Sleep quality and high intensity interval training at two different times of day: A crossover study on the influence of the chronotype in male collegiate soccer players

Time-restricted eating, the clock ticking behind the scenes

Introduction

Maintaining metabolic balance relies on accumulating nutrients during feeding periods and their subsequent release during fasting. In obesity and metabolic disorders, strategies aimed at reducing food intake while simulating fasting have garnered significant attention for weight loss. Caloric restriction (CR) diets and intermittent fasting (IF) interventions have emerged as effective approaches to improving cardiometabolic health. Although the comparative metabolic benefits of CR versus IF remain inconclusive, this review focuses on various forms of IF, particularly time-restricted eating (TRE).

Methods

This study employs a narrative review methodology, systematically collecting, synthesizing, and interpreting the existing literature on TRE and its metabolic effects. A comprehensive and unbiased search of relevant databases was conducted to identify pertinent studies, including pre-clinical animal studies and clinical trials in humans. Keywords such as "Obesity," "Intermittent Fasting," "Time-restricted eating," "Chronotype," and "Circadian rhythms" guided the search. The selected studies were critically appraised based on predefined inclusion and exclusion criteria, allowing for a thorough exploration and synthesis of current knowledge.

Results

This article synthesizes pre-clinical and clinical studies on TRE and its metabolic effects, providing a comprehensive overview of the current knowledge and identifying gaps for future research. It explores the metabolic outcomes of recent clinical trials employing different TRE protocols in individuals with overweight, obesity, or type II diabetes, emphasizing the significance of individual chronotype, which is often overlooked in practice. In contrast to human studies, animal models underscore the role of the circadian clock in mitigating metabolic disturbances induced by obesity through time-restricted feeding (TRF) interventions. Consequently, we examine pre-clinical evidence supporting the interplay between the circadian clock and TRF interventions. Additionally, we provide insights into the role of the microbiota, which TRE can modulate and its influence on circadian rhythms.

The optimal exercise intervention for sleep quality in adults: A systematic review and network meta-analysis

BACKGROUND

The impact of various exercise modalities on the improvement of sleep quality in adults remains controversial.

OBJECTIVE

This study aimed to perform a network meta-analysis to analyze the effects of different exercise interventions on sleep quality in adults.

METHODS

The PubMed, Cochrane, Embase, Web of Science, and EBSCO databases were searched for studies published from March 18, 1993, to March 18, 2023. The Cochrane risk of bias tool was used to assess the quality of the included studies. Then, a random-effects network meta-analysis was conducted within a frequentist framework.

RESULTS

A total of 2142 participants from 27 randomized controlled trials were included in the analysis. Exercise modalities such as Pilates, yoga, and traditional Chinese exercises were found to significantly improve sleep quality when compared to a no-exercise control group, with Pilates exhibiting the most potent effect at a 95.3% improvement level.

CONCLUSION

This study demonstrates that exercise interventions are effective in enhancing sleep quality in adults. Adapting exercise to individual preferences and needs may maximize the sleep-related benefits of the activity.

REGISTRATION

The review was registered with PROSPERO, registration number CRD42023434565.

Small-Sided Soccer Games Promote Greater Adaptations on Vertical Jump and Change-of-Direction Deficit and Similar Adaptations in Aerobic Capacity than High-Intensity Interval Training in Females

The objective of this study was to compare the effectiveness of both small-sided games (SSG) and short interval running-based high-intensity interval training (HIIT) programs over an 8-week period in fostering adaptations in aerobic capacity, change-of-direction abilities, and jumping performances of youth female soccer players. The study involved 48 female youth participants under the age of 19, competing at the regional level, who took part in a randomized controlled trial. Participants were assigned to either the SSG group, the HIIT group, or a control group, which involved regular in-field sessions. Assessments were conducted at baseline and after the 8-week training intervention, measuring aerobic capacity using the 30-15 intermittent fitness test (VIFT), change of direction (COD) using the 5-0-5 test, and jumping performance using the countermovement jump test (CMJ). Time 5 group analysis revealed significant interactions in CMJ (p = 0.005; ηp2= 0.213) and VIFT (p < 0.001; ηp2 = 0.433), although no significant interaction were found in COD deficit (p = 0.246; ηp2 = 0.060). Within-group analysis revealed that SSG significantly improved CMJ (p < 0.001), COD deficit (p < 0.001), and VIFT (p < 0.001). HIIT group also significantly improved CMJ (p = 0.029), COD deficit (p = 0.001), and VIFT (p < 0.001). As conclusion, the study revealed that SSG promoted significantly improvements in VIFT, CMJ and COD deficit, being significantly better than control group, while HIIT was only significantly better than control in VIFT. SSG revealed to be effective approach for favoring key physical attributes of female soccer players, being an interesting and recommended training approach to increase the ecology of the training practice, while favoring physical positive adaptations.

Interval training has more negative effects on sleep in adolescent speed skaters: a randomized cross controlled trial

Objective

Sleep is an essential component of athletic performance and recovery. This study aimed to investigate the effects of different types of high-intensity exercise on sleep parameters in adolescent speed skaters.

Methods

Eighteen male adolescent speed skaters underwent aerobic capacity testing, Wingate testing, and interval training in a randomized crossover design to assess strength output, heart rate, and blood lactate levels during exercise. Sleep quality after each type of exercise was evaluated using the Firstbeat Bodyguard 3 monitor.

Results

The results showed that Wingate testing and interval training led to decreased sleep duration, increased duration of stress, decreased RMSSD, and increased LF/HF ratio (p < 0.01). Conversely, aerobic capacity testing did not significantly affect sleep (p > 0.05). The impact of interval training on sleep parameters was more significant compared to aerobic capacity testing (p < 0.01) and Wingate testing (p < 0.01).

Conclusion

High-intensity anaerobic exercise has a profound impact on athletes' sleep, primarily resulting in decreased sleep duration, increased stress duration, decreased RMSSD, and increased LF/HF ratio.

Delaying early morning workouts to protect sleep in two-a-day athletes

Two-a-day training is common for endurance athletes with training sessions typically beginning at 6 a.m. and 3 p.m. or 4 p.m. However, the early morning workouts could contribute to significant sleep loss, especially for night owls. Chronic sleep loss over a season could result in impaired performance, as well as an increased risk of physical and mental illness. It is hypothesized that shifting the early morning workout to later in the day could have beneficial effects for these athletes. A number of obstacles could make this hypothesis difficulty to test and implement. However, such a change could have dramatic benefits for some athletes.

Adaptations to Optimized Interval Training in Soccer Players: A Comparative Analysis of Standardized Methods for Individualizing Interval Interventions

Accurately prescribing supramaximal interval training facilitates targeting desired physiological adaptations. This study compared the homogeneity of adaptations in cardiorespiratory parameters to supramaximal [i.e., intensities beyond maximal aerobic speed (MAS)] interval interventions prescribed using anaerobic speed reserve (ASR), the speed attained at the end of 30-15 Intermittent Fitness Test (VIFT), and MAS. Using repeated-measures factorial design, and during the off-season phase of the athletes' yearly training cycle, thirty national-level soccer players (age = 19 ± 1.6 years; body mass = 78.9 ± 1.6 kg; height = 179 ± 4.7 cm; Body fat = 11 ± 0.9%) were randomized to interventions consisting of 2 sets of 6, 7, 8, 7, 8, and 9-min intervals (from 1st to 6th week), including 15 s running at Δ%20ASR (MAS + 0.2 × ASR), 120%MAS, or 95%VIFT followed by 15 s passive recovery. All ASR, VIFT, and MAS programs sufficiently stimulated adaptive mechanisms, improving relative maximal oxygen uptake [V̇O2max (p < 0.05; ES = 1.6, 1.2, and 1.1, respectively)], absolute V̇O2max (p < 0.05; ES = 1.5, 1.1, and 0.7), ventilation [V̇E (p < 0.05; ES = 1.6, 1.1, and 1.1)], O2 pulse [V̇O2/HR (p < 0.05; ES = 1.4, 1.1, and 0.6)], first and second ventilatory threshold [VT1 (p < 0.05; ES = 0.7, 0.8, and 0.7) and VT2 (p < 0.05; ES = 1.1, 1.1, and 0.8)], cardiac output [Q̇max (p = 1.5, 1.0, and 0.7)], and stroke volume [SVmax (p < 0.05; ES = 0.9, 0.7, and 0.5)]. Although there was no between-group difference for the change in the abovementioned variables over time, supramaximal interval training prescribed using ASR and VIFT resulted in a lower coefficient of variation [CV (inter-individual variability)] in physiological adaptations compared to exercise intensity determined as a proportion of MAS. Expressing the intensity of supramaximal interval programs according to the athlete's ASR and VIFT would assist in accurately prescribing interventions and facilitate imposing mechanical and related physiological stimulus according to the athletes' physiological ceiling. Such an approach leads to identical stimulation across athletes with differing profiles and potentially facilitates more homogenized adaptations.

Acute evening high-intensity interval training may attenuate the detrimental effects of sleep restriction on long-term declarative memory

Recent evidence shows that a nap and acute exercise synergistically enhanced memory. Additionally, human-based cross-sectional studies and animal experiments suggest that physical exercise may mitigate the cognitive impairments of poor sleep quality and sleep restriction, respectively. We evaluated whether acute exercise may offset sleep restriction's impairment of long-term declarative memory compared to average sleep alone. A total of 92 (82% females) healthy young adults (24.6 ± 4.2 years) were randomly allocated to one of four evening groups: sleep restriction only (S5, 5-6 h/night), average sleep only (S8, 8-9 h/night), high-intensity interval training (HIIT) before restricted sleep (HIITS5), or HIIT before average sleep (HIITS8). Groups either followed a 15-min remote HIIT video or rest period in the evening (7:00 p.m.) prior to encoding 80 face-name pairs. Participants completed an immediate retrieval task in the evening. The next morning a delayed retrieval task was given after their subjectively documented sleep opportunities. Long-term declarative memory performance was assessed with the discriminability index (d') during the recall tasks. While our results showed that the d' of S8 (0.58 ± 1.37) was not significantly different from those of HIITS5 (-0.03 ± 1.64, p = 0.176) and HIITS8 (-0.20 ± 1.28, p = 0.092), there was a difference in d' compared to S5 (-0.35 ± 1.64, p = 0.038) at the delayed retrieval. These results suggest that the acute evening HIIT partially reduced the detrimental effects of sleep restriction on long-term declarative memory.

Health Professionals' Chronotype Association with Salivary Cortisol and Occupational Stress in Neonatal Intensive Care Units

Burnout syndrome has been reported among health workers, particularly those working in critical areas, and is considered a significant public health problem. This study aimed to investigate the relationship between chronotype and work-related stress, as measured by salivary cortisol levels and burnout, among health professionals working in neonatal intensive care units. A cross-sectional study was conducted across four public hospitals in Fortaleza, Ceará, Brazil. Two hundred and fifty-six health professionals were administered the brazilian version of the Burnout Characterization Scale, the morningness-eveningness questionnaire, for chronotype, a sociodemographic questionnaire that included lifestyle habits and a salivary cortisol test. The results indicated that morning chronotype workers were significantly associated with the following: advanced age (p < 0.001), female gender (p = 0.032), married status (p = 0.014), and having children (p = 0.030) compared to those with evening and intermediate chronotypes. However, no significant association was found between signs of burnout syndrome and chronotype (p = 0.316). Participants whose work shift did not match their chronotype had significantly higher initial salivary cortisol levels (p = 0.013). The findings suggest that adapting working hours to an individual's biological rhythm can help mitigate potential negative effects on physical and mental health. Thus, it is recommended that professionals' working hours be adjusted accordingly.

When should I run-the role of exercise timing in metabolic health

The prevalence of type 2 diabetes is reaching epidemic proportions. First line therapy approaches are lifestyle interventions including exercise. Although a vast amount of studies reports on beneficial effects of exercise on metabolism in humans per se, overall data are contradictory which makes it difficult to optimize interventions. Innovative exercise strategies and its underlying mechanism are needed to elucidate in order to close this therapeutic gap. The skeletal muscle produces and secretes myokines and microRNAs in response to exercise and both are discussed as mechanisms linking exercise and metabolic adaptation. Aspects of chronophysiology such as diurnal variation in insulin sensitivity or exercise as a signal to reset dysregulated peripheral clocks are of growing interest in the context of impaired metabolism. Deep insight of how exercise timing determines metabolic adaptations is required to optimize exercise interventions. This review aims to summarize the current state of research on the interaction between timing of exercise and metabolism in humans, providing insights into proposed mechanistic concepts focusing on myokines and microRNAs. First evidence points to an impact of timing of exercise on health outcome, although data are inconclusive. Underlying mechanisms remain elusive. It is currently unknown if the timed release of mykokines depends on time of day when exercise is performed. microRNAs have been found as an important mediator of processes associated with exercise adaptation. Further research is needed to evaluate their full relevance. In conclusion, it seems to be too early to provide concrete recommendations on timing of exercise to maximize beneficial effects.

Time of Day and Chronotype-Dependent Synchrony Effects Exercise-Induced Reduction in Migraine Load: A Pilot Cross-Over Randomized Trial

Migraines are the most common cause of chronic pain. Effective, non-pharmacological strategies to reduce migraine load, like exercise, are needed, but it is unclear how exercise timing and chronotype modulate the effects. We sought to determine the effects of time-of-day of exercise, and synchrony with one's chronotype, on migraine load. We performed a pilot cross-over randomized trial where participants with chronic migraine completed two one-month exercise interventions, consisting of either morning exercise (before 09:00 a.m.) or evening exercise (after 7:00 p.m.) in a randomized repeated measures cross-over design (Clinical Trial #NCT04553445). Synchrony was determined by exercise time and chronotype (i.e., a morning type participant exercising in the morning is 'in-sync,' while an evening type participant exercising in the morning is 'out-of-sync'). Migraine burden, and anthropometric assessment occurred before and after each month of exercise. Data was analyzed using repeated measures ANOVA with significance accepted at p < 0.05. When comparing morning and evening exercise, there was no significant improvements in any migraine-related parameters. However, when comparing in-sync and out-of-sync exercise, we found that migraine burden was only improved following in-sync exercise, while no benefits were seen in out-of-sync exercise. Our data suggests that exercise timing has limited impact, but synchrony with chronotype may be essential to decrease migraine load in chronic migraineurs.

Sleep regularity in athletes: Comparing sex, competitive level and sport type

This study aims to describe the athletes' sleep regularity using the Sleep Regularity Index (SRI) and determine whether factors, such as sex, competitive level and sport type, could affect the sleep/wake rhythm. It is a descriptive, cross-sectional study consisting of 172 athletes (25 ± 7 y old; 45 women). Seventy-three competed in team sports and 99 in individual sports. Furthermore, 56 competed in the international level, 95 in the national and 21 in the regional. We recorded the SRI values for at least 5 d via continuous actigraphy. We recorded a mean SRI value of 73 ± 12. We found no significant differences between athletes' sleep parameters in relation to sleep regularity. Furthermore, SRI data showed no correlations (Spearman's ρ) with sleep parameters, bed time and wake time. Female athletes (p = 0.001) and individual sport athletes (p = 0.001) reported better sleep regularity than their counterparts. International-level athletes reported better sleep regularity than those in other competitive levels (national: p = 0.001; regional: p = 0.024). Our study showed that international level athletes, female athletes and individual sport athletes reported better sleep regularity. Additionally, SRI data showed no correlation with athletes' sleep parameters, bed and wake time.

THE SPEED OF ATHLETES’ RESPONSES TO DIFFERENT TRAINING METHODS

ABSTRACT Introduction: Taekwondo is a complex reactive sport that requires training in various tactics. Due to its significant impact and antagonism, athletes must master the tactics in the shortest time. Objective: To compare the impact of password and simulation training methods on athletes’ reaction times. Methods: Taekwondo athletes› reactions and striking abilities were studied. The difference between the two training methods on taekwondo athletes’ reaction and striking ability was analyzed by comparing the data before and after the athletes’ training. Results: The mean reaction times of down kick, sidekick, and cross kick after training in the password and simulated training groups were compared, with P values of P=0.020<0.05, P=0.046<0.05, and P=0.028<0.05, respectively, showing statistical difference. In regard to the mean strike time of down kick, sidekick, and cross kick, a comparison of the password training group and the simulated training group resulted in P=0.950>0.05, P=0.417>0.05, P=0.552>0.05, respectively, with no significant statistical difference. Conclusions: The password training method is significantly better than the simulation training method for improving the reaction time. The training methods have no significant effect on strike strength. Level of evidence II; Therapeutic studies - investigation of treatment results.

Assessment of sleep disturbances with the athlete sleep screening Questionnaire in Chinese athletes

This study investigated the factors that are associated with sleep disturbances among Chinese athletes. Sleep quality and associated factors were assessed by the Athlete Sleep Screening Questionnaire (ASSQ, n ​= ​394, aged 18–32 years, 47.6% female). Sleep difficulty score (SDS) and level of sleep problem (none, mild, moderate, or severe) were used to classify participants' sleep quality. Categorical variables were analyzed by Chi-square or fisher's exact tests. An ordinal logistic regression analysis was used to explore factors with poor sleep (SDS ≥8).

Approximately 14.2% of participants had moderate to severe sleep problem (SDS ≥8). Fifty-nine percent of the athletes reported sleep disturbance during travel, while 43.3% experienced daytime dysfunction when travelling for competition. No significant difference was found in the SDS category between gender, sports level and events. Athletes with evening chronotype were more likely to report worse sleep than athletes with morning and intermediate chronotype (OR, 2.25; 95%CI, 1.44–3.52; p ​< ​0.001). For each additional year of age, there was an increase of odds ratio for poor sleep quality (OR, 1.15; 95%CI, 1.04–1.26; p ​= ​0.004), while each additional year of training reduced the odds ratio (OR, 0.95; 95%CI, 0.91–0.99; p ​= ​0.044). To improve sleep health in athletes, chronotype, travel-related issues, age and years of training should be taken into consideration.

•

Sleep problems in athletes have been noticed in recent years. By using the clinically validated questionnaire (ASSQ) in Chinese athletes, we found that 14.2% of Chinese athletes had sleep disturbance.

•

By using a multivariate ordinal logistic regression model, we were able to detect chronotype, travel-related issues, age and years of training were important influencing factors on poor sleep quality in Chinese athletes.

•

The novel findings observed in this study shed new light on the current sleep health and possible factors affecting sleep disturbances of Chinese athletes and provide a new perspective for Chinese athletes to optimize their sleep strategies that improve sleep quality.

Sleep Architecture in Response to a Late Evening Competition in Team-Sport Athletes

Purpose: The aim of this study was to assess the effect of a late evening competition on sleep characteristics and perceived recovery in team-sport players using a validated self-applicable and portable polysomnographic device. Methods: Sixteen team-sport players (age: 25.4 [1.4] y; body mass index: 23.6 [0.5] kg/m2) completed the study. Objective and subjective sleep data were collected for 4 consecutive nights: 2 nights before (PRE2 and PRE1) and the 2 nights after an evening match (POST1), performed between 6:00 PM and 9:00 PM. Total quality of recovery values were also collected in the morning. Results: A significantly delayed bedtime (P < .0001; , large) was observed in the first night after the competition (2 h 29 min [1 h 15 min]) compared both to PRE2 (+88 min; P < .0001), PRE1 (+98 min; P < .0001), and POST1 (+100 min; P < .0001), and similar results were observed for wake-up time (P = .033; , large): Players woke up significantly later in evening match (9 h 20 min [1 h 55 min]) compared with PRE2 (+85 min; P = .050) and POST1 (+85 min; P = .049). Conversely, total sleep time; sleep efficiency; sleep onset latency; wake after sleep onset; cortical arousals; N1, N2, N3, and REM (rapid eye movement) percentages; total quality of recovery values; and scores of subjective sleep quality did not vary among the 4 study nights. Conclusions: Team-sport players had delayed bedtime and wake-up time following an evening competition; however, sleep quality, duration, and subjective scores of recovery were not affected by the evening match. The delayed wake-up time seems to protect athletes’ sleep efficiency/duration against the evening-match-induced delayed bedtime.

Different Intensities of Evening Exercise on Sleep in Healthy Adults: A Systematic Review and Network Meta-Analysis

The effects of different intensities of evening exercise on subsequent sleep remain contradictory. Thus, this systematic review and network meta-analysis aimed to compare and rank the effects of different intensities of acute evening exercise on sleep in healthy adults with good sleep. Articles were systematically searched journals indexed in the PubMed, Web of Science, Cochrane Library, Embase, and Scopus databases from inception to the 5th of May, 2022. The basic search terms included exercise, sleep and timing, which were combined with AND. Of the 12,203 retrieved, twenty-eight studies with 325 participants met the inclusion criteria. Results revealed that there were no significant differences in terms of impacts on sleep caused by different intensities of acute evening exercise, except that when compared to no exercise, acute evening high-intensity exercise decreased rapid eye movement sleep (mean difference [MD] = -1.95%, 95% credible interval [CI] = -3.58 to -0.35). Compared to no exercise, acute evening moderate-intensity exercise was ranked as the most potential method to improve sleep, displaying a trend to improve wake time after sleep onset (MD = -2.50 min, 95% CI = -8.17 to 1.62), sleep efficiency (MD = +0.41%, 95% CI = -0.71 to 1.66), the proportion of stage N1 (MD = -0.72%, 95% CI = -2.08 to 0.71) and N3 sleep (slow-wave sleep) (MD = +0.84%, 95% CI = -1.17 to 2.78). Acute evening low-intensity exercise displayed the greatest tendency to shorten sleep onset latency (MD = -1.02 min, 95% CI = -4.39 to 2.50) compared to no exercise. Overall, regardless of intensity, acute evening exercise completed before bedtime does not disrupt subsequent sleep in healthy young and middle-aged adults.

The effects of evening high-intensity exercise on sleep in healthy adults: A systematic review and meta-analysis

Moderate-intensity exercise is generally recommended for improving sleep, whereas, high-intensity exercise (HIE) prior to bedtime is often discouraged. We conducted a systematic review and meta-analysis to determine if acute or regular (chronic) HIE performed before bedtime disrupts nighttime sleep of healthy adult, good sleepers compared with a no-exercise control. Six databases (PubMed, EMBASE, Scopus, Web of Science, CENTRAL, and PsycINFO) were searched from inception to 31st May, 2021. Studies were experimental trials published in English language, objectively (polysomnography, actigraphy) and/or subjectively assessed sleep after evening HIE in sedentary and physically fit, good sleepers (aged 18-50 y old). The revised Cochrane risk of bias tool for randomized trials was used to assess risk of bias in the included studies. The random-effects model was used for the meta-analyses. We included 15 acute evening HIE studies in the meta-analysis with a total of 194 participants. Acute evening HIE ending 0.5-4 h before bedtime decreased rapid eye movement sleep (-2.34%; p = 0.002) compared with a no-exercise control. No other significant sleep changes occurred. A regular evening HIE did not disrupt nighttime sleep. Overall, acute evening HIE performed 2-4 h before bedtime does not disrupt nighttime sleep of healthy, young and middle-aged adults. PROSPERO, protocol registration number: CRD42020218299.

Sleep-Wake Behavior in Elite Athletes: A Mixed-Method Approach

Purpose

Using a mixed-method approach, this investigation aimed to examine athletes’ sleeping patterns along with the socio-physiological acute and chronic stressors affecting their sleep.

Methods

Fifteen elite athletes (M_age = 21.7 years; SD = 2.2) were monitored daily during a typical in-season training period (20 ± 1 days) and completed individual semi-structured interviews. Their sleep was analyzed using actigraphy and sleep diaries. A content analysis method was used to assess qualitative interviews.

Results

Three factors influencing sleep emerged from the qualitative interview analyses, i.e., sleep environment, training and study requirements. Half the athletes (8/15) complained about their sleeping environment with noise and/or bedroom temperature and/or mattress quality and/or light exposure presented as an issue. “Complainers” notably exhibited impaired (p < 0.05) sleep efficiency and wake after sleep onset compared with “non-complainers.” Daily training load showed correlations (p < 0.05) with wake after sleep onset and sleep onset latency. “Student athletes” exhibited later bedtime and earlier wake-up time compared with “non-student athletes,” leading to a reduced total sleep time (6:50 ± 1:13 vs. 7:06 ± 0:53; p < 0.05; d = 0.20).

Conclusion

An individualized assessment of sleep using actigraphy and interviews, with consideration to various socio-physiological factors, is recommended. Individualized sleep interventions with consideration to physiological (e.g., training load), behavioral (e.g., screen use) and environmental factors (e.g., room temperature, noise, mattress), can then be provided to each athlete.

Deconstructing athletes' sleep: A systematic review of the influence of age, sex, athletic expertise, sport type, and season on sleep characteristics

PURPOSE

This systematic review aimed to describe objective sleep parameters for athletes under different conditions and address potential sleep issues in this specific population.

METHODS

PubMed and Scopus were searched from inception to April 2019. Included studies measured sleep only via objective evaluation tools such as polysomnography or actigraphy. The modified version of the Newcastle-Ottawa Scale was used for the quality assessment of the studies.

RESULTS

Eighty-one studies were included, of which 56 were classified as medium quality, 5 studies as low quality, and 20 studies as high quality. A total of 1830 athletes were monitored over 18,958 nights. Average values for sleep-related parameters were calculated for all athletes according to sex, age, athletic expertise level, training season, and type of sport. Athletes slept on average 7.2 ± 1.1 h/night (mean ± SD), with 86.3% ± 6.8% sleep efficiency (SE). In all datasets, the athletes' mean total sleep time was <8 h. SE was low for young athletes (80.3% ± 8.8%). Reduced SE was attributed to high wake after sleep onset rather than sleep onset latency. During heavy training periods, sleep duration and SE were on average 36 min and 0.8% less compared to pre-season and 42 min and 3.0% less compared to in-season training periods, respectively.

CONCLUSION

Athletes' sleep duration was found to be short with low SE, in comparison to the general consensus for non-athlete healthy adults. Notable sleep issues were revealed in young athletes. Sleep quality and architecture tend to change across different training periods.

Nursing Intervention Based on Smart Medical Care on the Sleep Quality of Cardiology Patients

With the rapid development of society and the gradual improvement of people's living standards, patients with cardiovascular diseases have higher standards and requirements for daily health care and quality of life. The main research of this article is based on the observation of the effect of smart medical nursing intervention on the sleep quality of cardiology patients. The convenience sampling method was used to randomly select 80 cardiology patients from the electronic medical record system of the hospital, and the patients were randomly divided into two groups. One group was the control group. The routine nursing method was adopted, and a dedicated nurse paid attention to the sleep status; the other group was the control group. The research group adopts targeted nursing methods. This paper selects three kinds of sensor data as features. When collecting each scene record, it is first divided into sleeping and awake states, and then the classified time is composed of time segments, and these time segments are finally accumulated into sleep duration. Using sleep time, waking time, and sleep duration as input, the participants were divided into good sleepers and poor sleepers. Through a self-made questionnaire survey, the factors that have an adverse effect on the patient's sleep are divided into 7 aspects. Using the method of internal continuity measurement, Cronbach's coefficient a is 0.811, suggesting that the internal consistency is better, and the calculation reliability and validity are 86.1% and 83.4%, respectively, suggesting that the table can be used for sleep in hospitalized patients. The P values of the study group and the control group were 0.420, 0.764, 0.740, 0.881, 0.842, 0.119, and 0.342 (P > 0.05). The results show that the application of smart medical services has a certain effect on the patient's sleep quality.

Monitoring Individual Sleep and Nocturnal Heart Rate Variability Indices: The Impact of Training and Match Schedule and Load in High-Level Female Soccer Players

PURPOSE

To describe individual sleep habits and nocturnal heart rate variability (HRV) responses, and to explore intra-individual associations of workload with sleep and nocturnal HRV indices in high-level female soccer players throughout a 2-week competitive period.

MATERIALS AND METHODS

The study followed a descriptive, observational design. Thirty-four high-level female soccer players (aged 20.6 ± 2.3 years) wore wrist actigraph units and heart rate (HR) monitors during night-sleep to record objective sleep and HRV data throughout 14 days [six evening-time training sessions (ET), six rest-days (RD), and two match-days (MD)]. During each ET and MD, exercise HR (HRexe), %HRpeak, training impulse (TRIMP), session rating of perceived exertion (s-RPE) and perceived ratings of wellbeing were monitored.

RESULTS

After ET, a higher number of players (17-22) slept less than 7 h/night, in contrast to the remaining days (i.e., MD and RD), but only 1-6 players had a sleep efficiency < 75%. The coefficient of variation (CV) for sleep duration and sleep efficiency ranged between 9-22% and 2-11%, respectively. A small negative within-subject correlation was found between TRIMP and sleep duration [r = -0.25 (-0.36; -0.12); P < 0.001] and sleep efficiency [r = -0.20 (-0.32; -0.08); P = 0.004]. A moderate and small negative within-subject correlation was found between s-RPE and sleep duration [r = -0.43 (-0.53; -0.32); P < 0.001] and sleep efficiency [r = -0.17 (-0.30; -0.05); P = 0.02]. Nocturnal HRV for the time-domain analyses ranged from 4.1 (3.9; 4.3) to 4.4 (4.1; 4.6) ln[ms], and for the frequency-domain analyses ranged from 6.3 (5.9; 6.7) to 7.5 (7.1; 7.9) ln[ms2]. CV for time-domain HRV ranged from 3 to 23%, and from 4 to 46% for the frequency-domain. Higher CV fluctuations in time- and frequency-domain HRV were particularly observed in four players.

CONCLUSION

Overall, this study highlights the individual variability of sleep and nocturnal HRV indices, indicating that sleep duration may be affected by training and match schedules and workloads. Training and matches workload were not associated with nocturnal HRV in high-level female soccer players.

Listening to motivational music during warming-up attenuates the negative effects of partial sleep deprivation on cognitive and short-term maximal performance: Effect of time of day

This study assessed the effect of time of day (TOD) and listening to music during warm-up on cognitive and physical performances after partial sleep deprivation (PSD) and normal sleep nights (NSN). In a randomized order, twelve male physical education students [mean (SD) age 20.3 ± 2.0 y; BMI 22.90 ± 3.57 kg/m²)] completed a 30-s Wingate test (i.e., mean (MP) and peak powers (PP)), simple (SRT) and choice reaction times (CRT), a mental rotation test (MRT) and a selective attention test. Measurements were performed at 07:00 h and 17:00 h after a NSN and PSD with and without music, with an in-between recovery period of ≥72. Salivary cortisol was measured before and immediately after the Wingate test. Compared to NSN, the results showed that PSD decreased PP (p < .05, d = 0.86) and MP (p < .01, d = 0.86) in the afternoon. However, compared to NSN, listening to music during the warm up after PSD enhanced PP (p < .01, d = 1.40) and MP (p < .05, d = 0.82) in the morning and PP (p < .05, d = 0.78) in the afternoon. Moreover, listening to music lowered post-exercise cortisol in the morning both after NSN (p < .05, d = 0.79) and PSD (p < .05, d = 0.11). After PSD, music reduced the negative mood states (p < .01, d = 0.94), the SRT (p < .05, d = 0.79) and the CRT (p < .05, d = 0.49) in the afternoon. These findings suggest that listening to music during warm-up (i) enhances cognitive and short-term all out performances after NSN and PSD and (ii) partially counteracts sleep-loss-induced degradation of physical and cognitive performances at both TODs.

The Sleep and Recovery Practices of Athletes

BACKGROUND

Athletes maintain a balance between stress and recovery and adopt recovery modalities that manage fatigue and enhance recovery and performance. Optimal TST is subject to individual variance. However, 7-9 h sleep is recommended for adults, while elite athletes may require more quality sleep than non-athletes.

METHODS

A total of 338 (elite n = 115, 74 males and 41 females, aged 23.44 ± 4.91 years; and sub-elite n = 223, 129 males and 94 females aged 25.71 ± 6.27) athletes were recruited from a variety of team and individual sports to complete a battery of previously validated and reliable widely used questionnaires assessing sleep, recovery and nutritional practices.

RESULTS

Poor sleep was reported by both the elite and sub-elite athlete groups (i.e., global PSQI score ≥5-elite 64% [n = 74]; sub-elite 65% [n = 146]) and there was a significant difference in sport-specific recovery practices (3.22 ± 0.90 vs. 2.91 ± 0.90; p < 0.001). Relatively high levels of fatigue (2.52 ± 1.32), stress (1.7 ± 1.31) and pain (50%, n = 169) were reported in both groups. A range of supplements were used regularly by athletes in both groups; indeed, whey (elite n = 22 and sub-elite n = 48) was the most commonly used recovery supplement in both groups. Higher alcohol consumption was observed in the sub-elite athletes (12%, n = 26) and they tended to consume more units of alcohol per drinking bout.

CONCLUSION

There is a need for athletes to receive individualised support and education regarding their sleep and recovery practices.

Does the chronotype distribution vary between different level football leagues? Insights gained from Czech elite football players

Chronotype refer to individuals' time-of-day preferences for activities, which can be classified as "morning types = (M-types)", "evening types = (E-types)", and "neither types (N-types)". The primary aim of this study was to compare the chronotype distribution of Czech First League (1L) and Czech National Football League (2L) male elite football players, which was divided into two secondary aims: (i) statistically identify and compare the number (presence) of particular chronotypes in 1L, and (ii) statistically identify and compare the number (presence) of particular chronotypes in 2L. The present cross-sectional study employed a self-reported standardized questionnaire, the Composite Scale of Morningness, to study the chronotype distribution among the male elite football players. The chronotype distribution of 139 (85 from 1L with mean age ± S.D. = 25.5 ± 3.7 years and 54 from 2L age = 24.4 ± 4.5 years) players was assessed. Overall, 61 (71.8%) of the participants from 1L were mainly N-types, followed by M- and E-types. Similarly, 40 (74.1%) participants from 2L were mainly N-types, followed by M- and E-types. The statistical analysis of the 1L players showed a significantly higher presence of N-types compared to M- and E-types (χ²₍₂₎ = 57.62, p < .05, V = .58). The same results were detected in 2L, where the N-type was identified in the majority of football players (χ²₍₂₎ = 57.62, p < .05, V = .58). The statistical comparison of the number of presented chronotypes did not show a significant difference (F = 3.29, p > .05, V = .16) between players of the 1L and 2L. Thus, N-types are dominant among Czech elite football players, and the chronotype distribution of male elite football players from the Czech First League and the Czech National Football League does not vary.

High-Intensity Interval Exercise Performance and Short-Term Metabolic Responses to Overnight-Fasted Acute-Partial Sleep Deprivation

People practicing high-intensity interval exercise (HIIE) fasted during the morning hours under a lack of sleep. Such a habit may jeopardize the health benefits related to HIIE and adequate sleep. Fifteen habitually good sleeper males (age 31.1 ± 5.3 SD year) completed on a treadmill two isocaloric (500 kcal) HIIE sessions (3:2 min work:rest) averaged at 70% VO2reserve after 9-9.5 h of reference sleep exercise (RSE) and after 3-3.5 h of acute-partial sleep deprivation exercise (SSE). Diet and sleep patterns were controlled both 1 week prior and 2 days leading up to RSE and SSE. HIIE related performance and substrate utilization data were obtained from the continuous analysis of respiratory gases. Data were analyzed using repeated measures ANOVA with the baseline maximum oxygen uptake (VO2max) and body fat percentage (BF%) as covariates at p < 0.05. No difference was observed in VO2max, time to complete the HIIE, VE, RER, CHO%, and FAT% utilization during the experimental conditions. Whether attaining an adequate amount of sleep or not, the fasted HIIE performance and metabolism were not affected. We propose to practice the fasted HIIE under adequate sleep to receive the pleiotropic beneficial effects of sleep to the human body.

Influence of Perceptions of Sleep on Well-Being in Youth Athletes

ABSTRACT

Sawczuk, T, Jones, B, Scantlebury, S, and Till, K. Influence of perceptions of sleep on well-being in youth athletes. J Strength Cond Res 35(4): 1066-1073, 2021-To date, most research considering well-being questionnaires has only considered the training stress imposed on the athlete, without evaluating the questionnaire's relationship with a measure of recovery (e.g., sleep). This study aimed to assess the influence of sleep duration (Sduration), sleep quality (Squality), and sleep index (Sindex; Sduration × Squality) on well-being in youth athletes, while accounting for the known training stressors of training load and exposure to match play. Forty-eight youth athletes (age 17.3 ± 0.5 years) completed a daily questionnaire including well-being (DWBno-sleep; fatigue, muscle soreness, stress, and mood) measures, Perceived Recovery Status Scale (PRS), the previous day's training loads, Sduration, and Squality every day for 13 weeks. Linear mixed models assessed the impact of Sduration, Squality, and Sindex on DWBno-sleep, its individual subscales, and PRS. Sduration had a small effect on DWBno-sleep (d = 0.31; ±0.09), fatigue (d = 0.42; ±0.11), and PRS (d = 0.25; ±0.09). Squality had a small effect on DWBno-sleep (d = 0.47; ±0.08), fatigue (d = 0.53; ±0.11), stress (d = 0.35; ±0.07), mood (d = 0.41; ±0.09), and PRS (d = 0.37; ±0.08). Sindex had a small effect on DWBno-sleep (d = 0.44; ±0.08), fatigue (d = 0.55; ±0.11), stress (d = 0.29; ±0.07), mood (d = 0.37; ±0.09), and PRS (d = 0.36; ±0.09). The results indicate that an athlete's perceptions of sleep are associated with deviations in well-being measures and should be used as an input to the monitoring process rather than as part of the outcome well-being score. The sleep index is suggested as a potential input because it provides information on both the duration and quality of the sleep experienced.

Biological Rhythm and Chronotype: New Perspectives in Health

The circadian rhythm plays a fundamental role in regulating biological functions, including sleep–wake preference, body temperature, hormonal secretion, food intake, and cognitive and physical performance. Alterations in circadian rhythm can lead to chronic disease and impaired sleep. The circadian rhythmicity in human beings is represented by a complex phenotype. Indeed, over a 24-h period, a person’s preferred time to be more active or to sleep can be expressed in the concept of morningness–eveningness. Three chronotypes are distinguished: Morning, Neither, and Evening-types. Interindividual differences in chronotypes need to be considered to reduce the negative effects of circadian disruptions on health. In the present review, we examine the bi-directional influences of the rest–activity circadian rhythm and sleep–wake cycle in chronic pathologies and disorders. We analyze the concept and the main characteristics of the three chronotypes.

Influence of Training Schedules on Objective Measures of Sleep in Adolescent Academy Football Players

Brown, GA, Veith, S, Sampson, JA, Whalan, M, and Fullagar, HHK. Influence of training schedules on objective measures of sleep in adolescent academy football players. J Strength Cond Res 34(9): 2515-2521, 2020-Football academy settings may pose risks to adolescent athletes achieving sufficient sleep because of the contextual challenges these players face (e.g., psychosocial pressure, changes in training, competition, and academic stress). Given the importance of sleep to overall health as well as physical athletic development and injury risk, this study aimed to investigate whether differences in training schedules (morning vs. evening training sessions) affected objective measures of sleep in adolescent academy football (soccer) players. Twelve academy players (mean age 14.18 ± 1.36 years) wore an ActiGraph accelerometer on nights before, and nights of, training days in 2 separate weeks where morning (09:00-11:00 hours) and evening (18:00-20:00 hours) training occurred. Objective sleep parameters and training load data were collected. Night-time sleep periods were categorized as sleep preceding morning training, preceding evening training, or after evening training. One-way univariate and multivariate analyses of variance for repeated measures were performed to determine the impact of the training schedule on sleep. Significance levels were set at p < 0.05. The total sleep time was below the recommended guidelines (<8 hours) across conditions. A large significant effect of the training schedule on time attempted to fall asleep (p = 0.004, effect size [ES] = 0.40) and time of sleep (p = 0.003, ES = 0.41) was present, with post-evening sessions resulting in the latest times. Overall, the players' sleep behavior was resilient to changes in training schedules. However, the low sleep durations (and potential risks to physical performance/injury) suggest that sleep education coupled with practical interventions are required in this cohort.

To Nap or Not to Nap? A Systematic Review Evaluating Napping Behavior in Athletes and the Impact on Various Measures of Athletic Performance

PURPOSE

The objective of this systematic review was to 1) determine how studies evaluated napping behavior in athletes (frequency, duration, timing and measurement); 2) explore how napping impacted physical performance, cognitive performance, perceptual measures (eg, fatigue, muscle soreness, sleepiness and alertness), psychological state and night-time sleep in athletes.

METHODS

Five bibliographic databases were searched from database inception to 11 August 2020. Observational and experimental studies comprising able-bodied athletes (mean age ≥12 years), published in English, in peer-reviewed journal papers were included. The Downs and Black Quality Assessment Checklist was used for quality appraisal.

RESULTS

Thirty-seven studies were identified of moderate quality. Most studies did not include consistent information regarding nap frequency, duration, and timing. Napping may be beneficial for a range of outcomes that benefit athletes (eg, physical and cognitive performance, perceptual measures, psychological state and night-time sleep). In addition, napping presents athletes with the opportunity to supplement their night-time sleep without compromising sleep quality.

CONCLUSION

Athletes may consider napping between 20 to 90 min in duration and between 13:00 and 16:00 hours. Finally, athletes should allow 30 min to reduce sleep inertia prior to training or competition to obtain better performance outcomes. Future studies should include comprehensive recordings of nap duration and quality, and consider using sleep over a 24 hour period (daytime naps and night-time sleep period), specifically using objective methods of sleep assessment (eg, polysomnography/actigraphy).

Binge Eating Disorder: What Is the Role of Physical Activity Associated with Dietary and Psychological Treatment?

Binge eating patients present lower physical activity levels, which could be associated with lower exercise capacity. Specific physical activity can ensure broad beneficial results relating to eating disorders, depression, and body mass index (BMI) in bulimia; however, research on binge eating disorder (BED) is scarce. Our study aimed to investigate the effects of specific training as an addition to conventional treatment of eating disorder symptoms, anthropometric characteristics, and physical performance. Nineteen women with BED were included in a dietary and cognitive-behavioral therapy program. After medical examination, 10 women carried out Combined Aerobic and Anaerobic Exercise Training in addition to conventional treatment (CAAET group), whereas the remaining 9 followed the conventional treatment alone (CTRL group). All of the measurements were assessed before and after six months of treatment. In both groups, we observed a significant decrease in binge episodes, weight, and body mass index, and an increase in exercise capacity. Moreover, the CAAET group presented a greater improvement in aerobic performance than that observed in the CTRL group. Our results suggest that both interventions similarly improved BED symptoms. The addition of physical activity could be important in the long-term maintenance of both weight loss and reduction in binge episodes in BED patients.

Effect of High-Intensity Interval Training Versus Small-Sided Games Training on Sleep and Salivary Cortisol Level

PURPOSE

The authors compared sleep quality and salivary cortisol concentration after high-intensity interval training (HIIT) and small-sided games (SSGs) performed at the habitual training time in nonprofessional male soccer players.

METHODS

A total of 32 players (age = 24 [6] y, height = 1.77 [0.06] m, and body mass = 75 [12] kg) were randomized into an HIIT group or an SSG group. Actual sleep time, sleep efficiency (SE), sleep latency, immobility time (IT), moving time (MT), and fragmentation index were monitored using actigraphy before (PRE) and 2 nights after (POST 1 and POST 2) the training session. Salivary cortisol levels were measured before (PRE) and after (POST) training. Cortisol awakening response was evaluated.

RESULTS

Significant intragroup differences in the HIIT group were noted for actual sleep time (P < .0001), SE (P < .0001), sleep latency (P = .047), IT (P < .0001), MT (P < .0001), and fragmentation index (P < .0001) between PRE and POST 1 and for SE (P = .035), IT (P = .004), MT (P = .006), and fragmentation index (P = .048) between PRE and POST 2. Intergroup differences for actual sleep time (P = .014), SE (P = .048), IT (P < .0001), and MT (P = .046) were observed between the HIIT and the SSGs group at POST 1 were detected. Significant intragroup variations were observed in PRE and POST salivary cortisol levels (P < .0001 for HIIT; P = .0003 for SSGs) and cortisol awakening response (P < .0001 for HIIT; P < .0001 for SSGs). Significant intergroup differences between the HIIT and the SSGs group were found at POST (P < .0001) and in cortisol awakening response (P = .017).

CONCLUSIONS

Changes in actigraphy-based sleep parameters and salivary cortisol levels were greater after an acute session of HIIT than SSGs in this sample of nonprofessional male soccer players.

The effect of evening cycling at different intensities on sleep in healthy young adults with intermediate chronobiological phenotype: A randomized, cross-over trial

This study investigated the effect of various cycling intensities on sleep-related parameters in healthy young adults with intermediate chronobiological phenotype. Ten recreationally trained male volunteers underwent an evening i) moderate-intensity continuous training (MICT; 45 min at 70% W_max), ii) high-intensity interval training (HIIT; 10 × 1 min at 90% W_max), iii) sprint interval training (SIT; 6 × 20 sec at 140% W_max) or iv) a non-exercise (CON) trial in randomized, counter-balanced and crossover order. At baseline, somatometric data, maximum oxygen uptake and chronotype were evaluated. Sleep-related indices and daily activity were recorded by a multi-sensor activity monitor. Total sleep time was longer after SIT compared to CON and MICT (p < 0.05). Sleep efficiency was higher in SIT than in CON (p < 0.05). Sleep onset latency did not differ among trials. Wake after sleep onset was decreased after SIT compared to CON (p= 0.049). No differences were found for bedtime among trials. Wake time was earlier in the MICT trial compared to CON (p = 0.026). Evening cycling exercise -independently of intensity- did not impair sleep of individuals with intermediate chronobiological phenotype. Furthermore, a single SIT session improved sleep quantity and continuation of individuals with this specific chronotype.

A critical review on sleep assessment methodologies in athletic populations: factors to be considered

A growing body of research focus on athletes' sleep in order to investigate the effects of sleep in sports performance and recovery or the prevalence of sleep disorders in athletes. At the same time, several sleep monitoring tools have been developed and used in athletic populations for fulfilling these purposes. This review aimed to provide critical assessment to the most used by athletes' methodological approaches and compared them with the gold standard approach. Advantages and disadvantages of the various sleep monitoring tools were critically discussed. Literature related to aspects of athletes' sleep was reviewed. From the shortlisted studies, several factors that seem to affect sleep in athletes were identified using objective methods such as polysomnography/electroencephalography and actigraphy. These factors were associated to sleep (eg such as sleep environment, familiarization procedures and napping) and daily habits (eg nutrition, fluid consumption, alcohol and caffeine intake, tobacco use). The selected studies that evaluated sleep objectively were screened according the reporting rates of these variables. The majority of the screened studies were found to underreport these variables. Practical issues were addressed and recommendations about reporting sleep-related factors were made in order to improve studies' quality assessment and allow for more robust comparisons between studies.

Relationships between sleep, exercise timing, and chronotype in young adults

To examine the relationships between exercise timing, chronotype, sleep, and mood, college students (N = 909, 19.6 ± 1.4 years, 38% female) completed questionnaires immediately after exercising. Evening exercisers had later bedtimes, poorer sleep quality, and lower sleep efficiency compared to morning exercisers. Evening chronotypes reported poorer sleep quality, greater daytime dysfunction, and less positive affect compared to morning/neither chronotypes. Chronotype moderated the relationship between exercise timing and bedtime; with each minute delay in exercise timing, bedtime was delayed by 6.1 minutes in morning-types and only 3.6 minutes in evening-types. University health initiatives should target evening exercisers to mitigate the consequences of prolonged insufficient sleep.

Effects of Evening Exercise on Sleep in Healthy Participants: A Systematic Review and Meta-Analysis

BACKGROUND

Current recommendations advise against exercising in the evening because of potential adverse effects on sleep.

OBJECTIVES

The aim of this systematic review was to investigate the extent to which evening exercise affects sleep and whether variables such as exercise intensity or duration modify the response.

METHODS

A systematic search was performed in PubMed, Cochrane, EMBASE, PsycINFO, and CINAHL databases. Studies evaluating sleep after a single session of evening physical exercise compared to a no-exercise control in healthy adults were included. All analyses are based on random effect models.

RESULTS

The search yielded 11,717 references, of which 23 were included. Compared to control, evening exercise significantly increased rapid eye movement latency (+ 7.7 min; p = 0.032) and slow-wave sleep (+ 1.3 percentage points [pp]; p = 0.041), while it decreased stage 1 sleep (- 0.9 pp; p = 0.001). Moderator analyses revealed that a higher temperature at bedtime was associated with lower sleep efficiency (SE) (b = - 11.6 pp; p = 0.020) and more wake after sleep onset (WASO; b = + 37.6 min; p = 0.0495). A higher level of physical stress (exercise intensity relative to baseline physical activity) was associated with lower SE (- 3.2 pp; p = 0.036) and more WASO (+ 21.9 min; p = 0.044). Compared to cycling, running was associated with less WASO (- 12.7 min; p = 0.037). All significant moderating effects disappeared after removal of one study.

CONCLUSION

Overall, the studies reviewed here do not support the hypothesis that evening exercise negatively affects sleep, in fact rather the opposite. However, sleep-onset latency, total sleep time, and SE might be impaired after vigorous exercise ending ≤ 1 h before bedtime.

Acute sleep hygiene strategy improves objective sleep latency following a late-evening soccer-specific training session: A randomized controlled trial

The aim of this study was to evaluate the effects of sleep hygiene (SH) education on sleep quality in soccer players after a late-evening small-sided-game (SSG) training session. Twenty-nine non-professional players were recruited and allocated to either an experimental group (EG, n = 17) that received SH education, or a control group (CG, n = 12). SSG consisted of 3 × 4 min in a 4vs4, with 3 min of recovery and was performed at 8.00 p.m. Sleep quality was monitored via actigraphy and sleep diary entries before (PRE) and two nights after (POST1, POST2) the SSG. Sleep latency (SL) differed between the two groups at POST1 (4.9 ± 5.4 vs. 15.5 ± 16.1 for EG and CG, respectively; p = 0.017, effect size [ES] = 2.0); SL values were lower at POST1 compared to PRE for the EG (-47%; p = 0.021, ES = 0.6). Subjective sleep quality was better in the EG than the CG at POST1 (8.6 ± 1.0 vs. 7.1 ± 2.0 for EG and CG, respectively; p = 0.016, ES = 0.9) with a significant improvement over PRE-values (+11.0%, p = 0.004, ES = 0.8). Although SL and subjective sleep quality did not decrease significantly from POST1 to POST2 values at POST2 no longer differed significantly form baseline and, hence, indicate that observed effects may be short-lasting. No other objective sleep indices were influenced by late-evening training or SH practices implemented by the EG. Soccer players may benefit from acute SH strategies to reduce the time to sleep onset after late-evening training sessions.

Effect of chronotype on academic achievement in a sample of Italian University students

Circadian rhythms play an important role in biological function; their expression differs across individuals; three chronotypes are distinguished: Morning- [MT], Evening- [ET], and Neither- [NT] type. MT achieve peak activation in the first part of the day and are generally more conscientious and achievement-oriented than ET, which reach their best during the second half of the day and express a higher intelligence. University class schedules can sometimes conflict with ET circadian preferences, compromising their academic performance compared with their MT classmates. Conversely, MT students, being more aligned with their daily schedule, might be more advantaged in their mental performance. The attitudes and performance of NT students are little considered. No studies to date have investigated academic achievement in relation to chronotype in an Italian student population. To fill this gap, this study examined the relationship between chronotype and academic performance in a population of Motor Science Faculty in Milan, differentiating achievement in theoretical and practical subjects by chronotype. The study population was 423 university students (290 males and 133 females) and categorized by chronotype according to Morningness-Eveningness Questionnaire (MEQ) scores. Student transcripts were reviewed to obtain exam grades on three practical and three theoretical subjects. The interaction between MEQ score or chronotypes and mean exam grade was evaluated using one-way ANOVA. The mean grades on the theoretical and practical exams were higher for the MT than for either the ET or the NT students. The NT students (24.8 ± 0.1) had lower mean grades for the theoretical subjects than either the MT (26.3 ± 0.4) or the ET (25.3 ± 0.2) students, while the ET (26.6 ± 0.2) performed worse than either the MT (27.8 ± 0.2) or the NT students (26.9 ± 0.1) on the practical exams. The same trend was observed for the total sample and when subdivided by sex. In the total sample, significant differences in theoretical and practical exam grades were noted between chronotypes: MT vs ET (p < .002, p < .0006) and MT vs NT (p < .04, p < .003). The differences between the males were significant for the theoretical (p < .006, MT vs NT, p < .002) and the practical subjects (MT vs ET p < .004, MT vs NT, p < .01), but no significant differences were noted between the females. Our findings indicate overall better academic achievement by the MT students, whereas the NT had lower exam grades for the theoretical subjects and the ET performed worse on the practical exams. We speculate that the higher intelligence expressed by the ET students might have helped them compensate the disadvantage on the theoretical but not on practical exams, in which the effect of misalignment between circadian preferences and university class schedule was more evident.

The effect of exercise training on the quality of sleep in national-level adolescent finswimmers

Background

The purpose of the present study was to investigate whether the quality of sleep, in 91 national-level adolescent finswimmers, is affected by swimming style, swimming distance, and gender.

Methods

Twenty-four hours before the opening of the National Championship, the participants recorded the training characteristics and answered the following two questionnaires: Pittsburgh Sleep Quality Index (PSQI) and Epworth Sleepiness Score. Athletes were allocated to groups by gender, swimming style (monofin vs. bifin) and swimming distance (≤ 200 m vs. > 200 m). The dependencies between qualitative variables were estimated by chi-square test or Cramer’s V test with modification by Fisher’s exact test with cell frequencies less than 5. Binary logistic regression was used in the multi-factor model.

Results

There was a difference in the variables of PSQI “usual getting up time” and “have pain during sleep” between the two swimming distance groups (≤ 200 m vs. > 200 m). By using a multi-factor model (χ² = 13.541, p = 0.035), the variables of PSQI “usual getting up time” and “have pain during sleep” remained independent predictors of the swimming distance (p = 0.019, OR 1.75, 95% CI 1.09–2.81).

Conclusion

The athletes swimming distances > 200 m experience more episodes of pain during sleep and get up earlier than athletes swimming shorter distances.

Does Night Training Load Affect Sleep Patterns and Nocturnal Cardiac Autonomic Activity in High-Level Female Soccer Players?

Purpose: To analyze whether exercise training conducted at night disturbs sleep and affects nocturnal cardiac autonomic control in high-level female athletes. Methods: A total of 18 high-level female soccer players (mean [SD] age 20.4 [2.1] y) wore actigraphs and heart-rate (HR) monitors during night sleep throughout night training days (n = 8) and resting days (n = 8), for 3 consecutive weeks. This was a longitudinal study that measured internal training load, sleep, nocturnal cardiac autonomic activity, and well-being ratings prior to training sessions. Results: Training load varied across training days (eg, training impulse range, mean [SD]; effect size, ES [95% confidence interval]: 72.9 [18.8] to 138.4 [29.6] a.u.; F_4,62 = 32.331; ηp2=.673 [.001-.16], large effect; P < .001). However, no differences in subjective well-being ratings were observed, although ES was large. Total sleep time (training days vs resting days: 07:17 [00:47] h vs 07:51 [00:42] h; ES = 0.742 [0.59-0.92], P = .005; moderate effect) and sleep-onset time (00:58 [00:19] h vs 00:44 [00:16] h; ES = 0.802 [0.68-0.94], P = .001; moderate effect) were negatively affected after night training. In addition, small effects were detected for wake-up time, time in bed, and sleep latency (P > .05). No differences were detected in HR variability during sleep (range of lnRMSSD: 4.3 [0.4] to 4.5 [0.4] ln[ms] vs 4.6 [0.3] to 4.5 [0.4] ln[ms]; F_3,52 = 2.148; P > .05; ηp2=.112 [.01-.25], medium effect), but HR during sleep was significantly higher after training days (range of HR: 56 [4] to 63 [7] beats/min vs 54 [4] to 57 [6] beats/min; F_2,32 = 15.956; P < .001; ηp2=.484 [.20-.63], large effect). Conclusion: Overall, the results indicate that exercise training conducted at night may disturb sleep and affect HR, whereas limited effects can be expected in HR variability assessed during sleep in high-level female soccer players.

Observing Ramadan and sleep-wake patterns in athletes: a systematic review, meta-analysis and meta-regression

Objective

To evaluate the effect of observing Ramadan on athletes’ sleep patterns.

Design

Systematic review and meta-analysis.

Data sources

The entire content of PubMed/MEDLINE and Web of Science.

Eligibility criteria for selecting studies

Single-group, prepost and cross-over design studies conducted in athletes aged ≥18 years, training at least twice a week and published in English before 12 July 2018 were included. Studies assessing sleep quantity, quality, daytime sleepiness and/or daily naps based on objective or subjective methods were deemed eligible.

Study appraisal

The methodological quality was assessed using ‘QualSyst’.

Results

Of 13 selected articles, 7 were of strong quality, 3 were moderate and 3 were weak. 11 studies evaluated total sleep time (TST); this decreased during Ramadan in 4 studies, increased in 1 and remained unchanged in 6. Pooled TST findings indicated a moderate effect size (− 0.97, SE=0.37, 95% CI −1.69 to −0.25, t=−2.64, p=0.01) with significant heterogeneity but no publication bias. Meta-regressions showed no effects of study year, age, sample size, type of sport or competition level, but there were effects of country (with France and Tunisia being the most affected countries and Turkey the least affected, Q=32.14, p<0.0001) and study design (Q=7.74, p=0.02). Four studies measured self-reported sleep quality and it decreased in three studies. One study of sleep architecture reported more frequent waking and more light sleep during Ramadan. Daily nap duration was increased in two studies, but daytime sleepiness remained unchanged in four studies.

Conclusion

When athletes continue to train at least two times/week while observing Ramadan, TST is decreased compared with athletes’ baseline levels.

Heart Rate Variability in Sport Performance: Do Time of Day and Chronotype Play A Role?

A reliable non-invasive method to assess autonomic nervous system activity involves the evaluation of the time course of heart rate variability (HRV). HRV may vary in accordance with the degree and duration of training, and the circadian fluctuation of this variable is crucial for human health since the heart adapts to the needs of different activity levels during sleep phases or in the daytime. In the present review, time-of-day and chronotype effect on HRV in response to acute sessions of physical activity are discussed. Results are sparse and controversial; however, it seems that evening-type subjects have a higher perturbation of the autonomic nervous system (ANS), with slowed vagal reactivation and higher heart rate values in response to morning exercise than morning types. Conversely, both chronotype categories showed similar ANS activity during evening physical tasks, suggesting that this time of day seems to perturb the HRV circadian rhythm to a lesser extent. The control for chronotype and time-of-day effect represents a key strategy for individual training schedules, and, in perspective, for primary injury prevention.

Effects of morning vs. evening combined strength and endurance training on physical performance, sleep and well-being

The aim of the present study was to examine how combined strength and endurance training in the morning and evening influences the adaptations in strength and endurance performance, perception of time management, psychological well-being and sleep. The combined training period lasted for 24 weeks and the participants were divided into the morning training (MG, n = 18), evening training (EG, n = 24) and control groups (CG, n = 10). Isometric leg press force (iLP), maximal oxygen consumption (VO₂max), sleep behavior, fatigue, time management, motivation, self-esteem and health-related quality of life (HRQoL) were assessed. Morning to evening difference in iLP was observed in both MG and EG at Pre and Post, with higher force values in the evening, but not for VO₂max. iLP force increased significantly in EG in the morning (p < 0.001) and evening (p = 0.010). VO₂max increased in MG and EG both in the morning (both p < 0.001) and in the evening (MG: p < 0.001; EG: p = 0.003). Participants of the present study slept 7-8 h per night and the self-reported sleep duration, get-up time and the average time to go to bed were similar between the groups and did not change from Pre to Post. From HRQoL dimensions, the score for bodily pain decreased in MG (p = 0.029) and significant between-group differences were observed for Pre-Post changes in MG and EG (p = 0.001) as well as between MG and CG (p < 0.001). In vitality, a significant between-group difference was observed for Pre to Post changes in MG and EG (p = 0.014). Perception of time management decreased in EG (p = 0.042) but stayed unchanged for MG and CG. For the intrinsic motivation to participate, significant between-group differences were observed for MG and EG (p = 0.033) and between MG and CG (p = 0.032) for Pre to Post changes. Self-esteem improved in MG (p = 0.029) and EG (p = 0.024). The present combined strength and endurance training program performed in the morning and in the evening led to similar improvements in strength and endurance performance. Training in the morning or in the evening did not disrupt the already good sleep behavior and it was able to further increase the self-esteem. Although training in the morning hours may leave more time for free time activities or social life (i.e. family and friends) compared to the evening training, it might be more challenging to stay motivated to participate in prolonged training programs in the morning hours.

48-Hour Effects of Monitored Cooperative High-Intensity Interval Training on Adolescent Cognitive Functioning

Physical activity has been positively related to better cognitive performance though the effects of varied exercise type and intensity and the duration of cognitive benefits are unclear. This study analyzed the effect of 16 minutes of monitored cooperative high-intensity interval training (monitored C-HIIT) at the start of the school day, on various cognitive variables over the next 24-48 hours. We randomly assigned 158 participants either to a control group ( n = 81) that engaged only in static stretching or to an experimental group ( n = 77) that performed monitored C-HIIT. We assessed cognitive functioning before the exercise, immediately afterward, and for five follow-up time points over the next two days (i.e., at 2, 3, 4, 24, and 48 hours). We analyzed age, sex, body mass index, and moderate-to-vigorous physical activity as potential confounder variables. Adolescents in the monitored C-HIIT group increased selective attention by 17.39% during the next hour ( p = .015) and increased concentration by 20.31% and 15.26% during the first ( p = .022) and second ( p = .059) subsequent hours, respectively. This positive short-term benefit of monitored C-HIIT during immediate subsequent hours is an important finding with implications for the school curricula and schedule.

Effect of a Night Game on Actigraphy-Based Sleep Quality and Perceived Recovery in Top-Level Volleyball Athletes

PURPOSE

To evaluate actigraphy-based sleep quality and perceived recovery before and after a night game in top-level volleyball athletes.

METHODS

Data on sleep parameters were collected by actigraphy for 3 consecutive nights with 24 elite athletes (12 male and 12 female; mean age [SD] = 26.0 [3.4] y, age range = 20-33 y) during the competitive season 2016-17. Data from 1 night before and 2 nights after an official night match were studied, and athletes' subjective perception of recovery was evaluated by the Total Quality Recovery scale. The following actigraphic parameters were studied: time in bed, sleep latency, sleep efficiency, wake after sleep onset, total sleep time, immobility time, moving time, and fragmentation index.

RESULTS

The analysis highlighted significant differences for all sleep variables. Total sleep time was lower the first night after the match compared with prematch sleep (P = .02) and the second night (P = .0009) after night competition (P = .0001, F_2,23 = 22.93, ηp2 = .66 ). Similarly, sleep efficiency was lower immediately after the night competition compared with both prematch values (P = .03) and the second night (P = .0003) after competition (P = .0005, F_2,23 = 8.93, ηp2 = .44 ). The same differences were observed in the perceived recovery values (P = .001, F_2,23 = 13.37, ηp2 = .54 ).

CONCLUSIONS

Coaches and medical staff should use these findings to develop a greater knowledge of how sleep differs during different phases of competition and to implement behavioral and sleep-hygiene strategies in top-level athletes.