title: Training loads and injury risk in Australian football-differing acute: chronic workload ratios influence match injury risk.
abstract: OBJECTIVE
  (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.
authors: La Trobe Sport and Exercise Medicine Research Centre, College of Science, Health and Engineering, La Trobe University, Melbourne, Victoria, Australia.
authors: David L
authors: DL
authors: Carey
authors: La Trobe Sport and Exercise Medicine Research Centre, College of Science, Health and Engineering, La Trobe University, Melbourne, Victoria, Australia.|Essendon Football Club, Melbourne, Victoria, Australia.|School of Allied Health Sciences, Griffith University, Gold Coast, Queensland, Australia.
authors: Peter
authors: P
authors: Blanch
authors: SAS Analytics Innovation Lab, La Trobe Business School, La Trobe University, Melbourne, Victoria, Australia.
authors: Kok-Leong
authors: KL
authors: Ong
authors: La Trobe Sport and Exercise Medicine Research Centre, College of Science, Health and Engineering, La Trobe University, Melbourne, Victoria, Australia.
authors: Kay M
authors: KM
authors: Crossley
authors: La Trobe Sport and Exercise Medicine Research Centre, College of Science, Health and Engineering, La Trobe University, Melbourne, Victoria, Australia.|Essendon Football Club, Melbourne, Victoria, Australia.
authors: Justin
authors: J
authors: Crow
authors: La Trobe Sport and Exercise Medicine Research Centre, College of Science, Health and Engineering, La Trobe University, Melbourne, Victoria, Australia.
authors: Meg E
authors: ME
authors: Morris
mesh_terms: D000328:Adult; D056352:Athletes; D001265:Athletic Injuries / Q000453:epidemiology*; D001315:Australia; D005538:Football / Q000293:injuries*; D006801:Humans; D012307:Risk Factors; D012420:Running; D016526:Workload; D055815:Young Adult
keywords: Australian football; Injury prevention; Training load