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Background: The aim of this study was to evaluate the effect of two types of partial sleep deprivation (PSD) on biomarkers of muscle and cardiac injuries in response to acute intermittent exercise in professional athletes., Methods: In a counterbalanced order, ten healthy male Taekwondo athletes were asked to perform the Yo-Yo Intermittent Recovery Test (YYIRT) in three conditions, allowing a 36 h recovery period in between: 1) following a full night of habitual sleep known as a reference sleep night (RN); 2) following PSD in the beginning of the night (PSDBN); and 3) following PSD in the end of the night (PSDEN). Heart rate (HR) and arterial oxygen saturation (SaO2) were measured during exercise. Blood samples were taken just before and 3 min after the YYIRT to measure biomarkers related to muscle and cardiac injuries (BRMCI)., Results: No significant effect of PSD was observed for physiological parameters (i.e., HR and SaO2). However, a significant alteration of resting ultra-sensitive C-reactive protein (us-CRP) (P<0.05) and myoglobin (MYO) (P<0.01) levels was detected after PSDEN. Furthermore, all BRMCI were altered by exercise. Likewise, compared to RN, PSD affected creatine phosphokinase (CPK) and MYO levels in response to exercise (P<0.05)., Conclusions: The present study indicates that PSDEN increase the resting us-CRP and MYO levels, and that the two types of PSD increase the CPK and MYO levels in response to acute intermittent exercise, among Taekwondo athletes, in the evening of the following day. However, no rise of the physiological responses has been observed after the two types of PSD, at rest and in response to the exercise.

Background: The present study aimed to investigate the concomitant effects of Ramadan intermittent fast (RIF) and muscle fatigue on neuromuscular performances and reaction times in young trained athletes., Methods: Eight karate players (17.2 ± 0.5 years) were tested on three sessions: during a control period (S1: one week before Ramadan), and during the first (S2) and the fourth week of RIF (S3). Dietary intake and anthropometric measurements were assessed before each session. During each test session, participants performed maximal voluntary isometric contractions (MVC) and a submaximal contraction at 75 % MVC until exhaustion (T lim ) of the right elbow flexors. Surface electromyography was recorded from biceps brachii muscle during MVC and T lim . Simple (SRT) and choice (CRT) reaction times were evaluated at rest and just after T lim in a random order., Results: The total daily energy (S2: +19.5 %, p < 0.05; S3: +27.4 %, p < 0.01) and water (S2: +26.8 %, p < 0.01; S3: +23.2 %, p < 0.05) intake were significantly increased during RIF. However, neither body mass nor body mass index was altered by RIF (F (2,14) = 0.80, p = 0.47 and F (2,14) = 0.78, p = 0.48, respectively). In addition, T lim (F (2,14) = 2.53, p = 0.12), MVC (F (2,14) = 0.51, p = 0.61) and associated electrical activity (F (2,14) = 0.13, p = 0.88) as well as neuromuscular efficiency (F (2,14) = 0.27, p = 0.76) were maintained during RIF. Moreover, neither SRT nor CRT was affected by RIF (F (2,14) = 1.82, p = 0.19 and F (2,14) = 0.26, p = 0.78, respectively) or neuromuscular fatigue (F (1,7) = 0.0002, p = 0.98 and F (1,7) = 3.78, p = 0.09, respectively)., Conclusions: The present results showed that RIF did not adversely affect the neuromuscular performances and anthropometric parameters of elite karate athletes who were undertaking their usual training schedule. In addition, neither RIF nor neuromuscular fatigue poorly affects reaction times in elite karate athletes.

Background: Inconsistent sleep schedules, frequent awakening after sleep onset (WASO), and decreased sleep efficiency (SE) are common issues among adolescent team sports athletes. Moreover, research indicates that sleep problems are enhanced across schooldays. The aim of the present study was to assess sleep patterns of adolescent athletes and compare sleep parameters between schooldays and holidays. Methods: The chronotype and sleep quality of twelve adolescent basketball players (mean age: 15.58 ± 0.67 years) were assessed. Objective sleep parameters were then analyzed using actigraphy over a 12-day period, which included six days during the school period and six days during holidays. Results: Data showed that total sleep time (TST), SE, and WASO (382.48 min, 81.81%, and 66.70 min, respectively) did not meet international recommendations for sleep quantity and quality. During school weekdays, time in bed (TIB), TST, and SE significantly decreased compared to weekends (p < 0.001, d = −1.49; p < 0.001, d = −1.64; and p = 0.01, d = −0.89, respectively). On weekdays, TIB, TST, and WASO were significantly lower on schooldays compared to holidays (p < 0.001, d = −1.83; p < 0.01, d = −1.01; and p = 0.02, d = −0.77, respectively). While no significant difference was observed in social jetlag, the mid-point of sleep was significantly later on holiday weekdays compared to school weekdays (p < 0.05, d = 0.65). Conclusions: Adolescent athletes experience insufficient sleep, especially on school weekdays, which is partially improved during weekends and holidays. Although sleep duration was longer during holidays, our results suggest that adolescent athletes' sleep was more fragmented. Consequently, it remains crucial to implement strategies to enhance their sleep health (e.g., napping). [ABSTRACT FROM AUTHOR]

Sleep and autonomic nervous system (ANS) influence each other in a bidirectional fashion. Importantly, it has been proposed that sleep has a beneficial regulatory influence over cardiovascular activity, which is mostly controlled by autonomic regulation through the activity of sympathetic and parasympathetic pathways of the ANS. A well-established method to non-invasively assess cardiac autonomic activity is heart rate variability (HRV) analysis. We aimed to investigate the effect of a 40-min nap opportunity on HRV. Twelve professional basketball players randomly accomplished two conditions: 40-min nap (NAP) and control (CON). Nocturnal sleep and naps were monitored by actigraphic recording and sleep diaries. Total sleep time (TST), time in bed (TIB), sleep efficiency (SE), sleep onset latency (SOL), and wake after sleep onset (WASO) were analyzed. HRV was analyzed in 5-min segments during quiet wake before and after each condition with controlled breathing. Were analysed high (HF) and low frequency (LF) bands, the standard deviation of NN interval (SDNN), HRV index and stress index (SI). Wellness Hooper index and Epworth Sleepiness Scale (ESS) were assessed before and after both conditions. There was no significant difference in TIB, TST, SE, WASO, and VAS between NAP and CON. A significant increase in SDNN, HRV index, and LF and a significant decrease in HF, SI, ESS, and Hooper's stress and fatigue scores were observed from pre- to post-nap. In conclusion, napping reduces sleepiness, stress and fatigue, and might provide an advantage by preparing the body for a muchrequired sympathetic comeback following peaceful rest. [ABSTRACT FROM AUTHOR]

The effect of a 40-min nap opportunity on physiological responses and specific abilities was investigated. Twelve high-level professional basketball players (26.33±5.2 years; 193.17±7.1 m; 87.48±11.2 kg) undertook randomly 40-min nap opportunity (NAP) and control condition (CON). Wellness (Hooper Index) and Epworth Sleepiness Scale (ESS) were measured before and after both conditions. Defensive (DA) and offensive (OA) agility and upper body power (UBP) were assessed after both conditions. Shooting skill (SST) performance was evaluated prior and after a fatiguing task (FT). Heart rate (HR) and rating of perceived exertion (RPE) were recorded during SST-test, FT and SST-retest. ESS, Hooper's stress and fatigue score were significantly lower after nap compared to those before nap (0.009 ≤ p ≤ 0.03). Better performance was obtained in NAP compared to CON condition for DA, OA and UBP (0.0005 ≤ p ≤ 0.02). SST performance was significantly higher in NAP compared to CON in the retest session (p = 0.003, Δ = 20.2%). The improved performance was associated with significant lower HRpeak (p = 0.01, Δ = 5.25%) and RPE (p = 0.003, Δ = 15.12%). In conclusion, NAP reduced sleepiness and stress and fatigue and enhances physical outcomes of specific skills in elite basketball players. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effects of napping after partial sleep deprivation (PSD) on reaction time, mood, and biochemical response to repeated-sprint exercise in athletes. Methods: Nine male judokas performed 4 test sessions in a counterbalanced and randomized order. Participants accomplished 1 control session after a normal sleep night (NSN) and 3 after PSD with (1) no nap, (2) -20-min nap (N20), and (3) -90-min nap (N90) opportunities. Test sessions included the running-based anaerobic sprint test, reaction time, Hooper index, and Epworth Sleepiness Scale. Muscle-damage biomarkers and antioxidant status were evaluated before and after exercise. Results: PSD decreased maximum (P < .001, d = 1.12), mean (P < .001, d = 1.33), and minimum (P < .001, d = 1.15) powers compared with NSN. However, N20 and N90 enhanced maximum power compared with PSD (P < .05, d = 0.54; P < .001, d = 1.06, respectively). Minimum power and mean power increased only after N90 (P < .001, d = 1.63; P < .001, d = 1.16, respectively). Epworth Sleepiness Scale increased after PSD (P < .001, d = 0.86) and decreased after N20 (P < .001, d = 1.36) and N90 (P < .001, d = 2.07). N20 reduced multiple-choice reaction time (P < .001, d = 0.61). Despite performance decrement, PSD increased postexercise aspartate aminotransferase (P < .001, d = 4.16) and decreased glutathione peroxidase (P < .001, d = 4.02) compared with NSN. However, the highest performances after N90 were accompanied with lesser aspartate aminotransferase (P < .001, d = 1.74) and higher glutathione peroxidase (P < .001, d = 0.86) compared with PSD. Conclusions: Napping could be preventive against performance degradation caused by sleep loss. A short nap opportunity could be more beneficial when the subsequent effort is brief and requires frequent decision making. However, a longer nap opportunity could be preventive against muscle and oxidative damage, even for higher performances. [ABSTRACT FROM AUTHOR]

Objective: To investigate the effect of 1) lockdown duration and 2) training intensity on sleep quality and insomnia symptoms in elite athletes. Methods: 1,454 elite athletes (24.1 ± 6.7 years; 42% female; 41% individual sports) from 40 countries answered a retrospective, cross-sectional, web-based questionnaire relating to their behavioral habits pre- and during- COVID-19 lockdown, including: 1) Pittsburgh sleep quality index (PSQI); 2) Insomnia severity index (ISI); bespoke questions about 3) napping; and 4) training behaviors. The association between dependent (PSQI and ISI) and independent variables (sleep, napping and training behaviors) was determined with multiple regression and is reported as semi-partial correlation coefficient squared (in percentage). Results: 15% of the sample spent < 1 month, 27% spent 1–2 months and 58% spent > 2 months in lockdown. 29% self-reported maintaining the same training intensity during-lockdown whilst 71% reduced training intensity. PSQI (4.1 ± 2.4 to 5.8 ± 3.1; mean difference (MD): 1.7; 95% confidence interval of the difference (95% CI): 1.6–1.9) and ISI (5.1 ± 4.7 to 7.7 ± 6.4; MD: 2.6; 95% CI: 2.3–2.9) scores were higher during-compared to pre-lockdown, associated (all p < 0.001) with longer sleep onset latency (PSQI: 28%; ISI: 23%), later bedtime (PSQI: 13%; ISI: 14%) and later preferred time of day to train (PSQI: 9%; ISI: 5%) during-lockdown. Those who reduced training intensity during-lockdown showed higher PSQI (p < 0.001; MD: 1.25; 95% CI: 0.87–1.63) and ISI (p < 0.001; MD: 2.5; 95% CI: 1.72–3.27) scores compared to those who maintained training intensity. Although PSQI score was not affected by the lockdown duration, ISI score was higher in athletes who spent > 2 months confined compared to those who spent < 1 month (p < 0.001; MD: 1.28; 95% CI: 0.26–2.3). Conclusion: Reducing training intensity during the COVID-19-induced lockdown was associated with lower sleep quality and higher insomnia severity in elite athletes. Lockdown duration had further disrupting effects on elite athletes' sleep behavior. These findings could be of relevance in future lockdown or lockdown-like situations (e.g., prolonged illness, injury, and quarantine after international travel). [ABSTRACT FROM AUTHOR]

Background: Evidence suggests that athletes often experience chronic sleep disturbance. Napping is widely recommended as a safe and non-invasive intervention to counteract the negative effects of partial sleep deprivation. However, systematic reviews on the benefits of napping have yet to be undertaken. Objective: (i) To evaluate the effectiveness of diurnal napping opportunities on athletes' physical and cognitive performance and (ii) to outline how aspects of the study design (i.e., nap duration, exercise protocol, participants' fitness level and previous sleep quantity) can influence the potential effects of napping through a systematic appraisal of the literature. Methods: This systematic review was conducted in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. PubMed, Web of Science and SCOPUS databases were searched up to June 2020 for relevant studies investigating the effect of napping on physical and cognitive performances in physically active participants. Fourteen strong-quality and four moderate-quality (mean QualSyst score = 75.75 ± 5.7%) studies met our inclusion criteria and were included in the final sample (total participants: 158 physically active and 168 athletes). Results: Most studies (n = 15) confirmed the beneficial effects of napping and showed that diurnal napping improved short-term physical performance (n = 10), endurance performance (n = 3) and specific skills performance (n = 2). Two studies showed no significant napping effect and only one study showed reduced sprint performance following diurnal napping. Moreover, napping improved reaction time (n = 3), attention (n = 2) and short-term memory (n = 1) performances. Importantly, "replacement naps" improved both physical and cognitive performance regardless of the type of exercise. However, "prophylactic naps" improved only jump, strength, running repeated-sprint, attention and reaction time performances. In addition, this systematic review revealed that longer nap opportunities (i.e., 90 min) resulted in better improvement of physical and cognitive performance and lower induced fatigue. Conclusions: A diurnal nap seems to be an advantageous intervention to enhance recovery process and counteract the negative effect of partial sleep deprivation on physical and cognitive performance. Particularly, to optimize physical performances of athletes experiencing chronic lack of sleep, findings from the included individual studies suggest 90 min as the optimal nap duration. Diurnal napping may be beneficial for athletes but this benefit should be viewed with caution due to the quality of the evidence, risk of bias and the limited evidence about napping interventions. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effects of placebo (PLA), 20 min nap opportunity (N20), 5mg·kg−1 of caffeine (CAF), and their combination (CAF+N20) on sleepiness, mood and reaction-time after partial sleep deprivation (PSD; 04h30 of time in bed; study 1) or after normal sleep night (NSN; 08h30 of time in bed; study 2). Methods: Twenty-three highly trained athletes (study 1 ; 9 and study 2 ; 14) performed four test sessions (PLA, CAF, N20 and CAF+N20) in double-blind, counterbalanced and randomized order. Simple (SRT) and two-choice (2CRT) reaction time, subjective sleepiness (ESS) and mood state (POMS) were assessed twice, pre- and post-intervention. Results: SRT was lower (i.e., better performance) during CAF condition after PSD (pre: 336 ± 15 ms vs. post: 312 ± 9 ms; p < 0.001; d = 2.07; Δ% = 7.26) and NSN (pre: 350 ± 39 ms vs. post: 323 ± 32 ms; p < 0.001; d = 0.72; Δ% = 7.71) compared to pre-intervention. N20 decreased 2CRT after PSD (pre: 411 ± 13 ms vs. post: 366 ± 20 ms; p < 0.001; d = 2.89; Δ% = 10.81) and NSN (pre: 418 ± 29 ms vs. post: 375 ± 40 ms; p < 0.001; d = 1.23; Δ% = 10.23). Similarly, 2CRT was shorter during CAF+N20 sessions after PSD (pre: 406 ± 26 ms vs. post: 357 ± 17 ms; p < 0.001; d = 2.17; Δ% = 12.02) and after NSN (pre: 386 ± 33 ms vs. post: 352 ± 30 ms; p < 0.001; d = 1.09; Δ% = 8.68). After PSD, POMS score decreased after CAF (p < 0.001; d = 2.38; Δ% = 66.97) and CAF+N20 (p < 0.001; d = 1.68; Δ% = 46.68). However, after NSN, only N20 reduced POMS (p < 0.001; d = 1.05; Δ% = 78.65) and ESS (p < 0.01; d = 0.71; Δ% = 19.11). Conclusion: After PSD, all interventions reduced sleepiness and only CAF enhanced mood with or without napping. However, only N20 enhanced mood and reduced sleepiness after NSN. Caffeine ingestion enhanced SRT performance regardless of sleep deprivation. N20, with or without caffeine ingestion, enhanced 2CRT independently of sleep deprivation. This suggests a different mode of action of napping and caffeine on sleepiness, mood and reaction time. [ABSTRACT FROM AUTHOR]

It is well established that intensive physical training induces oxidative stress and muscle damage that can contribute to fatigue and injuries. Melatonin (MEL) has been used as an ergogenic aid (i.e. antioxidant, chronobiotic, and anti-inflammatory) which could help athletes during an intensive training period. The present study aimed to evaluate the effect of MEL supplementation on the recovery of physical performance, muscle pain and biochemical responses after an intensive training camp (TC). Twenty soccer players, volunteered to participate in this study, performed a repeated sprint ability (RSA) test before and after an intensive six-days TC with a daily ingestion of MEL or placebo. Resting and post RSA test blood samples were taken before and after the TC. MEL intake decreased resting oxidative stress marker (i.e. MDA) (p < 0.05), and biomarkers of muscle damage (i.e. CK, LDH) (p < 0.05). It increased the activity of the main antioxidant enzyme (i.e. SOD) (p < 0.05). MEL also helped to reduce the drop in performance observed after the TC (p < 0.05) and decreased muscle pain (p < 0.05). In conclusion, MEL supplementation during an intensive TC alleviates oxidative stress and muscle damage and improved the recovery of physical performance in soccer players. [ABSTRACT FROM AUTHOR]

The present study aimed to explore the effects of a single 10-mg dose of melatonin (MEL) administration after exhaustive late-evening exercise on sleep quality and quantity, and short-term physical and cognitive performances in healthy teenagers. Ten male adolescent athletes (mean ± SD, age = 15.4 ± 0.3 years, body-mass = 60.68 ± 5.7 kg, height = 167.9 ± 6.9 cm and BMI = 21.21 ± 2.5) performed two test sessions separated by at least one week. During each session, participants completed the Yo-Yo intermittent-recovery-test level-1 (YYIRT-1) at ~20:00 h. Then, sleep polysomnography was recorded from 22:15 min to 07:00 h, after a double blind randomized order administration of a single 10-mg tablet of MEL (MEL-10 mg) or Placebo (PLA). The following morning, Hooper wellness index was administered and the participants performed the Choice Reaction Time (CRT) test, the Zazzo test and some short-term physical exercises (YYIRT-1, vertical and horizontal Jumps (VJ; HJ), Hand grip strength (HG), and five-jump test (5-JT)). Evening total distance covered in the YYIRT-1 did not change during the two conditions (p > 0.05). Total sleep time (Δ = 24.55 mn; p < 0.001), sleep efficiency (Δ = 4.47%; p < 0.001), stage-3 sleep (N3 sleep) (Δ = 1.73%; p < 0.05) and rapid-eye-movement sleep (Δ = 2.15%; p < 0.001) were significantly higher with MEL in comparison with PLA. Moreover, sleep-onset-latency (Δ = -8.45mn; p < 0.001), total time of nocturnal awakenings after sleep-onset (NA) (Δ = -11 mn; p < 0.001), stage-1 sleep (N1 sleep) (Δ = -1.7%; p < 0.001) and stage-2 sleep (N2 sleep) (Δ = −1.9%; p < 0.05) durations were lower with MEL. The Hooper index showed a better subjective sleep quality, a decrease of the subjective perception of fatigue and a reduced level of muscle soreness with MEL. Moreover, MEL improved speed and performance but not inaccuracy during the Zazzo test. CRT was faster with MEL. Morning YYIRT-1 (Δ = 82 m; p < 0.001) and 5-JT (Δ = 0.08 m; p < 0.05) performances were significantly higher with MEL in comparison with PLA. In contrast, HG, VJ and HJ performances did not change during the two conditions (p > 0.05). The administration of a single dose of MEL-10 mg after strenuous late-evening exercise improved sleep quality and quantity, selective attention, subjective assessment of the general wellness state, and some short-term physical performances the following morning in healthy teenagers. [ABSTRACT FROM AUTHOR]

Purpose: To verify whether active recovery (AR) applied after a kickboxing match resulted in better performance in anaerobic tests when compared to passive recovery (PR). Methods: Eighteen kickboxers volunteered to participate on a Kickboxing match preceded and followed by anaerobic tests: squat jump (SJ), the counter movement jump (CMJ) and the upper-body Wingate test. Blood lactate (BL), heart rate (HR) and rate of perceived exertion (RPE) were analyzed before and after rounds. The recovery sessions consisted of 10min at 50% of maximal aerobic speed or PR. BL was measured at 3, 5 and 10 min after the match, while HR, RPE and anaerobic power were assessed after the recovery period. Results: BL, HR and RPE increased significantly (P<0.001) during the match. BL was lower (P<0.001) after AR compared to PR at 5 min and 10 min (e.g. AR: 8.94 ± 0.31 mmol.l-1, PR: 10.98 ± 0.33 mmol.l-1). However, PR resulted in higher (P<0.05) upper-body mean power (4.65 ± 0.5 W.kg-1) compared to AR (4.09 ± 0.5 W.kg-1), while SJ and CMJ were not affected by the recovery type. Conclusion: The lactate removal was improved with AR when compared with PR, but AR did not improve subsequent performance. [ABSTRACT FROM AUTHOR]

Purpose: To verify whether active recovery (AR) applied after a kickboxing match resulted in better performance in anaerobic tests when compared to passive recovery (PR). Methods: Eighteen kickboxers volunteered to participate on a Kickboxing match preceded and followed by anaerobic tests: squat jump (SJ), the counter movement jump (CMJ) and the upper-body Wingate test. Blood lactate (BL), heart rate (HR) and rate of perceived exertion (RPE) were analyzed before and after rounds. The recovery sessions consisted of 10min at 50% of maximal aerobic speed or PR. BL was measured at 3, 5 and 10 min after the match, while HR, RPE and anaerobic power were assessed after the recovery period. Results: BL, HR and RPE increased significantly (P<0.001) during the match. BL was lower (P<0.001) after AR compared to PR at 5 min and 10 min (e.g. AR: 8.94 ± 0.31 mmol.l-1, PR: 10.98 ± 0.33 mmol.l-1). However, PR resulted in higher (P<0.05) upper-body mean power (4.65 ± 0.5 W.kg-1) compared to AR (4.09 ± 0.5 W.kg-1), while SJ and CMJ were not affected by the recovery type. Conclusion: The lactate removal was improved with AR when compared with PR, but AR did not improve subsequent performance. [ABSTRACT FROM AUTHOR]

There is a conflict in the literature with regard to effects of the Ramadan intermittent fasting (RIF) on body composition and neuromuscular performance. The purpose of this pilot study was to examine the effect of the RIF on body mass/composition and neuromuscular performance during maximal voluntary contraction (MVC) and a muscle endurance exercise (Tlim) of the knee extensors. Eight adolescents (17.2 ± 0.5 years) karate players were tested. Anthropometric variables (i.e. body mass, body mass index, fat mass and lean body mass) were evaluated 7 days before Ramadan (T1), and on days 7 (T2) and 28 (T3) of Ramadan. Each subject performed three MVC and aTlimat 75% of MVC at T1, T2, and T3. Surface electromyographic (EMG) activity of vastus lateralis and vastus medialis was recorded during these neuromuscular tests. The anthropometric variables were unaltered by RIF. Likewise, there was no significant effect of RIF on the MVC (P = 0.29) and theTlim(P = 0.22). This result was in accordance with the absence of change in both EMG activity level during MVC and in the rate of changes in EMG parameters (EMG activity level and frequency content) duringTli m. The results of the present study suggest that RIF does not impair maximal force generating capacity and muscle endurance at 75% of MVC. Therefore, Muslim experienced athletes could maintain their neuromuscular performance level by undertaking usual training loads during RIF. [ABSTRACT FROM PUBLISHER]