Analysis of Sleep, Nocturnal Physiology, and Physical Demands of NCAA Women's Ice Hockey Across a Championship Season

Abstract

The aims of this study were threefold 1) determine the relationship of daily physical demands on that night’s sleep and physiological recovery via nocturnal heart rate (HR) and heart rate variability (HRV); 2) evaluate changes in weekly sleep patterns and nocturnal HR and HRV over the course of a competitive season in NCAA women’s ice hockey; 3) determine overall differences between days and nights before training and competition. Twenty-five NCAA Division I women’s ice hockey athletes wore a wearable sensor (Ōura Ring) every night throughout the season to monitor sleep quantity/quality (e.g., time in bed, time asleep, sleep efficiency) and nocturnal physiology (e.g., HR, HRV). During training and competitions (31 regular-season plus 7 post-season games), athletes wore a performance monitoring system (Polar Team Pro) to assess workload demands (e.g., HR and training impulse, TRIMP). Longitudinal hierarchical linear regression models and correlations were used to assess the relationship between daily physical demands and nocturnal physiology and sleep metrics, as well as weekly trends over time. Analyses of variance and T-tests were used to evaluate the differences across season blocks and positional groups, as well as between competition and training (p ≤ 0.05). As daytime TRIMP, Time > 80% of HRmax, and average HR increased, nocturnal HRV decreased and nocturnal HR increased. As daily workload metrics increased, Sleep Duration, Sleep Score, and Readiness Score decreased that night. Across the season, athletes experienced autonomic imbalance (lower HRV), but exhibited longer sleep durations. Training Distance, Duration, Time Above 80% Max HR, Average HR, and TRIMP revealed negative slopes across weeks in the competitive season, while competitions noted positive slopes (increases) for Total Distance, Duration, and TRIMP. There were also differences across positions and season blocks when evaluating these data at the mesocycle level. Lastly, no differences existed in nocturnal physiology before game days whereas sleep durations were significantly longer on nights before competitions compared to training nights. Competitions, on average, resulted in greater physiological demands. Autonomic Nervous System (ANS) states of the athletes decreased as the season progressed, likely due to accumulated demands of competitions that increased over time into post-season tournaments. We speculate that the increased focus on sleep hygiene, as evidenced by the increase in sleep over the season, may have served as a recovery aid to limit the magnitude of ANS disruption and increased preparedness prior to competitions as the season progressed.

Emaly Vatne

Assistant Sport Scientist at The Ohio State University Department of Athletics and Human Performance Collaborative

My research interests include applied sport science, effects of recovery interventions, and data analysis, visualization, and engineering.