Background
From an injury-prevention perspective, acute increase in training load has been identified as a known risk factor. The acute to chronic workload ratio (ACWR), defined as the most recent 7-day training load divided by the athlete’s monthly average, quantifies such spikes helps monitor training load. Unlike prior pooled multi sport studies, this study directly compares endurance and strength-based athletes to evaluate differences in ACWR distributions and injury patterns necessitating epidemiological description in mixed cohorts.
Objectives
This study aims to characterise sport-specific injury patterns across endurance & strength sports and determine whether acute spikes in ACWR is associated with greater injury incidence.
Study design & methods
A cross-sectional analysis of male & female semi-professional and professional athletes in endurance (n=30) and weight-category sports (n=30) over a 6 month period was undertaken after informed consent. Demographics, weekly and monthly training exposure, and self-reported injuries in the prior six months were recorded from team training logs. ACWR ratio was calculated for each athlete. The primary outcome was any self-reported injury (acute or overload) in the preceding six months (incidence proportion over the recall period). Analyses included descriptive injury profiles by sport and anatomical site, non-parametric comparison of ratio distributions between injured and non-injured athletes (Mann–Whitney U), and multivariable logistic regression modelling (injury yes/no) with the ratio as the primary predictor, adjusted for age, sex and chronic weekly training hours. Sensitivity analyses evaluated common ratio cut-points (reference 0.8–1.2; spikes ≥1.3 and ≥1.5). Statistical significance set at p<0.05.
Results
Median ACWR was 1.20 (IQR 1.00–1.36) in endurance athletes and 1.05 (IQR 0.92–1.18) in strength-based athletes. Athletes reporting injury in the prior six months had higher median ACWR (1.28, IQR 1.10–1.52) than non-injured athletes (1.05, IQR 0.92–1.20)(p<0.05). Using an ACWR spike threshold of ≥1.5, athletes exceeding this threshold had an adjusted odds ratio (OR) for injury of 2.2 (95% CI 1.3–3.7)( p=0.002) after controlling for age, sex and weekly training hours. Higher ACWR was independently associated with increased risk of injury (ACWR ≥1.5; adjusted OR 2.2, 95% CI 1.3–3.7) (p=0.002). These associations persisted across sensitivity analyses and showed larger effect sizes at higher thresholds.
Conclusions
Acute workload spikes were associated with greater injury probability in both endurance and strength sports. These epidemiological associations align with the broader workload–injury literature and indicate a measurable short-term risk signal following workload spikes. From a team-based injury prevention perspective, this study further ratifies the need for routine monitoring of short-term versus chronic workload and sport-specific vigilance for acute spikes. Implementation of sophisticated mobile/app based/remote workload monitoring & injury surveillance systems, coach and athlete education on progressive loading would be beneficial for injury prevention. Future prospective sport-stratified studies to refine thresholds and test load-management interventions would further refine these findings.
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