Nap Opportunity During the Daytime Affects Performance and Perceived Exertion in 5-m Shuttle Run Test.

Omar Boukhris,David W Hill,Hamdi Chtourou,Florian A Engel,Raouf Abdessalem,Khaled Trabelsi,Achraf Ammar,Billy Sperlich,Hsen Hsouna

doi:10.3389/fphys.2019.00779

Abstract

PurposeTo compare the effect of different durations of nap opportunity during the daytime on repeated high-intensity short-duration performance and rating of perceived exertion (RPE).MethodsSeventeen physically active men (age: 21.3 ± 3.4 years, height: 176.7 ± 5.9 cm, body mass: 71.8 ± 10.2 kg) performed a 5 m shuttle run test [to determine best distance (BD), total distance (TD), and fatigue index (FI)] under four conditions: a 25 min nap opportunity (N25), a 35 min nap opportunity (N35), a 45 min nap opportunity (N45), and control condition (no-nap) (N0). The sleep quality of each nap opportunity was evaluated using a scale ranging from 0 “no sleep” to 10 “uninterrupted, deep sleep throughout.” The four conditions were performed in a random order. RPE was recorded after each repetition of the 5 m shuttle run test and the mean score was calculated.ResultsBD increased after N25 (+6%) and N45 (+9%) compared to N0 (p < 0.05) and was significantly higher after N45 compared to N35 (p < 0.05). Compared to N0, the three nap opportunity durations enhanced TD (p < 0.05) with greater enhancement after N45 compared to N25 (+8% vs. +3%) and N35 (+8% vs. +3%). For FI, no-significant differences were observed between the three nap opportunity durations and N0. The mean RPE score was significantly higher after N25 (+20%) and N0 (+19%) compared to N45 (p < 0.05). All participants were able to fall asleep during each nap condition with a sleep quality score of 6.9 ± 1.0, 7.0 ± 0.7, and 7.1 ± 0.8 for N25, N35, and N45.ConclusionA nap opportunity during the daytime was beneficial for physical performance and perceived exertion with the N45 being the most effective for improving performance and reducing fatigue during the 5 m shuttle run test. The implication of the present study is that athletes might benefit from a nap opportunity of 25, 35 or 45 min before practice or before a competition.

Highlights

Wakefulness and sleep are modulated by the internal biological clock located in the brain at the hypothalamus, and precisely, in the suprachiasmatic nuclei (Van Dongen and Dinges, 2000)
Total Distance (TD) A Friedman test conducted on Total distance (TD) data revealed a significant effect of Condition
The present study reported that the rating of perceived exertion (RPE) mean scores during the 5-m shuttle run test were significantly lower after N45 in comparison to N0 which could explain the increases in performance during this short-duration high-intensity exercise

Summary

Introduction

Wakefulness and sleep are modulated by the internal biological clock located in the brain at the hypothalamus, and precisely, in the suprachiasmatic nuclei (Van Dongen and Dinges, 2000). The impact of the biological clock goes beyond governing sleep and wake processes (Van Dongen and Dinges, 2000). It regulates the sleep/wake system and many other functions, such as blood pressure, hormone levels, body temperature, physical performance, alertness, mood and intellectual abilities that fluctuate during the day (Davenne, 2009). The post-lunch dip is a period of sleepiness that occurs between 13h00 and 16h00 due in part to a slight reduction in core body temperature, which promotes a tendency to sleep (Van Dongen and Dinges, 2000) and causes a temporary decrease in vigilance (Monk, 2005). The post lunch-dip is not completely explained by meal ingestion, but, rather reflects the 12 h harmony (i.e., 12 h sinusoids; e.g., the size of the 12 h component rhythm amplitude of core temperature) of the circadian clock (Monk, 2005)

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