ECSS Paris 2023: OP-PN26
INTRODUCTION: For athletes, both intense exercise and adequate recovery are important to improve performance (Laursen, 2010; Bird, 2013). Inadequate quantities and quality of sleep following exercise can lead to impaired muscle functions and recovery of endurance performance (Fullagar et al., 2015). Previous studies have shown that high-intensity exercise at night reduces sleep quality (Oda and Shirakawa, 2014; Aloulou et al., 2019). However, these studies utilized land exercise (e.g., running, cycling), and the effects of swimming on sleep have not been elucidated. Therefore, the purpose of the present study was to clarify the effect of swimming exercise at night on subsequent sleep quality. We hypothesized that swimming exercise at night would disrupt sleep quality. METHODS: Ten male swimmers (mean±SD; age: 19.9±1.3 yrs, height: 174.6±4.8 cm, weight: 69.0±5.1 kg) performed two trials on different days with a randomized, counterbalanced order. Between 6:30 p.m. 8:30 p.m., participants performed either (i) a 2h swimming practice session including high-intensity exercise (SWIM) or (ii) maintaining the rest without exercise (CON). Subsequently, participants in both trials took a shower and ate prescribed dinner at the same time, and then slept from 11 p.m. to 7 a.m. Blood lactate concentrations were measured before and immediately after exercise (or rest). Moreover, core body temperature was measured continuously using a pill thermometer from 30 min before exercise (or rest) until the next morning. Sleep quality was assessed using electroencephalograms (EEG). RESULTS: Blood lactate concentrations markedly increased after exercise (pre: 1.9±0.6 mmol/l vs. after: 20.3±3.9 mmol/l, p<0.001 ). Mean core body temperature was significantly elevated during the swimming exercise compared to CON (SWIM: 37.8±0.4°C vs. CON: 37.1±0.2°C, p<0.001). However, no significant difference between conditions was found at bedtime (11 p.m.) and during sleep. Total REM sleep time was significantly decreased in SWIM compared with CON (SWIM: 82.4±27.1 min vs. CON: 107.6±39.5 min, p=0.039). However, other sleep variable (time of stage N1, 2, 3, total sleep time, sleep efficiency, sleep onset latency, REM sleep latency and wake after sleep onset) did not significantly differ between trials. CONCLUSION: Strenuous swimming practice at night (6:30 p.m.-8:30 p.m.) increased core body temperature but it did not change markedly sleep quality in male swimmers.
Read CV Hiroki FurukawaECSS Paris 2023: OP-PN26
INTRODUCTION: Up to 78% of athletes report poor quality sleep, with the average athlete obtaining less than seven hours per night (1). Acutely, insufficient sleep impairs technical and tactical performance, with the accumulation of sleep debt also seen to affect endurance (2, 3). As a result, poor-sleeping athletes are particularly vulnerable to performance decline. Prior research within poor-sleeping individuals suggests that the acute supplementation of a whey protein rich in the amino acid tryptophan (TRP), alpha-lactalbumin (ALAC), may be an effective strategy to improve sleep and physical performance (4, 5). Therefore, this study investigated whether sub-chronic supplementation of ALAC in the evening would improve the sleep and physical performance of a poor-sleeping athletic population. METHODS: Twenty-four athletically trained participants (females, n=7) with sleep difficulties (Athlete Sleep Screening Questionnaire: 8.6 ± 2.2, Pittsburgh Sleep Quality Index: 10.0 ± 3.0) completed this double-blinded, counterbalanced, randomised, cross-over trial. Participants were supplemented with 40 g of ALAC (1.9 g TRP) or an isocaloric placebo two hours prior to individualised bedtimes for seven consecutive nights within habitual settings. To minimise dietary influences on TRP levels, participants consumed standardised low-protein dinners (0.2 g/kg body weight) two hours prior to the supplement, with habitual diet replicated across trials. Sleep was assessed nightly using actigraphy, while subjective sleepiness, mood, and recovery questionnaires were completed every morning and evening. Following the seven-day supplementation period, physical performance testing was completed (i.e., 30-second countermovement jump test, Yo-Yo Intermittent Recovery Test Level 1, and reaction time) at Deakin University in a standardised sequence under controlled conditions. RESULTS: Compared to control, objective number of awakenings were increased (CON: 10.25 ± 5.28, ALAC: 11.01 ± 5.79; p=0.031), average jump height was reduced (CON: 28.58 ± 5.53 cm, ALAC: 27.68 ± 5.14 cm; p=0.037), subjective physical and mental performance capability were declined in the evening (p<0.001), and evening negative emotional states (p=0.001) were reduced during the ALAC condition. No other sleep, performance, or subjective outcomes were influenced following ALAC supplementation. CONCLUSION: Seven days of ALAC supplementation may not improve the sleep and physical performance of an athletically trained population with mild-moderate sleep difficulties. Future research should recruit populations with more severe sleep difficulties and measure sleep architecture over an extended period to fully ascertain the effects, and potential benefits, of ALAC supplementation for athletes. (1) Walsh et al. 2021; (2) Fullagar et al. 2015; (3) Roberts et al. 2019; (4) Miles et al. 2021; (5) Gratwicke et al. 2022
Read CV Jackson BarnardECSS Paris 2023: OP-PN26
INTRODUCTION: During military training, physical activity and psychological stress drive increased average cortisol levels and glucose mobilisation which, if sustained, may impair physical and mental health. An inverse relationship is commonly observed between cortisol and androgens which may impede physical and mental training outcomes. This study aimed to explore cortisol, androgen and glucose changes during the RANGER Assessment Cadre (RAC), a 10-day advanced selection course where candidates undergo intense exercise for selection into this elite regiment. METHODS: Observational study of glucocorticoid and androgen profiles, overnight glucose, stress and sleep during the RAC. Saliva was sampled at 0530, 0700, 1500, 1800 and 2200 on days 1 and 10, continuous interstitial glucose (Dexcom G7) and physical activity and sleep (GENEActiv) were measured throughout. Perceived stress scale (PSS) and Connor-Davidson Resilience-10 (CDRISC-10) were measured on days 1 and 10. Salivary cortisol, cortisone, testosterone (T), androstenedione (A4) and dihydroepiandrostenedione (DHEA) were measured via tandem mass spectrometry. Morning cortisol rise (0530 to 0700) and areas under the 5-point day curve (AUC) were calculated. Days 1 and 10 were compared using t-tests. RESULTS: 17 men completed the study, aged 22 ±8 years. From day 1 to 10, morning cortisol rise and area under the curve (AUC) cortisol decreased (d 1.81, d 0.67, both p<0.05), and morning cortisol:cortisone ratio decreased (d 0.99, p=0.03) but did not change at other times of day (p>0.3). We found no change in morning androgens (p>0.7) but a marked increase in evening T, A4 and especially DHEA (d 0.91, d 1.5, d 5.3, respectively, p<0.0001; 13.3- fold rise in DHEA, 18.6-fold rise in DHEA:cortisol ratio). Mean overnight glucose increased (4.3±1.0 mmol/L vs 5.2 ± 0.9 mmol/L, p<0.001). Participants slept 6.2±2.2 hours per night including 1.7±1.3 hours on night 5. PSS and CDRSIC-10 were 11 ±5 and 34 ±4 respectively on day 1 and did not change by day 10 (p>0.7). CONCLUSION: After an arduous 10-day cadre, morning cortisol and cortisol:cortisone decreased and evening cortisol was unchanged, yet overnight hyperglycaemia was demonstrated, suggesting metabolic dysregulation and increased average cortisol exposure. A dissociated cortisol-androgen response, with a pronounced rise in evening preandrogens, is a novel finding and may represent a buffering response to preserve the cognitive impact of sleep deprivation.
Read CV Aaron HuntECSS Paris 2023: OP-PN26