Strategic Daytime Napping Enhances Agility and Lowers Perceived Exertion But Does Not Improve Fatigue Resistance in Adolescent Soccer Players

Background Daytime napping is increasingly incorporated into athletic recovery routines to manage sleepiness and support alertness. However, the effects of different nap durations on high-intensity anaerobic performance tasks remain insufficiently characterized, particularly in team-sport settings. Nap duration and circadian timing may influence psychomotor readiness, perceived exertion, and fatigue-related responses, yet existing evidence is limited and inconsistent in adolescent athlete populations. This study is designed to examine the acute effects of two daytime nap durations within a controlled experimental framework. Methods This study will employ a randomized, crossover design involving sixteen competitive male adolescent soccer players classified as intermediate chronotypes. Each participant will complete three experimental conditions in a randomized order: no nap (N0), a 25-minute nap (N25), and a 45-minute nap (N45), with standardized washout periods between sessions. Nap compliance will be objectively monitored using wrist-worn actigraphy. Following each condition, participants will observe a standardized 60-minute post-nap wakefulness period prior to performance testing. Agility performance will be assessed using the Pro Agility Test, and anaerobic endurance will be evaluated using a repeated-sprint ability (RSA) protocol. Psychophysiological measures will include ratings of perceived exertion (RPE), the Hooper Index, visual analogue scales (VAS) for subjective alertness, and mood states assessed via the Profile of Mood States (POMS). These outcomes will be collected to compare responses across nap conditions. Objectives The primary objective of this study is to compare the acute effects of two daytime nap durations (25 minutes vs 45 minutes) on agility performance in adolescent soccer players without a habitual napping routine. Secondary objectives include examining nap-related differences in repeated-sprint performance indices, perceived exertion, subjective alertness, and mood states. Keywords daytime nap; athletic recovery; agility; repeated-sprint ability; perceived exertion; mood; chronotype