The effect of impact location, velocity, and frequency on head injury criterion during ice hockey helmet drop tests

Background This study investigated whether differences in ice hockey helmet protection performance at varying impact velocities influence head injury risk. Methods Linear acceleration data were recorded during drop tests on 24 ice hockey helmets by using a uniaxial accelerometer in a collision test machine under low- and ambient-temperature environments for sequential low-, medium-, and high-velocity impacts. Head injury criterion (HIC), seasonal injury risk (SIR) under different impact velocities, and total seasonal injury risk (TSIR) were calculated for each helmet location. Results In both temperature environments, the back, front, and side locations produced higher TSIR than the top. Under low-velocity impacts, the side location produced higher SIR and HIC than the back and front. Under medium- and high-velocity impacts, the side location produced lower SIR than the back and front, or showed no difference compared to the back. Except for comparisons between the side and back/front under low-velocity impacts, SIR and HIC differences across locations were inconsistent or nonsignificant. Conclusion These findings suggest that under low-velocity impacts, the higher HIC at the side location may be a key factor influencing head injury risk. To enhance helmet protective performance, optimizing energy absorption at the side location during low-velocity impacts is recommended.