Relationship of measures of sleep quantity and quality with performance variables in ncaa division I female soccer players

BACKGROUND: The growth in popularity of women's soccer has led to an increased interest in the physical, physiological, and technical demands for these athletes. To meet these demands, optimal preparation and recovery are necessary. One growing area of interest in athletic performance is the role that sleep may have in preparation and recovery. However, details about sport-specific benefits of sleep are limited, particularly in female collegiate athletes. Athletes in the collegiate setting may suffer from lack of sleep due to the stresses of academics and athletics. Moreover, measurement of sleep in elite college soccer players using actigraphy does not exist in the literature. PURPOSE: To evaluate the relationship between sleep quantity and quality and soccer-specific performance variables in an elite group of female soccer players. METHODS: Eight NCAA college-aged competitive Division I women's soccer players (18--23 yrs) participated in the study. Global Positioning Systems (GPS), heart rate monitoring and video analysis technologies were used during matches along with 24-hour actigraphy through the season. Actigraphy was also used to measure sleep quantity and quality. Data were collected for all 26 matches but only four competitive matches were included in the analysis as they met the following requirements: an evening match beginning at 1900 EST, time zones were not traveled across, goal differential was no more than two points (indicating a high level of competition) and for players' data to be included they must have played at least 45 minutes of the 90-minute match. The night prior to the match was included for the data analyses of sleep quantity and quality. A multivariate analysis of variance (MANOVA) was utilized to determine whether the vectors of the means in groups of variables were significant. Paired t-tests were used to analyze if differences in variables of performance existed after the "best" and "worst" nights of sleep for quantity and quality. Significance was set at p<0.05. RESULTS: Mean sleep quantity and quality for the "best" (575.0 +/- 38.4 minutes, 91.9 +/- 2.6% of time in bed spent sleeping) and "worst" (416 +/- 57.6 minutes, 76.2 +/- 12.1% of time in bed spent sleeping) nights were significantly different. The MANOVAs were not significantly different for the physiological and physical variables for quantity and quality of sleep. No differences in performance variables were observed after "best" and "worst" quantity sleep matches. However, differences existed between "best" and "worst" quality of sleep. Percent time spent exercising above 85% of the maximal heart rate (HRmax) was significantly lower after the "best" night of sleep (30.2 +/- 13.5 vs. 47.9 +/- 24.3%). Heart rate exertion was higher after the "best" night of sleep (518.5 +/- 193.1 vs. 387.6 +/- 148.9 AU) meaning the athletes were exercising at higher heart rates throughout the match without spending as much time in the anaerobic zone (>85%HRmax). High metabolic load distance (distance running at speeds greater than 19 km/hr and distance accelerating or decelerating quickly (>2 m/s 2) was lower after the "best" quality night (11.8 +/- 3.6 vs. 16.3 +/- 6.0 yds/min) and the number of decelerations was higher after the "best" quality night (69.7 +/- 28.1 vs. 50.6 +/- 25.9) indicating less stress on the body. CONCLUSION: Quality of sleep is important for reducing the time spent exercising in the anaerobic zone (>85% HRmax). However the time spent exercising at high heart rates below the ventilatory threshold may be increased after a night of better sleep quality, indicating an increased aerobic capacity during a competitive women's soccer match.