Variations in Elite Female Soccer Players' Sleep, and Associations With Perceived Fatigue and Soccer Games.

Frode Moen,Maria Hrozanova,Maja Olsen,Gunvor Halmøy

doi:10.3389/fspor.2021.694537

Abstract

The current study investigated the associations between female perceived fatigue of elite soccer players and their sleep, and the associations between the sleep of players and soccer games. The sample included 29 female elite soccer players from the Norwegian national soccer team with a mean age of ~26 years. Perceived fatigue and sleep were monitored over a period of 124 consecutive days. In this period, 12.8 ± 3.9 soccer games per player took place. Sleep was monitored with an unobtrusive impulse radio ultra-wideband Doppler radar (Somnofy). Perceived fatigue was based on a self-report mobile phone application that detected daily experienced fatigue. Multilevel analyses of day-to-day associations showed that, first, increased perceived fatigue was associated with increased time in bed (3.6 ± 1.8 min, p = 0.037) and deep sleep (1.2 ± 0.6 min, p = 0.007). Increased rapid eye movement (REM) sleep was associated with subsequently decreased perceived fatigue (−0.21 ± 0.08 arbitrary units [AU], p = 0.008), and increased respiration rate in non-REM sleep was associated with subsequently increased fatigue (0.27 ± 0.09 AU, p = 0.002). Second, game night was associated with reduced time in bed (−1.0 h ± 8.4 min, p = <0.001), total sleep time (−55.2 ± 6.6 min, p = <0.001), time in sleep stages (light: −27.0 ± 5.4 min, p = <0.001; deep: −3.6 ± 1.2 min, p = 0.001; REM: −21.0 ± 3.0 min, p = <0.001), longer sleep-onset latency (3.0 ± 1.2 min, p = 0.013), and increased respiration rate in non-REM sleep (0.32 ± 0.08 respirations per min, p = <0.001), compared to the night before the game. The present findings show that deep and REM sleep and respiration rate in non-REM sleep are the key indicators of perceived fatigue in female elite soccer players. Moreover, sleep is disrupted during game night, likely due to the high physical and mental loads experienced during soccer games. Sleep normalizes during the first and second night after soccer games, likely preventing further negative performance-related consequences.

Highlights

Playing soccer games and high-intensity training sessions at the elite level involves demanding physical efforts with high-intensity sprinting, sudden changes in running speed, accelerations, movement directions, hard tackles, and often maximal jumps (Nédélec et al, 2012)
Random intercept models investigating the associations between perceived fatigue (IV) and sleep variables (DVs) showed that with each point increase in perceived fatigue, time in bed (TIB) of athletes increased by 3.6 ± 1.8 min
The intraclass correlation (ICC) value showed that 7% of the total variance in TIB was due to differences between participants

Summary

Introduction

Playing soccer games and high-intensity training sessions at the elite level involves demanding physical efforts with high-intensity sprinting, sudden changes in running speed, accelerations, movement directions, hard tackles, and often maximal jumps (Nédélec et al, 2012). Both subjectively and objectively quantified physical efforts peak significantly during soccer games (Whitworth-Turner et al, 2018; Lathlean et al, 2019). Such physical efforts lead to muscle damage, which is associated with a marked inflammatory response and upregulated oxidative stress during recovery (Nédélec et al, 2013). Optimal functioning and recovery are thought to be associated with respiration rate (RP) (Davies and Maconochie, 2009; Nijman et al, 2012; Bennett et al, 2015)

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