Impact of Hydration Status on Sleep and Recovery After Heavy Resistance Exercise.

Sekiguchi, Y, Jiwan, NC, Appell, CR, Moya, RM, Ky, AT, Keefe, MS, Dunn, RA, and Luk, H-Y. Impact of hydration status on sleep and recovery after heavy resistance exercise. J Strength Cond Res XX(X): 000-000, 2025-The purpose of this study was to examine the effects of hydration status on sleep and recovery measurements before and after heavy resistance exercise (RE). Eight resistance-trained men (age, 21 ± 2 years; body mass, 82.0 ± 12.6 kg; height, 177.3 ± 6.9 cm) performed bilateral leg press and knee extensions (5 sets of 10 repetitions at 80% of 1 repetition maximum, 2 minutes rest). Participants completed 1 trial in a euhydrated state (EUH; urine specific gravity [USG] < 1.020) and the other trial in a dehydrated state (DEH: USG ≥ 1.020), which was separated by 2 weeks. For the DEH trial, participants were restricted from consuming fluids for 24 hours before RE and were only permitted to drink 1.5 L of water after RE for the remainder of the day. For the EUH trial, participants were instructed to consume fluid for 24 hours before and 24 hours after RE to maintain euhydration. Sleep and recovery measurements were collected from a wearable sleep device that participants wore the night before (PRE) and after RE (POST). Repeated measures ANOVAs and linear mixed effect models were used to identify differences between EUH and DEH. Plasma osmolality, urine osmolality, USG, urine color, and body mass loss (p < 0.05) were significantly higher in DEH than in EUH. However, there were no differences between EUH and DEH in sleep duration, efficiency, disturbance, deprivation, slow wave sleep, rapid eye movement sleep, light sleep, awaking time, resting heart rate, and heart rate variability. In conclusion, acute dehydration might not affect sleep and recovery measurements the night before and after heavy resistance exercise.