Author(s): SUZUKI, M., TOMOTAKA, N., HIROKI, F., RIN, M., KAZUSHIGE, G., Institution: RITSUMEIKAN UNIVERSITY, Country: JAPAN, Abstract-ID: 1896

INTRODUCTION:
Sleep is a key component for psychological and physiological recovery during intensified training period in athletes. However, athletes tend to experience reduced sleep quality and quantity due to multiple factors such as excessive training and nighttime practice sessions (Chunha et al.,2023). Insufficient sleep delays glycogen resynthesis and neuromuscular recovery (Coel et al.,2023). Currently, previous studies with focusing on “exercise and sleep” mainly utilized endurance exercise, but we are aware that the impact of intensified resistance training on sleep quality has not fully elucidated. Therefore, the present study aimed to clarify the effects of 2 weeks of intensified resistance training on sleep quality and nocturnal physiological variables.
METHODS:
Ten men and women (age 21.8 ± 1.4 years) underwent 2 weeks (week1, week2) of resistance training (4 days/wk). Each session program consisted of 6 exercises consisting of 5sets × 8 reps (for bodyweight bearing exercise: 3 sets × 20 reps), with 2 min rest between sets and exercises. During the third week (week 3), participants did not join any training session. During 3 weeks of intervention period, sleep quality was evaluated at participant’s home using portable EEG devices. Also, heart rate variability (HRV) and skin temperature during sleep were record. Additionally, exercise load (weight lifted × repetitions), salivary hormones (testosterone and cortisol concentrations), subjective muscle soreness (evaluated by visual analogue scale), and physical activity levels were assessed.
RESULTS:
In sleep EEG, wake time after sleep onset (WASO) and time of stage N1 were significantly higher in week 1 (WASO: 11 ± 10 min, N1: 8.5 ± 3.5 min) compared to week 3 (WASO: 3 ± 2 min, N1: 4.5 ± 1.6 min, P < 0.01). No significant changes over time were observed for total sleep time. Sleep efficiency, sleep latency, REM latency, or the proportion of N2 and N3 did not change significantly over 3 weeks (P > 0.05). Heart rate during sleep was significantly higher in week 2 (55 ± 5 bpm) than in week3 (52 ± 4 bpm, P < 0.05). However, LF/HF (HRV variable) and skin temperature during sleep did not differ significantly over 3 weeks (P > 0.05).
CONCLUSION:
A key finding of the present study was that intensified resistance training (4 days/wk) increased WASO and time of N1 during the first training week (week 1). Previous study reported that 6 consecutive days of intensified interval training decreased sleep quality (Wiewelhove et al.,2016). Since score of muscle soreness was significantly elevated during week 1, resistance exercise-induced muscle soreness may affect the impaired sleep quality. During the week3, decreased sleep quality was not observed, which would be associated with cessation of the training.
Two weeks of intensified resistance training partially decreased sleep quality.