Comparison of Functional Performance of Amateur Triathletes According to Average Sleep Duration and Sleep Behavior
sleep, athletic performance, postural balance, physical endurance
Background: Sleep plays a fundamental role in recovery and athletic performance, especially in high-demand sports such as triathlon. In addition to sleep duration, sleep behavior, including habits, regularity, and hygiene, may also impact physical performance. However, there is a lack of studies using objective measures of functional performance in triathletes. Objectives: To compare functional performance — through peripheral muscle endurance and dynamic balance tests — among triathletes with different sleep behavior profiles, as well as between groups with average monthly sleep durations above and below 6h30 per night. Methods: This was a cross-sectional study involving 52 amateur triathletes, classified into three groups based on sleep behavior (good, moderate, and poor) using the Athlete Sleep Behavior Questionnaire (ASBQ), and into two groups based on average monthly sleep duration (≥6h30 and <6h30 per night). Clinical tests for shoulder, hip, and plantar flexor endurance were applied, along with the Y-Balance Test (YBT) to assess dynamic balance. Statistical analyses included ANOVA, Student’s t-test, MANOVA, and Spearman correlation (p ≤ 0.05). Results: Triathletes with an average sleep duration ≥6h30min per night showed better performance in the YBT compared to the group with an average sleep duration <6h30 min. The greatest reaches for the dominant side were: anterior (MD = 3.76 cm; 95% CI: 0.34 to 7.17) and posteromedial (MD = 6.43 cm; 95% CI: 0.80 to 12.06), as well as the composite score (MD = 6.42 cm; 95% CI: 0.39 to 12.44). For the non-dominant limb (NDOM), the posterolateral reach was greater (MD = 6.38 cm; 95% CI: 1.10 to 11.67). Regarding sleep behavior, a significant difference was found only in the endurance of the non-dominant shoulder external rotators (p = 0.038), with lower values in the group with poorer sleep behavior. A negative correlation was also observed between the ASBQ score and NDOM shoulder endurance (ρ = –0.318; p < 0.05). No other variables showed significant differences between groups. Conclusion: Greater average sleep duration is associated with better performance in dynamic balance tasks, while poorer sleep behavior is linked to reduced localized muscle endurance. Incorporating sleep monitoring into sports training may support injury prevention and performance optimization in triathletes. Further longitudinal studies using objective sleep assessments are recommended