Differences In Absolute And Relative On-ice Workload Metrics Among National Junior Ice-hockey Teams

Abstract

PURPOSE: Use player worn sensors (PWS) to measure and compare absolute and relative training load metrics for U17 and U18 Junior National ice hockey teams during practices and games. METHODS: 90 total members of two teams (U17, n= 45 and U18, n= 45) of the National Team Development Program (16.6+2.1y, 17.5+2.7y) consented to procedures approved by the EMU-HSRC. Zephyr BH-3 (Zephyr, MD) PWS measured triaxial accelerations (g’s) for all on ice practices (P) and games (G). Dynamic Accelerations (DYNAs) were generated from exponentially weighted accelerations and Dynamic Functional Threshold (DFT) from peak 30 min DYNAs within a 2 week moving window. Intensity Factor (IF) and Individual Hustle Score (IHS) were derived from session and 30 min DYNAs relative to DFT, respectively. Dynamic Training Load (DTL) for a single session was derived from the IF and the session duration. DTL was used as the input for a model to calculate Chronic Training Load (CTL), Acute Training Load (ATL) over a given amount of time. MANOVA was used to compare metrics by session type, (G) vs (P), and between teams for main effects (α=.05). RESULTS: : For G, duration was not different between teams. However, 30 minute and session DYNAs, as well as DTL and IHS, were lower for U18 (0.360+0.056, 0.293+0.052, 176.2+55.2, 0.904+0.131) than U17 (0.372+0.044, 0.307+0.038, 187.3+44.3, 0.928+0.092; p<0.05). In P, duration was higher in U18 (1.93+0.53) than U17 (1.74+0.50; p<0.05). 30 minute and session DYNAs were not different between teams, but IHS and IF were lower for U18 (0.894+0.112, 0.768+0.098) than U17(0.897+0.101, 0.790+0.096; p<0.05). Despite lower IHS and IF, DTL was higher for U18 (114.4+35.9) than U17(109.8+38.6; p<0.05). Overall, for P and G, duration was longer for U18 than for U17 (2.35+0.79, 2.21+0.83; p<.05). IF and IHS were lower for U18 (0.757+0.111, 0.895+0.119) than U17 (0.783+0.094, 0.907+0.100; p<0.05). CTL and ATL were higher for U18 (69.9+14.8, 85.1+24.4) than U17 (63.5+17.3, 77.2+25.3). CONCLUSIONS: Relative intensity measures, such as IHS and IF, were more sensitive in determining load than absolute, unnormalized measures such as DYNAs. Duration of training sessions were longer for U18, leading to higher CTL even with lower intensity. This may be of importance as higher CTL has been associated with higher fitness and resilience to injury.