Intra-individual variability of sleep and nocturnal cardiac autonomic activity in elite female soccer players during an international tournament

Abstract

PurposeTo describe individual sleeping patterns and nocturnal cardiac autonomic activity of National team female soccer players during an international tournament.Materials and methodsTwenty elite female soccer players (aged 25.2±3.1 years) wore wrist actigraph units and heart rate (HR) monitors during night-sleep throughout 9 consecutive days (6 day-time training sessions [DT], 2 day-time matches [DM], and 1 evening-time match [EM]) of an international tournament. Training and match loads were monitored using the session-rating of perceived exertion (s-RPE) and wearable 18-Hz GPS (total distance covered [TD], training and match exposure time, and high-speed running [HSR]) to characterize training and match loads.ResultsIndividually, s-RPE, TD, exposure time, and HSR during training sessions ranged from 20 to 680 arbitrary units (AU), 892 to 5176 m, 20 to 76 min, and 80 to 1140 m, respectively. During matches, s-RPE, TD, exposure time, and HSR ranged from 149 to 876 AU, 2236 to 11210 m, 20 to 98 min, and 629 to 3213 m, respectively. Individually, players slept less than recommended (<7 hours) on several days of the tournament, especially after EM (n = 8; TST ranging between 6:00–6:54 h). Total sleep time coefficient of variation (CV) ranged between 3.1 and 18.7%. However, all players presented good sleep quality (i.e., sleep efficiency ≥75%; individual range between: 75–98%) on each day of the tournament. Most of the players presented small fluctuations in nocturnal cardiac autonomic activity (individual nocturnal heart rate variability [HRV] ranged from 3.91–5.37 ms and HRV CV ranged from 2.8–9.0%), while two players presented higher HRV CV (11.5 and 11.7%; respectively).ConclusionOverall, this study highlights the substantial individual variability in sleep and HRV measures, suggesting the adoption of an individual approach to monitor sleep, training and match loads and recovery, to better understand how players cope with highly demanding competitions.

Sleep Indices and Cardiac Autonomic Activity Responses during an International Tournament in a Youth National Soccer Team

“…In the current study, no significant changes in HRV indices across the 5-day tournament and an unclear within-subject correlation with s-RPE were observed. Our finding is in line with the results described in elite female national soccer players [ 20 ]. Other studies also reported that the fitter young soccer players with greater exercise tolerance had lower daily allostatic perturbation, leading to smaller daily changes in lnRMSSD, and in turn, lower CV values, as well as reduced perceived fatigue [ 45 ].…”

“…Accelerometer data were extracted using the Sadeh’s (S) algorithm—originally validated on a healthy sample of adolescents and young adults (age range 10–25 years) [ 28 ]. Sleep outcomes included sleep duration (amount of sleep hours) and sleep efficiency (percentage of time in bed that was spent asleep) [ 20 , 28 ] were analyzed according to the National Sleep Foundation guidelines [ 2 ]. A sleep duration <8 h was considered an indicator of inappropriate sleep quantity, and a sleep efficiency ≤74% was considered an inappropriate sleep quality.…”

“…However, studies describing the variation on nocturnal HRV after exercise (i.e., training and/or competition) sessions, especially in young athletes, are lacking. Additionally, studies exploring the associations between training and matches loads with nocturnal HRV are scarce, and none have studied young soccer players [ 20 ].…”

“…Finally, most previous studies have focused on group data to analyze sleep and HRV changes in soccer players [ 21 , 22 , 23 , 24 , 25 ], which has limited capacity to detect individual responses. Although individual analysis methods have recently been used to track individual changes [ 20 , 26 , 27 ], these methods have not been used to analyze data on sleep and nocturnal HRV variability in youth soccer players.…”

COVID-19-Related Restrictions and Quarantine COVID-19: Effects on Cardiovascular and Yo-Yo Test Performance in Professional Soccer Players

“…Cardiovascular fitness is one of the most important aspects of physical fitness in soccer (Castagna et al, 2017;Slimani and Nikolaidis, 2019). During professional competitions, athletes dispute between two and five games per month, with each game lasting for ∼90 min, a time span, that, in case of a tie, can be extended (Castagna et al, 2010;Costa et al, 2019). Moreover, athletes have training sessions twice a day during the competitive season and take part in national and international championships (Slimani et al, 2018b).…”