The Severity of Impacts During Low-Speed Water Skier Falls

Background: Little kinematic or kinetic information is available to understand risks associated with water skier falls. The present study assessed accelerations during low-speed falls and then contrasted these data against information obtained from automotive crash tests to better delineate risk of injury. The goal was to establish baseline impact information for low-speed falls during water skiing. Methods: Twenty-seven experienced skiers were asked to deliberately make replicate forward falls at 20 miles per hour. A three-axis, electronic, waterproof accelerometer monitored either the torso or head during these maneuvers and recorded the magnitude of impacts in multiples of the force of gravity (e.g., ‘g’s’). Both anatomical sites were assessed for each participant. Data were averaged for the replicate runs. Using these averages, grand means were calculated for accelerations encountered along each of the three orthogonal axes measured. As well, 95% confidence intervals of these grand means were calculated. Peak accelerations were identified for each of the three orthogonal axes measured and plotted against time to estimate durations of acceleration events (impulse). Results: Grand means for torso accelerations ranged from 2.7 g’s (95% CI: 1.6-3.9) to 3.6 g’s (95%CI: 2.5-4.6). Grand means for head accelerations ranged from 2.5g (95%CI: 1.6-3.4) to 2.6g (95%CI: 1.4-3.8). Peak accelerations did not exceed 44 g’s for any participant. The average duration of these accelerations was approximately 110 milliseconds. Conclusions: The average magnitude of accelerations during low-speed water skier falls approximates 2-4g’s for either the head or torso. Based on a recent report of a 50-g threshold for brain injury, these impacts pose little risk of serious