Effect of high-speed running on hamstring strain injury risk

Background Hamstring strain injuries (HSIs) are common within the Australian Football League (AFL) with most occurring during high-speed running (HSR). Therefore, this study investigated possible relationships between mean session running distances, session ratings of perceived exertion (s-RPE) and HSIs within AFL footballers. Methods Global positioning system (GPS)-derived running distances and s-RPE for all matches and training sessions over two AFL seasons were obtained from one AFL team. All HSIs were documented and each player's running distances and s-RPE were standardised to their 2-yearly session average, then compared between injured and uninjured players in the 4 weeks (weeks -1, -2, -3 and -4) preceding each injury. Results Higher than 'typical' (ie, z = 0) HSR session means were associated with a greater likelihood of HSI (week -1: OR = 6.44, 95% CI = 2.99 to 14.41, p < 0.001; summed weeks -1 and -2: OR = 3.06, 95% CI = 2.03 to 4.75, p < 0.001; summed weeks -1, -2 and -3: OR = 2.22, 95% CI = 1.66 to 3.04, p < 0.001; and summed weeks -1, -2, -3 and -4: OR = 1.96, 95% CI = 1.54 to 2.51, p < 0.001). However, trivial differences were observed between injured and uninjured groups for standardised s-RPE, total distance travelled and distances covered whilst accelerating and decelerating. Increasing AFL experience was associated with a decreased HSI risk (OR = 0.77, 95% CI 0.57 to 0.97, p = 0.02). Furthermore, HSR data modelling indicated that reducing mean distances in week -1 may decrease the probability of HSI. Conclusions Exposing players to large and rapid increases in HSR distances above their 2-yearly session average increased the odds of HSI. However, reducing HSR in week -1 may offset HSI risk.