Identifying High-Risk Loading Conditions for In-Season Injury in Elite Australian Football Players

Stares, J., Dawson, B., Peeling, P., Heasman, J., Rogalski, B., Drew, M., Colby, M., Dupont, G., Lester, L.

Objectives:
To examine different timeframes for calculating acute to chronic workload ratio (ACWR) and whether this variable is associated with intrinsic injury risk in elite Australian football players.

Design:
Prospective cohort study.

Methods:
Internal (session rating of perceived exertion: sRPE) and external (GPS distance and sprint distance) workload and injury data were collected from 70 players from one AFL club over 4 seasons. Various acute (1-2 weeks) and chronic (3-8 weeks) timeframes were used to calculate ACWRs: these and chronic load categories were then analyzed to determine the injury risk in the subsequent month. Poisson regression with robust errors within a generalized estimating equation were utilized to determine incidence rate ratios (IRR).

Results:
Altering acute and/or chronic timeframes did not improve the ability to detect high injury risk conditions above the commonly used 1:4 week ACWR. Twenty-seven ACWR/chronic load combinations were found to be “high-risk conditions” (IRR>1, p<0.05) for injury within 7 days. Most (93%) of these conditions occurred when chronic load was low or very low and ACWR was either low (<0.6) or high (>1.5). Once a high injury risk condition was entered, the elevated risk persisted for up to 28 days.

Conclusions:
Injury risk was greatest when chronic load was low and ACWR was either low or high. This heightened risk remained for up to 4 weeks. There was no improvement in the ability to identify high injury risk situations by altering acute or chronic time periods from 1:4 weeks.

View this research