Accelerometer-based Measurement of Physiological and Physical Intensity in Male Ice Hockey Players

PURPOSE: Wearable technologies are increasingly used to monitor athletes across a range of sports. Ice hockey is uniquely suited to the use of accelerometers due to the physical nature of the sport and the rapid directional changes required to perform in a confined space. The purpose of this study was to develop accelerometer-based metrics representing high physiological and physical intensity in male ice hockey players. METHODS: Skaters on a junior hockey team playing in the United States Hockey League wore triaxial accelerometers during 36 regular season games and 10 playoff games. Accelerations in 3 planes of motion were recorded at 100 Hz with the resultant calculated for each time interval and reported as gravitational force equivalent (G-force). For each game the time spent above 1.1G, 1.2G, etc. was calculated for 0.1G increments up to time above 6.0G. These times were expressed as a percentage of the player’s time on ice (TOI) for each game. The G-force threshold above which no player had a time that exceeded 50% of their TOI was defined as activity representing high physiological intensity. High physical intensity was defined as the G-force threshold at which no player had a time that exceeded 1% of their TOI. Mixed model analysis of variance was used to compare physiological and physical intensity between forwards and defensemen and between regular season and playoff games. RESULTS: Time above 1.4G averaged 31 ± 6% of TOI with a range of 15-48% (high physiological intensity). Time above 4.0G averaged 0.23 ± 0.12% of TOI with a range of 0-1% (high physical intensity). Forwards spent a greater proportion of their TOI at a high physiological intensity than defensemen (33 ± 6% vs. 27 ± 4%, P < 0.001). Forwards also spent a greater proportion of their TOI at a high physical intensity versus defensemen (0.27 ± 0.12% vs. 0.16 ± 0.06%, P < 0.001). The proportion of TOI spent at high physiological intensity was slightly decreased (4%) in the playoffs (30 ± 6% vs. 31 ± 6%, P = 0.008). However, the proportion of TOI spent at a high physical intensity was increased (15%) in the playoffs (0.26 ± 0.12% vs. 0.23 ± 0.11%, P < 0.001). CONCLUSIONS: Physiological and physical intensity in ice hockey can be quantified using an inexpensive triaxial accelerometer. Forwards had 24% higher physiological intensity and 68% higher physical intensity than defensemen.