title: The acute:chonic workload ratio in relation to injury risk in professional soccer.
abstract: OBJECTIVE
  To examine the association between combined sRPE measures and injury risk in elite professional soccer.
  
  
  METHODS
  Observational cohort study.
  
  
  METHODS
  Forty-eight professional soccer players (mean±SD age of 25.3±3.1 yr) from two elite European teams were involved within a one season study. Players completed a test of intermittent-aerobic capacity (Yo-YoIR1) to assess player's injury risk in relation to intermittent aerobic capacity. Weekly workload measures and time loss injuries were recorded during the entire period. Rolling weekly sums and week-to-week changes in workload were measured, allowing for the calculation of the acute:chronic workload ratio, which was calculated by dividing the acute (1-weekly) and chronic (4-weekly) workloads. All derived workload measures were modelled against injury data using logistic regression. Odds ratios (OR) were reported against a reference group.
  
  
  RESULTS
  Players who exerted pre-season 1-weekly loads of ≥1500 to ≤2120AU were at significantly higher risk of injury compared to the reference group of ≤1500AU (OR=1.95, p=0.006). Players with increased intermittent-aerobic capacity were better able to tolerate increased 1-weekly absolute changes in training load than players with lower fitness levels (OR=4.52, p=0.011). Players who exerted in-season acute:chronic workload ratios of >1.00 to <1.25 (OR=0.68, p=0.006) were at significantly lower risk of injury compared to the reference group (≤0.85).
  
  
  CONCLUSIONS
  These findings demonstrate that an acute:chronic workload of between 1.00 and 1.25 is protective for professional soccer players. A higher intermittent-aerobic capacity appears to offer greater injury protection when players are exposed to rapid changes in workload in elite soccer players. Moderate workloads, coupled with moderate-low to moderate-high acute:chronic workload ratios, appear to be protective for professional soccer players.
authors.affiliation: Institute of Technology Tallaght, Ireland. Electronic address: shane.malone@mymail.ittdublin.ie.
authors.forename: Shane
authors.initials: S
authors.lastname: Malone
authors.affiliation: Servette Centre for Football Research (SCFR), Servette Football Club, Switzerland; Claude Bernard University Lyon, Centre de Recherche et d'Innovation sur le Sport (CRIS), France; BenficaLAB, S.L. Benfica, Portugal.
authors.forename: Adam
authors.initials: A
authors.lastname: Owen
authors.affiliation: Servette Centre for Football Research (SCFR), Servette Football Club, Switzerland.
authors.forename: Matt
authors.initials: M
authors.lastname: Newton
authors.affiliation: BenficaLAB, S.L. Benfica, Portugal.
authors.forename: Bruno
authors.initials: B
authors.lastname: Mendes
authors.affiliation: Institute of Technology Tallaght, Ireland.
authors.forename: Kieran D
authors.initials: KD
authors.lastname: Collins
authors.affiliation: Gabbett Performance Solutions, Australia.
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Gabbett
mesh_terms: D000328:Adult; D001265:Athletic Injuries / Q000209:etiology* / Q000517:prevention & control; D006801:Humans; D016015:Logistic Models; D016017:Odds Ratio; D005082:Physical Exertion; D011446:Prospective Studies; D065840:Protective Factors; D012307:Risk Factors; D012916:Soccer / Q000293:injuries* / Q000502:physiology; D013997:Time Factors; D016526:Workload
keywords: Injury prevention; Intermittent team sports; Odds risk; Training load; Yo-YoIR1