Sleep-related metrics that predict training intensity: an exploratory study in women's college athletics

In recent years, the development of wearable monitoring technologies has expanded objective assessments of workload and fatigue, predominantly via heart rate (HR)-based markers (e.g., heart rate variability, resting heart rate). There are also perception-based markers of exertion commonly used in high-performance training settings, such as rating of perceived exertion (RPE) scales. Previous research has shown that these markers do not measure identical but rather complementary aspects of exertion, but limited data exist on the relationships between objective and subjective markers at the daily level; data which may be especially important for understanding how to best monitor for effort or overtraining. This study will characterize both HR- and perception-based markers of exertion at the daily level in women's college athletes. Additionally, given the powerful influence of sleep on both athletic performance and perceptions of physical exertion, we further explored how sleep behaviors at the within- and between-person level relate to daily assessments of subjective and objective exertion.

Thirteen women's college athletes continuously wore a WHOOP activity monitor for this two-week observational study. RPE was self-reported within 30 min of completing a training session or competition and prior to viewing WHOOP data.

A series of descriptive statistics and Pearson correlation were conducted to describe the relationship between RPE and activity strain on a daily level among the population studied. A series of linear mixed-effects models demonstrated worse sleep on average (i.e., more debt, poorer sleep performance) was associated with higher HR-based markers of exertion; however, within-person elevations in sleep consistency, but more sleep need on average was associated with higher HR-based measures of exertion and lower perceptions of exertion.

Findings support the need for additional research to better understand the drivers of daily markers of exertion to enhance the health and performance of athletes.