Seasonal Variations in Training Load, Sleep Parameters, and Hormonal Markers in Collegiate Male Rowers During the Off-Season

Background: Adequate sleep is essential for recovery and performance in athletes. Internal and external training loads closely relate to sleep, but few studies have examined their distinct off-season effects. This study investigated the relationships among training load, hormonal markers, and sleep parameters in collegiate male rowers. Methods: Eleven rowers were monitored over 4 months (October 2022–January 2023). Internal load was assessed via session ratings of perceived exertion, external load by accelerometry-based indicators, sleep variables by actigraphy and the Pittsburgh Sleep Quality Index, and hormonal status via salivary cortisol and testosterone. Repeated-measures analysis of variance and correlation and regression analyses were applied. Results: Training load showed significant temporal variation (p < 0.01), with October having the highest intensity. Increased loads were associated with poorer sleep outcomes, including reduced total sleep time (p < 0.05), higher latency (p < 0.05), and decreased efficiency (p < 0.05). External load was linked to fragmentation indices (wake after sleep onset, awakenings; p < 0.05), whereas internal load correlated with improved efficiency in certain months (p < 0.05). Hormonal fluctuations, particularly cortisol and testosterone, also correlated with sleep parameters (p < 0.05). Conclusions: Internal and external loads exerted distinct influences on sleep, supporting the hypothesis that both must be monitored. Sleep duration and efficiency emerged as modifiable targets for optimizing recovery and performance in athletes.