Background/Objectives: Sleep and recovery are critical for optimising exercise performance. However, the efficacy of melatonin supplementation in improving sleep quality and next-day physical performance remains unclear. This study examined the effects of melatonin ingestion on sleep and performance-related outcomes the following day in trained males. Methods: In a randomised, double-blind, placebo-controlled crossover study, 12 trained males (age: 21.92 ± 2.84 years) ingested 6 mg of melatonin (MEL) or a placebo (PLA) the night before performing the 5 m shuttle test (5mSRT). Before and after the 5mSRT, blood samples were collected. Peak heart rate (HR_peak) and rating of perceived exertion (RPE) were recorded throughout the test. Perceived recovery status (PRS) and delayed onset muscle soreness (DOMS) were measured before, 5 min, 24 h, 48 h, and 72 h after the test. The sleep/wake cycle was monitored during the night after ingestion. Results: Data were analysed using paired t-tests, Wilcoxon tests, and two-way ANOVAs, with significance set at p < 0.05. Compared to PLA, MEL did not modify any sleep parameters or blood markers (all p > 0.05). However, MEL improved total distance, fatigue index, the percentage decrement between sprints, and HR_peak (all p < 0.05) in the 5mSRT compared to PLA. MEL also enhanced PRS values up to 72 h post-exercise and reduced DOMS (all p < 0.05). Conclusion: In summary, 6 mg of melatonin taken at night enhanced next-day high-intensity exercise performance and improved perceived recovery up to 72 h post-exercise.

Background/Objectives: Creatine monohydrate (CrM) supplementation is well-established for enhancing physical performance and accelerating recovery in several sporting contexts. However, beyond these traditional performance benefits, its effects on sleep metrics and cognitive function have not been thoroughly investigated. This investigation aimed to determine the effect of a loading phase of CrM on sleep metrics, physical performance, psycho-cognitive aspects, and recovery in physically active men. Methods: In a randomized, double-blind, placebo-controlled crossover design, 14 physically active men ingested 20 g/day of CrM or placebo (PL) for 7 days, during which their habitual exercise routines were maintained and standardized across both intervention phases. Sleep metrics were monitored throughout the interventions using wrist-worn actigraphy. On the day following the completion of each supplementation phase, participants rated their sleep quality using the Sleep Subjective Quality (SSQ) scale, and the Hooper questionnaire was used to monitor participants’ well-being status. Physical performance was assessed using the 5 m shuttle run test (5mSRT), which measured total distance (TD), best distance (BD), performance decrement (PD), fatigue index (FI), and the rating of perceived exertion (RPE). Affective valence was determined using the feeling scale (FS) and cognitive function was evaluated using the digit cancellation test (DCT). Recovery and muscle soreness perceptions were evaluated at multiple time points (pre-exercise, 5 min, 24 h, 48 h, and 72 h post-exercise) using the perceived recovery status (PRS) and the delayed onset muscle soreness (DOMS) scales, respectively. Results: During the supplementation, CrM improved sleep quality compared to PL, as measured with the SSQ scale (d = 0.81, p = 0.009), and was associated with an earlier in-bed time (r = 0.60; p = 0.026). However, CrM did not affect sleep latency (t = 0.98; p = 0.35), sleep efficiency (t = 0.018; p = 0.98), or total sleep time (t = 0.25; p = 0.81). After the supplementation phase, CrM resulted in significantly lower muscle soreness scores, as measured by the Hooper questionnaire (d = −0.59; p = 0.046), improved cognitive performance on the DCT (d = 0.77; p = 0.013), and enhanced TD (r = 0.88; p < 0.001) and BD (r = 0.76; p < 0.05) during the 5mSRT. However, CrM did not significantly affect other exercise-related measures such as RPE, fatigue index (FI), or performance decrement (PD) during the 5mSRT, nor did it alter other subjective recovery scales compared to PL, up to 72 h following the end of the supplementation phase (all p > 0.05). Conclusions: A 7-day CrM loading protocol improved subjective sleep quality during the supplementation phase, enhanced cognitive performance, and increased physical output during high-intensity intermittent exercise. CrM also reduced muscle soreness, but did not significantly affect objective sleep parameters, or recovery markers up to 72 h post-exercise. These findings suggest that CrM may offer additional benefits beyond its traditional ergogenic role. Trial Registration: This trial was registered on 18 September 2023 at the Pan African Clinical Trials Registry (PACT) (identifier: PACTR202309597156293).

Background/Objectives: Melatonin (MEL) promotes sleep and recovery, while caffeine (CAF) enhances alertness and performance. Despite their common use among athletes, their potential interaction remains underexplored. This study examined the effects of MEL and CAF, administered separately or in combination, on sleep, physical performance, physiological, biochemical, and perceptual responses in trained males. Methods: In a randomized double-blind placebo-controlled crossover study, fourteen trained males (22.4 ± 2.9 years) underwent four conditions, designed to isolate the effects of each substance and their interaction: (1) PLA + PLA: placebo before sleep and placebo in the morning; (2) PLA + CAF: placebo before sleep and caffeine (3 mg·kg⁻¹) in the morning; (3) MEL + PLA: melatonin (6 mg) before sleep and placebo in the morning; and (4) MEL + CAF: melatonin before sleep followed by caffeine in the morning. One hour after the morning ingestion, participants performed the 5 m shuttle run test (5mSRT). Blood samples were collected pre- and post-exercise to assess markers of muscle damage (creatine kinase, lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase) and inflammation (C-reactive protein). Peak heart rate (HR_peak) and rating of perceived exertion (RPE) were recorded throughout the test. Sleep was assessed only during the night following melatonin or placebo ingestion. Results: No differences were observed in sleep parameters between conditions (p > 0.05). Total distance in the 5mSRT increased following MEL + CAF and PLA + CAF conditions compared with PLA + PLA. Moreover, MEL + CAF reduced muscle damage and inflammation markers compared with PLA + PLA, MEL + PLA, and PLA + CAF conditions (p < 0.05). Conclusions: The ingestion of nocturnal MEL and next-day CAF was associated with improvements in certain high-intensity exercise performance outcomes, along with changes in muscle damage and inflammation.

Background/Objectives: Although creatine (Cr) supplementation is well established for enhancing strength exercise adaptations, limited evidence exists regarding whether the timing of a single Cr dose relative to exercise acutely influences performance and related physiological and perceptual responses. This study examined whether the timing of a single dose of Cr ingestion relative to a strength exercise session influences acute strength and power performance, cognitive function, perceptual responses, and selected blood biomarkers in physically active men. Methods: In a randomized, placebo-controlled crossover design, 11 physically active men (26.09 ± 4.39 years) completed five experimental conditions: Cr ingested before exercise (CrB), during exercise (CrD), and after exercise (CrF), placebo (PL), and a no-supplement control. Participants ingested 0.1 g·kg⁻¹ body mass of monohydrate Cr or placebo. Each condition included a standardized strength training session, where bench press (BP) and back squat (BSQ) performance was assessed as the total external load lifted (kg) across six sets performed at 80% of 1-RM for each exercise. Countermovement jump (CMJ) performance, Profile of Mood States (POMS), cognitive performance (digit cancelation test), perceived exertion (RPE), perceived recovery scale (PRS), Delayed-Onset Muscle Soreness (DOMS), and blood markers of muscle damage and renal function were assessed after the resistance training session. Data were analyzed using repeated-measures ANOVA or non-parametric equivalents, with post hoc comparisons adjusted for multiple testing. Results: There was a significant main effect of condition for both BP (F = 4.91, ηp² = 0.33, p = 0.035) and BSQ performance (F = 33.22, ηp² = 0.77, p < 0.001), with greater performance under the CrB condition compared with PL and control (p < 0.05). A significant effect of condition was also observed for creatine kinase (χ² (4) = 12.22, p = 0.016) and creatinine concentrations (χ² (4) = 17.75, p = 0.001). Blood creatine kinase concentrations were greater under CrF conditions than control (p = 0.013) and PL (p = 0.041). Moreover, creatinine concentration was lower under the CrB condition compared to CrD (p = 0.033), CrF (p = 0.003), and the control (p = 0.021). No differences were observed for CMJ performance, cognitive performance, POMS, RPE, PRS, DOMS, or the remaining biochemical markers across treatments. Conclusions: Pre-exercise creatine ingestion (without loading phase) was associated with greater acute strength performance compared with other timing conditions. However, the findings are exploratory and have to be confirmed with a higher sample size and robust placebo/control structures.

Napping is recognized as a strategy to enhance athletic performance. However, the optimal timing and duration for maximizing its benefits remain unclear. This study investigated the effects of a 90 min nap at different times on physical performance, psycho-cognitive responses, and perceived recovery in trained youth male athletes. Fourteen athletes (18 ± 1 years) completed four conditions in a randomized crossover design: (1) No-nap-13h, (2) No-nap-15h, (3) Nap-13h, and (4) Nap-15h. After each condition, athletes performed a 5 m shuttle run test (5mSRT) and were assessed on best distance (BD), total distance (TD), and fatigue index (FI). Ratings of perceived exertion (RPE) were recorded after each 5mSRT repetition, whereas muscle soreness (DOMS) and recovery (PRS) were assessed post-test and 24 h later. The digit cancelation test (DCT), feeling scale (FS), Stanford Sleepiness Scale (SSS), and Hooper Questionnaire evaluated sleep quality and psycho-cognitive state. Results showed that the athletes felt greater sleepiness before Nap-15h and after Nap-13h versus the no-nap conditions. TD was higher in Nap-13h than Nap-15h (p = 0.001) and No-nap-15h (p = 0.0009). BD was higher in Nap-13h versus No-nap-15h and No-nap-13h, while RPE was higher in Nap-13h versus No-nap-13 h, Nap-15h, and No-nap-15h (all, p < 0.05). DCT scores were also higher in Nap-13h. No significant effects were found for FI, FS, or Hooper. In conclusion, a 90 min nap at 13:00 was more effective than a later nap or no nap in improving performance and recovery, suggesting benefits for afternoon training or competitions.