectively, and 92 ±â€¯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.