Repeated Exposure to Established High Risk Workload Scenarios Improves Non-Contact Injury Prediction in Elite Australian Footballers

Colby, M.J., Dawson, B., Peeling, P., Heasman, J., Rogalski, B., Drew, M.K., Stares, J.

Objectives: To assess the effect of multiple high risk scenario (HRS) exposures on non-contact
injury prediction in elite Australian footballers. Design: Retrospective cohort study. Methods:
Sessional workload data (session-rating of perceived exertion; GPS-derived distance, sprint
distance, maximum velocity) from one club (n= 60 players) over 3 seasons were collated;
several established HRS were also defined. Accumulated HRS sessional exposures were
calculated retrospectively (previous 1-8 weeks). Non-contact injury data was documented.
Univariate and multivariate Poisson regression models determined injury incidence rate ratios
(IRR) while accounting for moderating effects (pre-season workload volume, playing
experience). Model performance was evaluated using receiver operating characteristics (area
under curve: AUC). Results: Very low (0-8 sessions: IRR=5.76, 95% CI=1.69-19.66) and very
high (>15 sessions: IRR=4.70, 95% CI=1.49-14.87) exposures to >85% of an individual’s
maximal velocity over the previous 8 weeks were associated with greater injury risk compared
to moderate exposures (11-12 sessions), and displayed the best model performance
(AUC=0.64). A single session corresponding to a very low chronic load condition over the
previous week for all workload variables was associated with increased injury risk, with sprint
distance (IRR=3.25, 95% CI=1.95-5.40) providing the most accurate prediction model
(AUC=0.63). Conclusions: Minimal exposure to high velocity efforts (maximum speed
exposure, sprint volume) was associated with the greatest injury risk. Being under-loaded may
be a mediator for non-contact injury in elite Australian football. Pre-season workload and
playing experience were not moderators of this effect.