490 FO59 – Hamstring strain injury risk factors in Australian football change over the course of the season

Background Hamstring strain injuries (HSIs) occur frequently in Australian Football. Objective To determine which factors were most predictive of HSIs during different stages of competition. Design Prospective cohort Setting Professional Australian Football Participants Male professional Australian Footballers (n=311) Assessment of Risk Factors Eccentric knee flexor strength and BFlh architecture were assessed at the start and end of pre-season and in the middle of the competitive season. Details of any prospective HSIs were collated by medical staff. Main outcome measurement Area under the curve (AUC) for injury risk prediction models. Results There were 70 HSIs reported (16, 33 and 21 in preseason, early in-season, and late in-season, respectively). Risk factors were different for pre-season, early in-season and late in-season HSIs. A combination of prior HSI, age, height and muscle thickness were most associated with pre-season injuries (median AUC, 0.83). Pennation angle and fascicle length had the strongest association with early in-season injuries (median AUC, 0.86). None of the input variables were associated with late in-season injuries (median AUC, 0.46). Identification of early in-season HSIs and late in-season HSIs was not improved by the magnitude of change of data across pre-season (median AUC, 0.67). Conclusion Risk factors associated with prospective HSIs were different across the season in professional Australian Football, with non-modifiable factors (prior HSI, age, and height) mostly associated with pre-season injuries. Early in-season HSIs were associated with modifiable factors, notably BFlh architectural measures. The prediction of in-season HSIs was not improved by assessing the magnitude of change in data across pre-season.