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Sleep, circadian rhythms, and athletic performance
... In this regard, an increase in core body temperature has been associated with enhanced muscle compliance, augmented energy metabolism, and improved blood flow to exercising muscles, while facilitating actin-myosin cross-bridging, thus enhancing exercise performance (Starkie et al. 1999;Bishop 2003). Further, experimental evidence has shown that muscular strength peaks in the late afternoon and early evening, and similar peaks have also been reported for anaerobic exercise and short-term power output (Thun et al. 2015;Mirizio et al. 2020). In this sense, extended morning warm-up was suggested as an effective strategy to reduce diurnal performance variation (Kusumoto et al. 2021). ...
... Increases in body temperature in the afternoon have been suggested to facilitate the contractile mechanics in the muscle, which may result in improved physical performance (Starkie et al. 1999). A body of literature indicates that the peak of circadian body temperature in the afternoon is associated with high anaerobic power output and joint flexibility, increased muscle strength and cardiovascular efficiency, as well as an increased coordination and a shorter reaction time (Atkinson and Reilly 1996;Bishop 2003;Drust et al. 2005;Souissi et al. 2007;Chtourou et al. 2011;Zarrouk et al. 2012;Thun et al. 2015;Mirizio et al. 2020). ...
... Sleep is an integral part of the recovery and adaptive process between training sessions. Increased sleep duration and improved sleep quality in athletes are associated with enhanced performance (Thun et al. 2015;Watson 2017). Regarding endurance performance, some studies have demonstrated that sleep deprivation inhibits performance, perhaps through an increase in perceived exertion, neuromuscular fatigue, and decrease in glycogen stores (Temesi et al. 2013;Fullagar et al. 2015). ...
The aim of this study was to determine the influence of time of day (ToD) on jump enhancement in endurance runners with different training backgrounds and chronotypes. Twenty-one male runners were divided in novice (NOV, n = 9), and experienced (EXP, n = 12). Chronotypes, sleep quality and countermovement jump (CMJ) performances were assessed. CMJ height was measured before and after a 30-min submaximal (~70% HRR) running bout on a treadmill in the morning vs. evening. Post-running CMJ performance was recorded at 0, 3, 6 and 9 min of recovery. Most athletes (77.3%) were categorized as morning types. There was a significant interaction (p = 0.003) between ToD and CMJ performance timepoint for the whole sample. Moreover, CMJ height post warm-up was significantly higher in the evening vs. morning (33.47 ± 7.31 vs. 32.07 ± 6.87 cm, p = 0.037). However, post-running CMJ performance only improved at 0 and 3 min of recovery during morning bouts in EXP (p = 0.005), while NOV did not exhibit jump enhancement. We conclude that post warm-up jump performance is greater in the evening vs. morning. However, endurance runners with more training experience showed greater jump enhancement in the morning after a 30-min submaximal running bout.
... Increases in performance levels are accomplished with gradually increased training frequency, intensity and training load [16]. Previous studies in the field indicate that the key factors influencing athlete performance include innate skill level, physical fitness and health, physical properties [17], rest [18], [19], nutrition [20], [21], hydration [22], mental health and psycho-physiological states [23]- [25], and tactical strategies [26], [27]. Studies emphasize the need for holistic approaches to understand performance, considering not just physical training but also recovery, physiological signals, and mental well-being [19]. ...
... Our results align with existing literature regarding sleep's impact on sports performance [18], [69] and the relationship between Heart Rate Variability (HRV), VO 2max , and athletic performance [56], [70]. However, counter-intuitive patterns in real-world data collection may be influenced by external factors such as individual skill levels, player positions, and academic commitments [17], [71]. ...
Predicting performance outcomes has the potential to transform training approaches, inform coaching strategies, and deepen our understanding of the factors that contribute to athletic success. Traditional non-automated data analysis in sports are often difficult to scale. To address this gap, this study analyzes factors influencing athletic performance by leveraging passively collected sensor data from smartwatches and ecological momentary assessments (EMA). The study aims to differentiate between 14 collegiate volleyball players who go on to perform well or poorly, using data collected prior to the beginning of the season. This is achieved through an integrated feature set creation approach. The model, validated using leave-one-subject-out cross-validation, achieved promising predictive performance (F1 score = 0.75). Importantly, by utilizing data collected before the season starts, our approach offers an opportunity for players predicted to perform poorly to improve their projected outcomes through targeted interventions by virtue of daily model predictions. The findings from this study not only demonstrate the potential of machine learning in sports performance prediction but also shed light on key features along with subjective psycho-physiological states that are predictive of, or associated with, athletic success.
... A recent study from 2015 found the biggest factor in predicting performance was the time between when the body would naturally wake up and when the exercise was performed (Scott & Russell, 2015). Additionally, Thun et al., 2015 completed a systematic review and found one study in which "American football teams travelling eastwards to visit their opponents were found to perform worse than RUNNING HEAD: SLEEP REGULARITY AND ATHLETIC PERFORMANCE 4 teams travelling westwards (i.e., scored fewer points, had more points scored against them, and were beaten by higher margins)" (Thun et al., 2015). ...
... A recent study from 2015 found the biggest factor in predicting performance was the time between when the body would naturally wake up and when the exercise was performed (Scott & Russell, 2015). Additionally, Thun et al., 2015 completed a systematic review and found one study in which "American football teams travelling eastwards to visit their opponents were found to perform worse than RUNNING HEAD: SLEEP REGULARITY AND ATHLETIC PERFORMANCE 4 teams travelling westwards (i.e., scored fewer points, had more points scored against them, and were beaten by higher margins)" (Thun et al., 2015). ...
... Cognitive functioning fluctuates throughout the day [4,28]. Blake [4], for example, showed that players performed worse at a card sorting and digit span task at night than in the morning. ...
... The time of day affects people in different ways. It influences decision making [3], task performance [4], unethical behavior [18], or physical performance [28]. This is due to the body's circadian clock [24] and sleep pressure, which increases throughout the day [25]. ...
Cognitive functioning fluctuates throughout the day. Previous work found that the time of day influences player performance in video games. Game designers also frequently leverage day and night cycles in game worlds to create realistic player experiences. It is, however, unclear whether and how the time of day in the game world affects player performance. Hence, we conducted a study with 24 participants who completed a maze game in the late morning or evening, while being immersed in a game world with a corresponding in-game day and night time. We showed that participants had a better memory performance during in-game day time than in-game night time. We also found that participants had a faster overall task completion time during the late morning than evening. Results suggest that not only the real day time but also the virtual day time can influence players' performance. We discuss potential explanations such as lighting conditions and priming effects.
... A body of research has indicated that athletic performance can be impaired by MPD through causing the sleep disturbance and irregular lifestyle (Thun et al., 2015;Romyn et al., 2016;Charest and Grandner, 2020;Gupta, 2023). Sleep is often considered as the key to achieving the optimal athletic performance, and sleep deprivation leads to a variety of physical and psychological consequences, including stress, anxiety, and decreased coping and recovery. ...
... For athletes, due to long-term focus on training and competition, while facing greater pressure, such group are more inclined to regard mobile phones as "stress release device" and "psychological refuge". This implies that athletes are more susceptible to the detrimental effects of MPD, including distraction, mental fatigue, impaired decision-making, sleep disturbance, and poor social relationship, which can seriously hinder athletic performance (Stothart et al., 2015;Thun et al., 2015;Isoard-Gautheur et al., 2016;Romyn et al., 2016;Wachsmuth et al., 2018;Charest and Grandner, 2020;DesClouds and Durand-Bush, 2021;Fortes et al., 2021Fortes et al., , 2022aFortes et al., ,b, 2023Alix-Fages et al., 2023;Lima-Junior et al., 2024). Therefore, early detection and effective intervention of MPD problems in athletes have become necessary and significant for improving their training and competition performance. ...
Mobile phone dependence (also known as internet dependence, MPD), defined as a problematic behavior characterized by excessive use or intermittent craving to use a mobile phone, results in various social, behavioral, and affective problems in daily life. In sports, MPD is directly related to the physical and mental health and sports performance of athletes. The individual and environmental factors, neurobiological mechanisms and theoretical models of MPD affecting athletic performance were analyzed by reviewing previous studies, aiming to construct effective training and development protocols to prevent and control the occurrence of MPD in athletes. At present, athletic performance can be affected by MPD through individual factors and environmental factors. The neurobiological mechanisms between the two are based on the brain reward system and microwave radiation from mobile phones, with athletic performance being restricted by alterations in the corresponding brain regions. Relevant theoretical models mainly include the social cognitive model of self-regulation and the integrative model of self-control, which explain the interrelationship between MPD and athletic performance from the perspectives of athletes' self-regulation and self-control, respectively. As an emerging phenomenon, the influence pathways and mechanisms by which MPD affects athletic performance need to be further investigated. A longitudinal perspective should be adopted to trace the dynamic impact relationship between the two, and developing relevant theoretical frameworks from an interdisciplinary research perspective should be valuable for providing theoretical support for coaches and sports administrators to formulate scientific training protocols and thus improve the mental health of athletes.
... Laboratory research has shown that a number of sensory, perceptual, and motor functions can be altered by insomnia or lack of adequate sleep. The circadian rhythm of sleep has positive effects on improving the athletic performance and if this rhythm is disturbed for any reason, it has negative effects on the quality of athletes' performance (12). Insomnia has a great effect on cognitive impairment, accuracy and concentration and even the quality of training (13). ...
... Research has shown that partial sleep deprivation increases reaction time and decreases selective and continuous attention (1). Research has shown that performance on the Stroop test is highly associated with an increase in reaction time and the number of errors following sleep deprivation in females (12). Sleep deprivation affects the entire attention network, which is made up of many closely related connections to cortical areas. ...
Background: Melatonin is one of the Supplements used to treat sleep problems such as insomnia and jet lag. Objectives: Since sleep deprivation may affect athletic performance, the aim of this study was to investigate the effect of melatonin on neurological function and maintenance of physical and motor fitness in collegiate student-athletes following sleep deprivation. Methods: Ten collegiate student-athletes participated in randomized, double‐blind crossover trial with placebo control. Subjects were divided into six experimental groups: without sleep deprivation (WSD), 4 hours sleep deprivation (4HSD) and 24 hours sleep deprivation (24HSD) with melatonin (MEL) or placebo (PLA). WSD were allowed to sleep eight hours per night. Six milligrams of melatonin was administered 30 min before the training protocols. Training protocols included the Wingate Anaerobic test, Good Balance test, Vienna reaction time with the Stroop test. Data were analyzed using repeated measures ANOVA. Significant difference was set at P ≤ 0.05. Results: Six mg/day of MEL 30 min before training had no significant effect on anaerobic power, balance and reaction time in collegiate student-athletes WSD (P > 0.05). Although, 4HSD and 24HSD negatively affected balance function, MEL reduced its negative effects. Furthermore, 24HSD decrease neurological and physical performance in collegiate student-athletes and MEL improved anaerobic power and reaction time in collegiate student-athletes (P < 0.05). Conclusions: Pre-training MEL supplementation would alleviate neurological, physical and motor performance impairment in collegiate student-athletes following sleep deprivation. MEL appears to be more effective in athletes with longer sleep deprivation.
... Endurance training is more energetically costly. Aerobic athletes have a higher sleep need than their anaerobic athlete counterparts (Trinder et al., 1985), and anaerobic muscle power and strength are less affected by insufficient sleep (Thun et al., 2015). The impact of insufficient sleep on physiological systems required to perform optimally in endurance activities is significant. ...
... The impact of insufficient sleep on physiological systems required to perform optimally in endurance activities is significant. Insufficient sleep leads to early onset of anaerobic thresholds during endurance-based tests as well as reductions in insulin sensitivity and glucose availability (Thun et al., 2015). These considerations are integral for determining an ideal sleep/training schedule for endurance athletes across the competition season and support the need for analyzing competition schedules for each sport as well as the performance, academic, and health outcomes resulting from those schedules. ...
Collegiate athletes must satisfy the academic obligations common to all undergraduates, but they have the additional structural and social stressors of extensive practice time, competition schedules, and frequent travel away from their home campus. Clearly such stressors can have negative impacts on both their academic and athletic performances as well as on their health. These concerns are made more acute by recent proposals and decisions to reorganize major collegiate athletic conferences. These rearrangements will require more multi-day travel that interferes with the academic work and personal schedules of athletes. Of particular concern is additional east-west travel that results in circadian rhythm disruptions commonly called jet lag that contribute to the loss of amount as well as quality of sleep. Circadian misalignment and sleep deprivation and/or sleep disturbances have profound effects on physical and mental health and performance. We, as concerned scientists and physicians with relevant expertise, developed this white paper to raise awareness of these challenges to the wellbeing of our student-athletes and their co-travelers. We also offer practical steps to mitigate the negative consequences of collegiate travel schedules. We discuss the importance of bedtime protocols, the availability of early afternoon naps, and adherence to scheduled lighting exposure protocols before, during, and after travel, with support from wearables and apps. We call upon departments of athletics to engage with sleep and circadian experts to advise and help design tailored implementation of these mitigating practices that could contribute to the current and long-term health and wellbeing of their students and their staff members.
... Participants were instructed to maintain their regular diet and avoid high-intensity exercise, caffeine, and alcohol consumption within 24 hours prior to study sessions. All sessions were completed at the same time of day (within 2 ± 1 h) to minimise the influence of circadian rhythm on power output (Thun et al., 2015). The sRPE TL for team-sport training performed outside the study period has previously been reported (McKee, Girard, Peiffer, Hiscock, et al., 2024). ...
... In the present study, PSS scores were relatively low. A possible explanation for these low scores in the present study is that most participants (67.6%) were classified as 'good sleepers' and previous research has consistently highlighted the role of good quality sleep in the management and reduction of stress (Thun et al., 2015). ...
Subjective sleep and stress are strongly associated, at multiple levels, and the current body of evidence highlights a bi-directional association. Previous research has highlighted that issues with sleep can impact on several stress responses. On the other side of this relationship, research has shown that stress-inducing factors can significantly impact sleep. The present study examined this association in a sample of recreational athletes, a population that has received little to no research focus to date Recreational athletes are defined as individuals who exercise >4 hours per week for health, fitness, or unofficial competitions. Recreational athletes (n = 34) completed online measures of subjective sleep, subjective stress, subjective anxiety/depression and training load (PSQI, PSS, HADS and DALDA). Pearson correlations were carried out to examine associations between variables. There was a significant positive correlation between subjective sleep quality and subjective stress. There was a significant positive correlation between subjective stress and training load. There was a significant positive correlation between subjective sleep quality and training load. The positive associations between sleep, stress and training load are consistent with previous research, but the present study adds to the literature by highlighting the associations in recreational athletes. Recreational athletes should proactively manage their sleep and stress, as due to the bi-directional relationship, improving sleep may benefit stress, and improving stress may benefit sleep quality. This is also likely to benefit overall mood and reduce the likelihood of overtraining in recreational athletes.
... In our study, we focus on the fatigue response of shift workers concerning their sleep chronotype, referring to behavioral manifestations of the endogenous circadian system that directs the preferred timing of sleep and wakefulness (Costa, 1996;Kalmbach et al., 2017;Yang et al., 2021). Deviations or disturbances in the chronotype contribute to reduced recovery periods, primarily due to sleep deprivation, irregular sleep cycles, insomnia, and circadian rhythm disruption (Boivin & Boudreau, 2014;Thun et al., 2015). Our exploration extends to "social jetlag," the discord between an individual's natural chronotype and their imposed work schedule (Rutters et al., 2014). ...
The complex interplay between temporal factors and employee well-being is a pressing concern in the modern workplace, particularly among industrial shift-workers. Shift work has far-reaching consequences, affecting not only productivity but also psychosomatic health, quality of life, and overall wellness. This study aimed to investigate the impact of shift time pattern on psychosomatic health as well as the sleep quality of industrial workers by established subjective assessment tools with a comprehensive statistical analysis. We conducted a comprehensive study of 5432 Indian industrial workers (iron & steel industries), categorizing them into two groups: regular workers (Test Group-I, 52.1%) and rotational shift-workers (Test Group-II, 47.9%). Participants worked an average of 55.6 and 58.9 h/week, respectively. We assessed psychosomatic health using standardized instruments, including the Fatigue Assessment Scale, Physical Health Questionnaire, and Sleep Disorder Questionnaire. The analysis revealed a significant increase in fatigue symptoms, with 46.3% of TG-I and 46.8% of TG-II workers at elevated risk (p < 0.01). Similarly, 54.6% of TG-I and 59.9% of TG-II workers exhibited high-risk somatic symptom severity (p < 0.001), and 29.1% of TG-I and 48.5% of TG-II workers were at elevated risk of sleep disorders (p < 0.001). These findings starkly contrast with those of the general population. The study highlights the profound physiological and psychological toll of shift work on industrial workers, who often struggle to align their circadian rhythms, manage somatic symptoms, and sleep disorders, leading to elevated fatigue levels. These challenges contribute to mood disturbances, stress, and social isolation, underscoring the urgent need for targeted interventions to mitigate the adverse effects of shift work.
... Kazanılan ikinci servis puanlarının yüzdesi, erkek oyuncular için maç galibiyetleri ve mağlubiyetleri arasında farklılık gösterirken, kadın oyuncular için kazananlar ve zorunlu hatalar farklıdır (Turner, Beranek, Dunican, & Cruickshank, 2023). Uyku, sirkadiyen ritimler ve atletik performans üzerine yapılan incelemede, uyku yoksunluğunun dayanıklılık performansı üzerinde olumsuz etkisi olduğunu ve akşam performansını sabah performansından daha fazla etkiliyor olduğunu göstermektedir (Thun, Bjorvatn, Flo, Harris, & Pallesen, 2015). Elit erkek bisikletçilerde antrenman yükünün uyku kalitesi ve uyku algısı üzerine etkisini araştıran çalışmada, toplam uyku süresi ve uyku verimliliği, başlangıca kıyasla yüksek antrenman aşamalarında önemli ölçüde azalmıştır ve ortalama aktivite puanı önemli ölçüde artmıştır. ...
... The influence of circadian rhythm on exercise performance has been demonstrated in numerous studies [2]. In general, the optimal time for exercise performance is usually in the evening due to the higher core body temperature, which leads to increased energy Nutrients 2024, 16, 3151 2 of 9 metabolism, improved muscle compliance, and the promotion of actin-myosin crossbridging [3]. ...
The purpose of this study was to examine the impact of caffeinated chewing gum on the physical performance of elite ice hockey players after a jet lag intervention. Fourteen national-level (age: 25.2 ± 5.4; height: 176.5 ± 5.3; weight: 78.1 ± 13.4) ice hockey players were tested late at night after a full day awake schedule with jet lag. A randomised, double-blind experimental design was employed in which participants either chewed caffeinated gum (CAF) containing 3 mg/kg caffeine or a caffeine-free placebo gum (PLA) for 10 min prior to undertaking a series of on-ice and off-ice tests. The off-ice tests included grip force, the counter-movement jump (CMJ), and the squat jump (SJ). The on-ice tests included a 35 m sprint, the S-Shape agility test, and the Yo-Yo intermittent recovery test (Yo-Yo IR1 test). The CMJ height (CAF: 47.2 ± 4.4; PL: 45.9 ± 3.5; p = 0.035; Cohen’s d = 0.32) and SJ height (CAF: 46.7 ± 4.1; PL: 44.9 ± 3.8; p = 0.047; Cohen’s d = 0.44) were found to be significantly higher in the CAF than in the PL trial. However, there were no significant differences (p > 0.05) in grip force, as well as in the 35 m sprint, the S-Shape agility test, and the Yo-Yo IR1 test. The present study found that, following a jet lag intervention, although the consumption of caffeinated gum resulted in an increase in vertical jump height, it had no impact on performance in the ice tests. The results of this study may help coaches and athletes consider the need for caffeine supplementation when experiencing jet lag.
... Athletes in pursuit of current and previous world records have continuously run for durations of up to 4 days and nights. This extended wakefulness can detrimentally impact both physical performance (Thun et al., 2015) and cognitive function (Bobić et al., 2016). ...
Ultrarunning is gaining in popularity but no information is available on the physiological and psychological responses during backyard ultrarunning events. The aim of this study was to determine changes in cognitive function, markers of physiological resilience, and running performance during a backyard‐running event. Twelve male ultrarunners (38 ± 8 years old, BMI: 23.5 ± 1.6 kg/m², and VO2max: 60.8 ± 4.7 mL/min/kg) were monitored before, during, and after the event. Cognitive performance was determined using a cognitive test battery before, during, and after the event. During the event, the rating of perceived exertion (RPE), blood lactate concentration, and heart rate (HR) were assessed. Physical performance was investigated using the total number of completed laps and running speed per lap. Athletes completed 34 ± 17 laps equaling 227.8 ± 113.9 km with average speeds starting at 9.0 km/h and slowing down to 7.5 km/h at the end of the event. Physiological resilience (estimated using HR/speed) varied between athletes, with significantly lower values in the more proficient backyard runners at the end of the event (p < 0.05). HR and lactate levels remained constant, whereas a progressive increase in RPE was noticed (p ≤ 0.001). A significantly worsened reaction time was observed for several cognitive tasks after the event compared to baseline measures (p ≤ 0.05). These observations show that physiological resilience differs depending on the level of endurance performance of the athletes. Furthermore, the backyard ultrarunning event negatively impacted psychomotor speed. Therefore, the results suggest that implementing strategies that enhance physiological resilience and/or psychomotor speed could potentially have a positive effect on performance in ultraendurance activities.
... For example, in an independent study involving total sleep deprivation, the researchers noted the absence of a temporal rhythm effect across the four measured time points (06:00, 10:00, 14:00, and 18:00) (Bougard et al., 2016). While some researchers have attributed improved nocturnal performance to the interaction between the sleep and circadian processes (Thun et al., 2015), we propose that individual differences may account for the observed variations in this rigorously controlled sleep study. ...
... In this study, cortisol hormone was significantly higher in the morning hours and also in FP in accordance with the literature. As stated before, body temperature is generally considered as the primary endogenous indicator of the CR [45], and studies indicate that body temperature increases in the LP due to the thermogenic effects of PRO [23]. In addition, the peak body temperature, which occurs in the first part of the evening, has been shown to lead to higher carbohydrate utilization and to facilitate the mechanics of the actin-myosin cross bridge in the muscle unit [46]; this in turn cause an increase in short term maximal performance. ...
This study assessed the repeated sprint performance in relation to circadian rhythm during different menstrual cycle phases(MCP). Twelve volunteer eumenorrheic women team sport athletes performed 5x6-s cycling sprints in morning (9 am-10 am) and evening (6 pm-7 pm) sessions during the mid-follicular (FP, 6–10th d) and luteal phases (LP, 19–24th d). Body weight, oral body temperature, resting heart rate and lactate levels together with estradiol, progesterone and cortisol levels were determined before tests. Relative peak and mean power and performance decrements were determined as performance variables and maximum heart rate, lactate and ratings of perceived exertion were determined as physiological variables. Evening body temperatures were significantly higher. Cortisol levels were higher in the morning and in the FP. Resting lactate levels did not vary with MCP or time of day, but a significant MCP x time of day interaction was observed. Body weight showed no change according to time of day and MCP. There was no significant effect of MCP and time of day on performance and physiological variables, in contrast, maximum lactate values were notably higher in the evening. In conclusion, MCP and time of day need not be considered during repeated sprint exercises of eumenorrheic women athletes.
... De même, des mouvements plus complexes, notamment issus du domaine sportif, présentent également cette rythmicité circadienne, avec des variations de la longueur du saut (Reilly and Down, 1992), de la précision des services au badminton et de la vitesse de nage (Kline et al., 2007). La majorité de ces études montrent des performances optimales en fin de journée (16 à 18 heures), que ce soit sur les tâches motrices simples ou complexes (Atkinson and Reilly, 1996;Drust et al., 2005;Thun et al., 2015). Les performances motrices peuvent également fluctuer en fonction du chronotype, montrant par exemple des pics de performance plus précoces pour les individus du matin que pour ceux du soir (Vitale and Weydahl, 2017). ...
While the time of day significantly affects motor and mental performance, its influence on motor learning has not yet been elucidated. In this thesis, we conducted a series of experiments using a finger-tapping task to investigate the effects of time of day on two processes of motor learning: acquisition (i.e. skill improvement immediately after a training-session) and consolidation (i.e. skill retention after the passage of time and/or a night of sleep).
In the 1rt study, we showed that the time of day influenced the consolidation, but not the acquisition. Specifically, while we observed deterioration and stabilization of skill 24 hours after morning and afternoon training, respectively, we found a better consolidation 24 hours after evening training with a subsequent improvement in skill. These results highlight the crucial role of sleep in consolidating motor skills acquired beforehand.
In the 2nd study, comprising four experiments, we explored the question of the fragility of memory after morning training. Our initial results showed that memory was more fragile in the morning than in the afternoon, with deterioration occurring within 5 hours of practice only during morning training. In the subsequent two experiments, we investigated two types of interference, motor and cognitive, and found that memory was more susceptible to motor interference in the morning. Furthermore, the deterioration in performance seemed to arise from a conflict between the declarative and procedural memory systems required for our task. Additionally, we provided neurophysiological evidence for these different consolidations by demonstrating a different modulation of corticospinal excitability immediately post-practice, which varied depending on the time of day.
In the 3rd study, we emphasized the importance of daily activity in consolidation. We observed that engaging in motor activity before morning practice prevented performance deterioration during the day, whereas remaining inactive until afternoon practice resulted in worsened performance. We suggested that, while sleep is advantageous for the consolidation of previously acquired skills, it may hinder the consolidation of subsequent learning due to the inactivity it promotes.
In our final 4th study, we showed that the time of day also influenced consolidation following a mental practice. Although the acquisition and consolidation processes differ between physical and mental practice, we found that consolidation was also better in the afternoon than in the morning.
Overall, the results of this thesis underscore the importance of considering the time of day and the activities undertaken before learning when designing optimal training programs and rehabilitation protocols.
... According to Banks and Dinges [6], partial sleep deprivation can occur in three ways: (1) preventing the normal progression and sequencing of sleep stages from being physiologically consolidated relative to time in bed, called sleep fragmentation; (2) loss of specific physiological sleep stages, referred to as selective sleep stage deprivation, which can occur if sleep fragmentation is isolated to a specific sleep stage (such as when apnoeic episodes disrupt primarily one stage of sleep such as REM sleep, or when medications suppress a specific sleep stage); and (3) sleep restriction, which is also referred to as sleep debt, which is characterised by reduced sleep duration. Reduced sleep over several days (hence sleep disturbance by restriction) is a common occurrence in athletic and non-athletic populations, resulting in reduction in sleep quality and quantity [7][8][9]. Athletes might experience sleep loss for many reasons, such as during daily training where early rising or retiring late at night is required, apprehension the night before competition and sleeping in unfamiliar surroundings. Combined with time zone transition disturbance and environmental and psychological factors, athletes are susceptible to achieving <7 h of sleep per night [10]. ...
Purpose: Purpose: We examined whether supplementation of zinc magnesium aspartate (ZMA) in two groups of males, either partially sleep-restricted (4 h) or with habitual sleep (8 h) for 2 nights, was beneficial for sleep and subsequent morning Stroop performance. Methods: Participants were randomly allocated to two independent groups who either had 4 h (33 males) or 8 h (36 males) sleep for two nights. Using a double-blinded, randomised counterbalanced design, they then completed five sessions, (i) two familiarisation sessions including 7 days of sleep and dietary intake, (ii) three conditions with 4 h or 8 h sleep and either NoPill control (NoPill), placebo (PLAC) or ZMA (ZMA). Sleep was assessed by actimetry and sleep questionnaires, and cognitive performance was assessed by the Stroop test. The data were analysed using a general linear model with repeated measures. Results: A main effect for “sleep” (4 or 8 h) was found, where more opportunity to sleep resulted in better “sleep” metrics (both objective and subjective) as well as better Stroop scores (lower colour-interference and word-interference scores and lower error in words). No main effect for “Pill” was found other than the mood state depression, where subjective ratings for the PLAC group were lower than the other two conditions. Interactions were found in anger, ease to sleep and waking time. Conclusion: Having 8 h opportunity to sleep resulted in better “sleep” metrics as well as better Stroop scores compared to 4 h. Supplementation of ZMA for 4 or 8 h for 2 nights had no effect on subsequent morning cognitive performance but reduced sleep or total sleep time by ~0.46 h compared to the other conditions. An interaction was found where sleep time was reduced by ~0.94 h in the ZMA group in the 8 h condition compared to NoPill or PLAC.
... Power can be positively affected by various warm-up protocols (Fradkin et al., 2010;Miguel Silva et al., 2018), post-activation potentiation protocols (Dobbs et al., 2019;Králová et al., 2018), or supplementation (Martinez et al., 2022). Strength performance can even be affected by primary physiological needs such as sleep (Craven et al., 2022), water intake (McCartney et al., 2017), food intake (Henselmans et al., 2022), or circadian rhythms (Ayala et al., 2021;Thun et al., 2015). However, it is still unknown how power output is affected by the most basic physiological need -breathing. ...
Problem Statement: Currently, there is a lack of evidence regarding the influence of various breathing conditions on specific strength parameters. Several studies have primarily focused on the health aspects of breathing through the nose versus the mouth. The purpose of this study is to investigate how specific breathing conditions affect explosive power performance. Approach: Fifty male college students performed 5 sets of 3 repetitions of squat jumps (SJ) under three breathing conditions: exhaling through the nose (NE), exhaling through the mouth (ME), and breath hold after inhale (BH). The best performance attained under each breathing condition (SJmax) as well as the average performance of the three best attempts under each condition (referred to as SJave) were recorded. Additionally, the participants' natural breathing pattern (NBP) was identified to assess whether the best results were achieved under it. A repeated measures ANOVA method and parametric paired t-test were used to identify differences in SJmax and SJave among various breathing conditions. The effect size was evaluated using Cohen's d. The Chi-squared test was employed to establish a relationship between SJmax, SJave, and NBP. Results: The ANOVA analysis revealed significant differences between the selected breathing conditions in both SJmax (p = 0.047) and SJave (p = 0.001). In the context of SJmax, both ME and BH led to significantly higher results than NE (NE < ME, p = 0.047, d = 0.29; NE < BH, p = 0.02, d = 0.34). Similarly, ME and BH also achieved significantly higher SJave results (NE < ME, p = 0.003, d = 0.45; NE < BH, p < 0.001, d = 0.53). Chi-squared analysis revealed a significant relationship between NBP and both SJmax (ꭕ² = 6.30, p = 0.043) and SJave (ꭕ² = 6.66, p = 0.036). Conclusion: The NE breathing condition can significantly lower squat jump performance compared to ME or BH in individuals who do not use NE in their training practice. Best squat jump performance is frequently achieved under NBP. However, selected breathing conditions may have a significant, yet likely minor effect on squat jump performance.
... dependent on the local timing of performance (Thun et al., 2015). Decision-making, task execution speed, and accuracy are all impacted by poor sleep quality (Troynikov et al., 2018). ...
The athlete's stamina supports sports performance, but stamina is supported by various things, one of which is the quality of the athlete's sleep during recovery. This study aims to determine the effect of sleep quality on football performance. The method used in this research is descriptive quantitative with a correlational approach. The sampling technique used was purposive sampling with several considerations, including football school students aged 13-15 years actively participating in football school activities and students are permitted to take part in research from a total population of 10 students consisting of 2 students aged 13 years, six students aged 14 years and two students aged 15 years. The research instruments are PSQI to determine sleep quality and GPAI to assess performance. Based on calculations and data analysis, an average PSQI score of 4.1 was obtained, and the average GPAI score for the criteria included SE 3.4, DM 3.1, and SP 3.6. Based on the correlation value calculation, it was found that there was a negative correlation with a moderate strength of -0.502 for PSQI and SE. In contrast, the correlation value between PSQI, DM, and SP had weak strength and was also harmful to SE at -0.305 but positive for SP, namely 0.255. Conclusion: The influence of sleep quality on football performance has a significant relationship, but the level of influence is at a medium or even low level.
... It inextricably linked human health with natural and social rhythms, in the system of influence of which he is throughout his life [11,12]. According to B.S. Alyakrinsky and O.G. Gazenko noted that the phase mismatch of the body's circadian rhythms with physical and social time sensors (in conditions, for example, evening and night work shifts) constantly accompanied by desynchronosis with disruption of the body's circadian system, designed for 24 hours of work [13,14,15,16,17]. ...
Human health, the development of social roles, inextricably linked with his behavior. Dissatisfaction with basic needs, such as the need for security, love, respect, self-respect, identity and self-actualization, leads to diseases and various disorders that affect the health of athletes and their sports achievements. During a competition, the effects of the circadian rhythms and the power of harmonics on the heart rate variability of skydivers were studied. People reveal the level and features of their self-actualization. The data obtained showed that during the acrophase of circadian rhythms in male skydivers, activation of mental processes is noted. This phenomenon is reliably associated with the need for cognition and spatial orientation. In the bathyphase of the competitive period, they showed a decrease in-group of synchronization, an increase in individual and cross-adaptive response. In female skydivers during the competitive period, according to the circadian rhythm indicators in the bathyphase, the need for protection and support revealed, which show psycho-emotional stress and a stable parasympathetic influence on the control of heart rhythm regulation. Group asymmetric synchronization of harmonic powers also noted. The results of the study of circadian rhythms showed a biorhythmological relationship between self-actualization of the personality of athletes and indicators of heart rate variability.
... Muscle strength assessments of the knee extensors included (in chronological order): (1) MVIC, (2) submaximal voluntary isometric contractions, (3) ITT, and (4) maximal effort concentric isokinetic (300-60° s −1 ) knee extension. All testing was completed between the hours of 07:00 and 11:00 to control for potential diurnal variations in muscle strength (Bambaeichi et al. 2005;Thun et al. 2015). ...
Acute sleep restriction (SR) reduces strength through an unknown mechanism. Purpose: To determine how SR affects quadriceps contractile function and recruitment. Methods: Eighteen healthy subjects (9 M, 9F, age 23.8 ± 2.8y) underwent isometric (maximal and submaximal), isokinetic (300–60°·s⁻¹), and interpolated twitch (ITT) assessment of knee extensors following 3d of adequate sleep (SA; 7–9 h·night⁻¹), 3d of SR (5 h·night⁻¹), and 7d of washout (WO; 7-9 h·night⁻¹). Results: Compared to SA (227.9 ± 76.6Nm) and WO (228.19 ± 62.9Nm), MVIC was lesser following SR (209.9 ± 73.9Nm; p = 0.006) and this effect was greater for males (− 9.8 v. − 4.8%). There was no significant effect of sleep or sleep x speed interaction on peak isokinetic torque. Peak twitch torque was greater in the potentiated state, but no significant effect of sleep was noted. Males displayed greater potentiation of peak twitch torque (12 v. 7.5%) and rate of torque development (16.7 v. 8.2%) than females but this was not affected by sleep condition. ITT-assessed voluntary activation did not vary among sleep conditions (SA: 81.8 ± 13.1% v. SR: 84.4 ± 12.6% v. WO 84.9 ± 12.6%; p = 0.093). SR induced a leftward shift in Torque-EMG relationship at high torque output in both sexes. Compared to SA, females displayed greater y-intercept and lesser slope with SR and WO and males displayed lesser y-intercept and greater slope with SR and WO. Conclusions: Three nights of SR decreases voluntary isometric knee extensor strength, but not twitch contractile properties. Sex-specific differences in neuromuscular efficiency may explain the greater MVIC reduction in males following SR.
... Sleep-related impairment, which captures compromised daytime functioning through sleepiness, was significantly worsened during the race period compared to pre-and post-race periods. This pattern of heightened sleep-related impairment during the race period was significant across both Race 1 and Race 2. In agreement with previous literature, a similar pattern of greater compromise during the race period (i.e., acute chronic sleep deprivation) was also seen for the cognitive function (Filardi et al., 2020;Saugy et al., 2013;Thun et al., 2015). It is possible that adventure racing athletes become 'desensitized' or their self-awareness of changes in cognitive function is diminished during races, given that prolonged periods of sleep deprivation in a natural environment setting, under conditions of near constant exertion, culminating in a significant lack of recovery time, are a routine part of adventure racing. ...
The aim of this study was to investigate sleep‐wake behavior and gain insights into perceived impairment (sleep, fatigue, and cognitive function) of athletes competing in two international multi‐day adventure races. Twenty‐four athletes took part across two independent adventure races: Queensland, Australia and Alaska, USA. Individual sleep periods were determined via actigraphy, and racers self‐reported their perceived sleep disturbances, sleep impairment, fatigue and cognitive function. Each of these indices was calculated for pre‐, during‐ and post‐race periods. Sleep was severely restricted during the race period compared to pre‐race (Queensland, 7:46 [0:29] vs. 2:50 [1:01]; Alaska, 7:39 [0:58] vs. 2:45 [2:05]; mean [SD], hh:mm). As a result, there was a large cumulative sleep debt at race completion, which was not ‘reversed’ in the post‐race period (up to 1 week). The deterioration in all four self‐reported scales of perceived impairment during the race period was largely restored in the post‐race period. This is the first study to document objective sleep‐wake behaviors and subjective impairment of adventure racers, in the context of two geographically diverse, multi‐day, international adventure races. Measures of sleep deprivation indicate that sleep debt was extreme and did not recover to pre‐race levels within 1 week following each race. Despite this objective debt continuing, perceived impairment returned to pre‐race levels quickly post‐race. Therefore, further examination of actual and perceived sleep recovery is warranted. Adventure racing presents a unique scenario to examine sleep, performance and recovery.
... In the RES modality, three types of restrictions were imposed to vary the usual game conditions: (A) Motor, restricting players to a maximum of three bounces to be able to move toward the basket in each offensive possession; (B) Temporal, restricting offensive possessions to 5 s to conclude their attack, in case of not finishing their attack action in that time they lost possession of the ball in favor of the defense; and (C) Spatial, restricting offensive displacements in a central area of the half court of 14 × 4.9 meters. The following measures were taken to ensure control of the experimental conditions: (1) Sessions were scheduled at the same time of day for each pair of participants, thus mitigating the effect of diurnal variations (Thun et al., 2015); (2) A required rest of at least 72 h between sessions was established for adequate recovery; (3) The same model of ball was used during the experimental sessions, with differentiated sizes for boys (size 7) and girls (size 6). In cases of mixed pairs, there was a researcher in charge of alternating the ball between attack phases to maintain equity; and (4) The intensity of the physical load was closely monitored and controlled by applying the training load methodology of Edwards (1993) (detailed in Section 2.4.2, ...
Background
Executive functions, notably inhibition, significantly influence decision-making and behavioral regulation in team sports. However, more research must be conducted on individual player characteristics such as experience and motor skills. This study assessed how accumulated practical experience moderates inhibition in response to varying task difficulty levels.
Methods
Forty-four university students (age: 20.36 ± 3.13 years) participated in this study with two sessions: one followed standard 1 × 1 basketball rules (“Regular Practice”), while the other imposed motor, temporal, and spatial restrictions (“Restriction Practice”). Functional difficulty was controlled by grouping pairs with similar skill levels. Flanker and Go-Nogo tasks were used.
Results
Increasing complexity worsened cognitive performance (inhibition). “Restriction Practice” showed a significantly slower and less accurate performance in both tests than “Regular Practice” (p < 0.001). Experience positively impacted test speed and accuracy (p < 0.001).
Conclusion
In sports, acute cognitive impacts are intrinsically linked to the task’s complexity and the athlete’s cognitive resources. In this sense, it is essential to adjust individually the cognitive demands of the tasks, considering each athlete’s specific cognitive abilities and capacities.
... For example, the mainland of the United States of America has five different time zones (Pacific, Mountain, Arizona Mountain, Central, and Eastern), and professional athletes competing in this country are frequently exposed to this type of time-zone-shifting travels during a competition season (Huyghe et al. 2018). These time zone changes in a short period of time cause CR phase shifts and these phase shifts affect sportive performance (Thun et al. 2015). For this effect to disappear, the internal clock needs to fully adapt to the real (local) time, which requires an adaptation time of approximately 24 hours per one-hour time zone change (Leota et al. 2022). ...
Professional athletes competing in the NBA are frequently exposed to time-zone-shifting travels. These time zone changes may cause circadian rhythm (CR) phase shifts and these shifts affect sportive performance. The aim of this study was to investigate the effects of CR phase shifts on the performance of NBA teams. 25016 regular season games across 21 consecutive seasons were included in the CR phase shift calculations. To examine the CR phase shift effect on team performance, teams were divided into three groups regarding Coordinated Universal Time (UTC): the same internal UTC as the local UTC (LS); the internal UTC ahead of the local UTC (LA); and the internal UTC behind the local UTC (LB). With a different approach, teams were divided into another three categories: the same internal UTC as its opponent’s internal UTC (OS); the internal UTC ahead of its opponent’s internal UTC (OA); and the internal UTC behind its opponent’s internal UTC (OB). 24985 game data were used to compare these groups in terms of 25 variables. Statistical analyses were conducted separately for home and away teams. For home games, it was found that LA and OA are the most and LB is the least successful group in winning and scoring performances. For away games, it was determined that LS is the most advantageous group with the best winning percentage. These results revealed that teams from more west may have a CR advantage in regular season home games. However, it is thought that the performance of away teams depends more on travel fatigue than CR phase shifts.
... Standing height (±0.1 cm) was measured using a wall-mounted stadiometer (seca 206, seca), and body mass (±0.1 kg) was measured using digital scales (Kern MPE-E, KERN & SOHN GmbH) according to the guidelines of International Society for the Advancement of Kinanthropometry as part of the skeletal age assessment. All assessments were conducted at the same time of the day between 5 and 7 PM to reduce the effect of circadian rhythm upon anthropometric measurements and physical performance (40,48). ...
Purpose : To compute reference centiles for 5- and 30-m sprint times relative to chronological and skeletal age in youth soccer players. Subsequently, to compare individual’s sprint performance scores derived from the chronological and skeletal age reference centiles. Methods : Sprint times were collected for a sample of male U11 to U19 soccer players (n = 1745 data points). Skeletal age data were available for a subsample (n = 776 data points). Reference centiles were fitted using generalized additive models for location, scale, and shape. Individual z scores relative to chronological and skeletal age reference centiles were computed and compared for each maturity group (late, on-time, early, and very early) using standardized mean differences (SMD). Results : Reference centiles for chronological age increased more rapidly between 10.5 and 15.5 years, while reference centiles for skeletal age increased more rapidly between 13.0 and 16.5 years. Differences in chronological and skeletal z scores for very early (SMD: −0.73 to −0.43) and late (SMD: 0.58 to 1.29) maturing players were small to large, while differences for early (SMD: −0.30 to −0.19) and on-time (SMD: 0.16 to 0.28) were trivial to small. Conclusion : Reference centiles provide a valuable tool to assist the evaluation of sprint performance in relation to chronological and skeletal age for talent identification purposes in youth soccer players.
... Furthermore, in the present study we found that the maximal torque parameters (PT and RTD) were not affected by 24 h of sleep deprivation. These results are in line with the literature that suggests that tasks requiring short-term high-power output (anaerobic and maximal strength performance) seem to be unaffected by sleep deprivation (Fullagar et al. 2015;Skurvydas et al. 2020a, b;Thun et al. 2015). Temesi et al. (2013) found no effect of one night of sleep deprivation on maximal voluntary isometric contraction of the knee extensors. ...
The regularity of the fluctuations present in torque signals represent the adaptability of the motor control. While previous research showed how it is affected by neuromuscular fatigue and ageing, the underlying mechanisms remain unclear. It is currently under debate whether these changes are explained by central or peripheral neuromuscular mechanisms. Here, we experimentally manipulated the sleep of thirteen young adults through a supervised 24 h-sleep deprivation protocol. This study aimed to investigate the effect of sleep deprivation on the regularity of torque fluctuations, and other standard torque-related outcomes (Peak Torque – PT – and Rate of Torque Development – RTD). The participants were asked to perform knee extension maximal voluntary contractions (MVC) and submaximal knee extensions at 40% of MVC for 30 s. PT and RTD were calculated from the MVC and the regularity of the torque fluctuations was determined on the submaximal task through Sample Entropy (SampEn). In addition, rate of perceived effort (RPE) was collected. We found no significant changes in PT and RTD. The regularity of torque fluctuations significantly increased (i.e., a decrease in SampEn) after 24 h-sleep deprivation (PRE = 1.76 ± 0.268, POS24 = 1.71 ± 0.306; p = 0.044). Importantly, we found a negative correlation between RPE and SampEn relative changes after sleep deprivation. This study brings new insights towards the understanding of the underlying mechanisms that explain changes in torque fluctuations, demonstrating that these changes are not limited to neuromuscular processes but are also likely to be affected by other domains, such as psychological profile, which can indirectly affect the neural drive to the muscles.
... In order to minimize confounding factors of the training and sex effects, only strength-trained male team sports athletes were recruited. The experiment was conducted in the same gym at the same time of the day using identical equipment for each subject to eliminate the environmental and circadian effects [31]. The data was collected in six sessions: in the first two sessions, 1RM weight for backsquat exercise for each participant was determined along with body composition measurements. ...
Aims: The purpose of this study was to investigate the acute effects of a heavy back-squat exercise on change of direction performance. Methods: Eighteen male team sports athletes (age 23.6 ± 3.3y) performed T-test and 505 Test in consecutive sessions with and without heavy back-squat exercise applied as three sets of three repetitions at 90% of 1 RM as a conditioning activity in a randomized order. Change of direction tests were repeated at time intervals of 15 seconds, 2, 4, 8, 12 and 15 minutes after those two different conditions. Results: In 505 Test, no significant condition effect, time effect or condition–time interaction were found (P > 0.05). In T-test, there was no significant condition effect (P > 0.05); however, time effect and condition × time interaction were significant (P < 0.05). Conclusion: The findings of this study showed that the conditioning activity applied to elicit post-activation performance enhancement did not have any significant effect on 505 Test; on the contrary, in T-Test, the conditioning activity led to fatigue, rather than a potentiation effect.
... Partial sleep loss (a 2-3 h reduction of sleep per night compared to that habitually taken in a 24 h period) over several days is a common occurrence in athletic and non-athletic populations [15][16][17]. Within athletes, this is attributed to high training and competition demand whereby a session might involve early rising or retiring late at night. Combined with time zone transition disturbance, environmental and psychological factors, athletes are susceptible to achieving <7 h of sleep per night. ...
Purpose: We examined whether supplementation of zinc magnesium aspartate (ZMA), while partially sleep deprived, was beneficial to sleep quality and subsequent morning (07:00 h) submaximal weightlifting. Methods: Using a double-blinded, randomized counterbalanced design, sixteen trained males were recruited and completed six sessions: (i) one repetition max (1 RM) for bench press and back squat; (ii) two familiarisation sessions; (iii) three conditions with 4 h sleep and either: ZMA, placebo (PLA), or NoPill control (NoPill). Submaximal exercise session consisted of three repetitions at 40, 60 and 80% of 1 RM for bench press and back squat. Average power (AP), average velocity (AV), peak velocity (PV), displacement (D) and time-to-peak velocity (tPV) were recorded using MuscleLab linear encoders. Data were analysed using a general linear model with repeated measures and linear correlation. Results: No significant main effect for condition was found for performance values or subjective ratings of fatigue. Main effect for "load" on the bar was found, where AP and tPV values increased with load (p < 0.05). No significant relationship between dose of zinc or magnesium ingested and change in performance for 80% 1 RM power-outputs was found. Conclusion: Supplementation of ZMA for two nights of partial sleep deprivation had no effect on sleep or subsequent morning performance.
For this study, total of 26 (13 male and 13 female) subjects were selected from the Department of Physical Education, Central University of Kashmir, age ranged between 23 to 27 years. Non-Probability sampling such as purposive sampling was used in the present study. In the present study chronotype was selected as the Independent Variable whereas Speed, Agility and Lower body explosive strength was considered as the dependent variables. Chronotype is understood to reflect a spectrum of behaviors ranging from an extreme preference for morning activity to an extreme preference for evening activity. Horneostberg, (1976) morning - evening question was used to find out the chronotype of the athletes. All the tests were conducted and administered at different times in a day. i.e., morning from 9.30 AM to 10:30 AM and evening between 03:00 pm to 04:00 pm. The obtained data was analyzed by applying the descriptive statistics and paired “t” were worked out and the results have been presented in different tables. . Therefore, it was concluded that mean differences in the explosive strength and agility in morning and evening was statistically significant and it was also concluded that mean differences in the morning 50m sprint and evening 50m sprint were not statistically significant.
Maximal gross-muscular performance shows a daily variation in adult males, however, effects of sleep loss on circadian rhythms of gross-muscular tasks with a high skill element such as the standing broad jump is less well established, and differences between biological sex may exist. Thirty-one males and 24 females volunteered. Participants were familiarised with tests before completing two conditions i) Normal (N) retires at 23:30, rising at 07:30 h the night before testing, and ii) Sleep deprivation (SD) retiring at 03:00, rising at 07:30 h, administered in a randomised counterbalanced-fashion. Participants having had 8- or 4.5-h opportunity to sleep, entered the laboratory at 08:00 h and sublingual temperatures, tiredness, and alertness were measured. Thereafter, volunteers completed a warm-up (3 jumps at 40, 60, and 80% max-effort) and then performed jumps. This schedule was replicated at 12:00, 16:00, 20:00, 24:00, and 04:00 h on the same day. Participants were more tired and less alert in the partial sleep deprivation condition, and time-of-day effects were evident in all variables with peaks in jump length coinciding with temperature and alertness (Ф15:44-18:24 h). Females, however, showed a preference for an ~1 h earlier peak in tiredness (mediated in the SD rather than N), with a lower mesor and/or amplitudes in alertness and jump performance than males. The results of the current investigation have important implications for athletes, particularly females suffering sleep loss, regarding strategies to cope with early peaks in tiredness and physical training demands.
Sleep is vital for the maintenance of physical and mental health, recovery and performance in athletes. Sleep also has a restorative effect on the immune system and the endocrine system. Sleep must be of adequate duration, timing, and quality to promote recovery following training and competition. Inadequate sleep adversely impacts carbohydrate metabolism, appetite, energy intake and protein synthesis affecting recovery from the energy demands of daily living and training/competition related fatigue. Sleep’s role in overall health and wellbeing has been established. Athletes have high sleep needs and are particularly vulnerable to sleep difficulties due to high training and competition demands, as such the implementation of the potential nutritional interventions to improve sleep duration and quality is commonplace. The use of certain nutrition strategies and supplements has an evidence base i.e. carbohydrate, caffeine, creatine, kiwifruit, magnesium, meal make-up and timing, protein and tart cherry. However, further research involving both foods and supplements is necessary to clarify the interactions between nutrition and the circadian system as there is potential to improve sleep and recovery. Additional research is necessary to clarify guidelines and develop products and protocols for foods and supplements to benefit athlete health, performance and/or recovery. The purpose of this review is to highlight the potential interaction between sleep and nutrition for athletes, and how these interactions might benefit sleep and/or recovery.
In the more classical teaching of Neurophysiology, there is an obvious focus on pathologies of the nervous system (in its different aspects: central, peripheral and autonomic).This chapter therefore seems to us to be a unique and pertinent moment for reflection, as it aims to systematise how the various specific areas of Neurophysiology can be related to physical exercise, thinking above all about what expertise can be transferred from one area of speciality to another, creating knowledge that can be applied in the future and, above all, increasing health literacy in these professionals. This chapter will cover the EEG, EMG, evoked potentials, sleep, and urodynamic.
Study objectives:
While previous research has primarily focused on the immediate effects of concussion within the first year post-injury, this study examines the persistent effects of concussion on subsequent sleep quality in adolescent soccer players.
Methods:
This study utilized a cross-sectional design, recruiting a convenience sample of adolescent athletes from US Youth Soccer camps. Participants completed a self-reported questionnaire including the Pittsburgh Sleep Quality Index (PSQI) to assess their sleep quality. Athletes were also asked to report sport participation information, any past occurrence of concussion or knee injury, and any sport-related injury in the past 12 months. Independent Samples t-tests were performed to identify significant differences in PSQI scores between injured and non-injured participants.
Results:
A total of 177 participants (103 male, 14.61±1.88 years) were included in the analysis. The concussion injury group exhibited later bedtimes (difference: 0.32±0.05 hours; p=0.047), fewer hours of sleep (difference: 0.56±0.11 hours, p=0.015), and more frequent sleep disturbances (p=0.012). Furthermore, these athletes reported lengthened sleep latency (difference: 2.55±3.36 minutes, p=0.016) and higher levels of daytime dysfunction (p=0.041) following their concussion injuries. Moreover, athletes in the concussion injury group displayed worse sleep quality scores (difference: 0.42±0.06, p<0.001) and higher total PSQI scores (difference: 1.91±0.41, p<0.001). No significant differences were found based on past knee injury or sport-related injury in the past 12 months.
Conclusions:
These findings suggest the need for targeted interventions aimed at improving sleep quality in adolescent athletes with a history of concussion.
Objectives
Develop the Markov Index Load State (MILS) model, based on hidden Markov chains, to assess athletes’ workload responses and investigate the effects of menstrual cycle (MC)/oral contraception (OC), sex steroids hormones and wellness on elite athletes’ training.
Methods
On a 7-month longitudinal follow-up, daily training (volume and perceived effort, n=2200) and wellness (reported sleep quality and quantity, fitness, mood, menstrual symptoms, n=2509) data were collected from 24 female rowers and skiers preparing for the Olympics. 51 MC and 54 OC full cycles relying on 214 salivary hormone samples were analysed. MC/OC cycles were normalised, converted in % from 0% (first bleeding/pill withdrawal day) to 100% (end).
Results
MILS identified three chronic workload response states: ‘easy’, ‘moderate’ and ‘hard’. A cyclic training response linked to MC or OC (95% CI) was observed, primarily related to progesterone level (p=8.23e-03 and 5.72e-03 for the easy and hard state, respectively). MC athletes predominantly exhibited the ‘easy’ state during the cycle’s first half (8%–53%), transitioning to the ‘hard’ state post-estimated ovulation (63%–96%). OC users had an increased ‘hard’ state (4%–32%) during pill withdrawal, transitioning to ‘easy’ (50%–60%) when on the pill. Wellness metrics influenced the training load response: better sleep quality (p=5.20e-04), mood (p=8.94e-06) and fitness (p=6.29e-03) increased the likelihood of the ‘easy’ state. Menstrual symptoms increased the ‘hard’ state probability (p=5.92e-02).
Conclusion
The MILS model, leveraging hidden Markov chains, effectively analyses cumulative training load responses. The model identified cyclic training responses linked to MC/OC in elite female athletes.
This chapter aims to illustrate the impact of sleep deprivation on athletic performance. Sleep research distinguishes between total, partial, and selective sleep deprivation. In rats, sleep deprivation of two to three weeks leads to death under experimental conditions. In humans, due to ethical reasons, only shorter periods of sleep deprivation have been studied. Here too, losses are primarily seen in cognitive performance, with microsleep episodes in particular reducing performance after sleep deprivation. In addition, there are negative changes in memory formation, pain perception, the immune system, and metabolism. The effects on motor skills such as strength and endurance are rather minor due to sleep deprivation. Various recommendations for action arise for sports practice, although various questions still need to be investigated.
Background: Currently, the scientific evidence available on plyometric training in young basketball players is limited. Objectives: The aim of this study was to analyze the effects produced by plyometric training over a period of 8 weeks, with a frequency of two weekly training sessions, combining vertical and horizontal force vectors. Methods: The study involved 28 young men (14.54 ± 0.6 years, a height of 182.76 ± 7.1 cm and a body weight of 68.05 ± 9.8 kg) high-level basketball players and aimed to investigate the effects of this training program on athletes at different maturational states, specifically based on their peak height velocity (PHV) and post-pubertal (post-PHV) stages. Results: Substantial improvements were achieved in the subjects who have carried out this type of plyometric training in all the parameters evaluated related to the improvement of the jump, linear speed and change of direction. Conclusions: Therefore, it is crucial to provide valuable information to trainers and physical trainers, enabling them to improve and individualize the conditioning work for optimal performance of their athletes.
The mood and sleep status influence subsequent physical performance. However, the relationship between these factors and the accuracy of hitting the mark in kyudo remains unexplored. This study aimed to compare the mood and sleep status of university kyudo athletes on days with higher and lower accuracy. A total of 15 university kyudo athletes (age, 20 ± 2 years; 11 men) participated in the study. Participants were instructed to shoot 20 arrows in the morning for two to three days, with the days of higher and lower accuracy subsequently determined and compared for mood and sleep status. Sleep status on the preceding day of the accuracy assessments was measured using the Nemuri SCAN, while mood status immediately before the accuracy assessments were measured using the Profile of Mood States 2nd Edition (POMS2). None of the study participants demonstrated consistent accuracy across all accuracy assessments. When a three-day accuracy assessment was administered, and consistent accuracy was demonstrated on two days, the average mood and sleep status from those two days were incorporated into the analysis. Results indicated that total sleep time and sleep quality were significantly lower on the day before the higher accuracy day than on the day before the lower accuracy day (P < 0.05). Additionally, the Vigor-Activity score of POMS2 was trending lower on the higher accuracy day than on the lower accuracy day (P = 0.09). These results suggest that kyudo athletes may perform better under sub-optimal mood and sleep conditions rather than optimal conditions.
Circadian rhythms in the physiological and behavioral processes of humans play a crucial role in the quality of living and also in the magnitude of success and failure in various endeavors including competitive sports. The rhythmic activities of the body and performance in sportspersons do have a massive impact on their every cutthroat competition. It is essential to schedule sports activities and training of players according to their circadian typology and time of peak performance for improved performance and achievement. In this review, the focus is on circadian rhythms and diurnal variations in peak athletic performance in sportspersons. Accuracy and temporal variability in peak performance in an individual could be attributed to various factors, namely chronotype, time of the day, body temperature, jetlag, hormones, and prior light exposure. Circadian rhythm of mood, alertness, T-core, and ultimately athletic performance is not only affected by sleep but also by circadian variations in hormones, such as cortisol, testosterone, and melatonin. There are, however, a few reports that are not consistent with the conclusions drawn in this review. Nevertheless, circadian rhythm and performance among sportspersons and athletes are important areas of research. This review might be useful to the managers and policymakers associated with competitive sports and athletic events.
Bu araştırma, 2021-2022 eğitim-öğretim yılı okul sporları yıldız kategorisinde dereceye girmiş sporcuların sabahçıl-akşamcıl durumlarına göre sosyal duygusal öğrenme beceri düzeylerinin belirlenmesi amacıyla yapılmıştır. Araştırmanın evrenini okul sporları yıldız kategorisi müsabakalarında, farklı spor branşında dereceye giren 13-15 yaş arası 588 sporcu, örneklemini ise araştırmaya gönüllü katılan 203 erkek (%48,9) 212 kadın (%51,1) olmak üzere toplam 415 sporcu oluşturmuştur. Veri toplama aracı olarak “Kişisel Bilgi Formu”, Sabahcıl-Akşamcıl Ölçeği ve “Sosyal Duygusal Öğrenme Ölçeği” kullanılmıştır. Kadın sporcuların sabahçıl-akşamcıl olma durumlarına göre sosyal duygusal öğrenme düzeyleri arasında anlamlı bir sonuç bulunmamışken (p>0,05) erkek sporcuların sabahçıl-akşamcıl olma durumlarına göre sosyal duygusal öğrenme düzeyleri arasında sabahçıl sporcular lehine anlamlı farklılık elde edilmiştir (p0,05). Araştırma sonucunda sabahçıl olan erkek sporcularda sosyal duygusal öğrenme becerileri düzeylerinin pozitif etkilendiği sonucuna ulaşılmıştır. Sporcuların psikolojik ve fizyolojik performansı ile birlikte sosyal duygusal öğrenme beceri gelişim performansını da artırmak için sabahcıl-akşamcıl olma durumlarına göre antrenman programlarının düzenlenmesi gerektiği söylenebilir.
Objetivo: Este estudo teve como objetivo analisar se existem diferenças na qualidade do sono entre lutadores de karatê amadores e profissionais. Metodologia: Dezenove lutadores de karatê masculinos participaram do estudo, sendo dez lutadores amadores (campeonatos regionais), com idade média de 32,3 ±11,2 anos e peso médio de 79,1 ±13,1 kg, e nove lutadores profissionais (campeonatos mundiais), com idade média de 26,8 ±10,5 anos e peso médio de 66,3 ±8,2 kg. Todos os voluntários responderam ao instrumento PSQI-Br, validado para o português brasileiro. O teste não paramétrico de Mann-Whitney U foi usado para análise estatística, com valor de p, valor U, escore Z e tamanho de efeito. Resultados e discussão: Houve diferença estatisticamente significativa no horário de dormir e na duração do sono, indicando resultados piores para lutadores profissionais de karatê. Não houve diferenças na qualidade geral do sono; no entanto, ambos os grupos foram classificados como tendo má qualidade do sono. Conclusão: Portanto, lutadores de karatê amadores e profissionais têm má qualidade do sono, o que gera vários fatores que afetam negativamente a saúde e o desempenho.
Aim
To study differences in total load exposure, wellness, and psychological variables in youth female ( N = 19) and male ( N = 20) national team football players during domestic and international playing periods, respectively.
Procedures
The players filled out questionnaires on well-being, stress, and resilience before and after both playing periods lasting 8 days each. The Hooper index was used to monitor daily wellness levels during both playing periods. The number of training sessions and matches were recorded, and the session rating of perceived exertion was collected. Training load, monotony, and strain were calculated. Daily measurements were used to evaluate in-period changes, and composite scores were used to describe differences between periods.
Results
The international compared to the domestic playing period was for both groups characterized by more matches played, longer field training session durations, and of fewer gym-based sessions ( P < 0.05). The male players increased total exposure time (25%; P < 0.05), monotony ( P < 0.001), and strain ( P < 0.001), which was not changed in the female players. Well-being decreased ( P < 0.05) during the international playing period in male players. Stress levels were higher ( P < 0.05) for both genders during the international compared to the domestic playing period. During the international playing period, positive correlations were found between the initial levels of stress, and the change in stress ( P = 0.03; r 2 = 0.12), and between the changes in total load and changes in well-being ( P = 0.02; r 2 = 0.12), whereas a negative correlation was found between the changes in wellness and stress ( P = 0.03; r 2 = 0.14).
Conclusion
A playing period characterized by increased match focus, longer field training sessions, and fewer gym-based training activities may lead to changes in the physical and mental profiles of youth national team football players. Alterations to load exposure and wellness may influence mental health. Players with high initial stress levels may be subjected to greater changes compared to other players. Sports scientists and medical staff may benefit from initiating structured monitoring systems to track alterations in physical load and mental health in youth national team players.
Background: Dart sport has become a sport that has recently become widespread among sports branches and its popularity is increasing rapidly day by day. With this popularization, research on darts is increasing. It is stated that athletes can do the training they do at any time of the day with a much better performance at a different time, as in many changing conditions. In addition, at a different time of day, fatigue may be reached later or recovery may occur more quickly. For these reasons, knowing the effect of training at different times of the day is important for both the coach and the athlete. Objectives: The aim of this study was to investigate the effect of different times of the day on throwing performance in darts, an indoor skill in which focus, attention, concentration are at the forefront and environmental factors are less effective than outdoor skill. Methods: In this study, 16 dart athletes (8 boys, 8 girls) with a sport age of 2 - 3 years and an age of 12 - 14 years, who did not have any health problems in Mardin province, participated voluntarily: 2 m and 2.37 m from two different distances at 8.00 and 17.00, 1 day apart. Before the dart throws, the Daily Rhythm Determination Scale for Children was administered to the participants. The center of the dartboard was placed at eye level for each subject. After the throws, the Perceived Difficulty Scale was applied. In the analysis examining the relationship between perceived degree of difficulty, morningness-eveningness and throwing, the subjects’ evening throwing scores and evening perceived degree of difficulty scores were examined; a negative and significant relationship was observed in the eveningist group (r = -1, P = 0.01). No significant relationship was observed in the morning group. Results: In the study, a statistically significant difference was found between the subjects’ morning and evening throws at 2 m and 2.37 cm. In both morning and evening groups, it was determined that the throwing performance increased in the evening measurements. Conclusions: As a result, this study concluded that there is an effect of time of day in dart sport and that dart throws made in the evening give better results than dart throws made in the morning. Based on these results, it is recommended that a program should be made by the coaches considering the school programs and daily routines to reduce the effect of time of day. It is thought that this study will be important for chronobiological researches to reveal the factors affecting performance as well as the effect of time of day in darts sport.
Bir basketbol maçını kazanabilmek için fiziksel, fizyolojik, psikolojik, biyomotor, bilişsel, teknik ve taktik özelliklerin gelişmiş olması gerekmektedir. Bu özelliklerin sirkadiyen ritimden etkilendiği, bu nedenle günün farklı saatlerinde söz konusu performansların değişebildiği bilinmektedir. Bu araştırmada, sirkadiyen ritmin 18 Yaş Altı Erkekler Basketbol Türkiye Şampiyonasına katılan takımların performanslarına olan etkisi incelenmiştir. Türkiye Basketbol Federasyonu resmi sitesinde açık erişimli olarak paylaşılan beş turnuvadaki 208 maçın istatistik verisi toplanmıştır. Araştırmaya sadece uzatmaya giden ya da 10 sayıdan az farkla biten 97 maç dahil edilmiştir. Bu maçlarda takımların istatistik verileri toplanmış ve her maç için takım başı birer veri seti olmak üzere toplamda 194 farklı takım istatistik verisi incelenmiştir. Sirkadiyen ritmin performansa etkisini incelemek için maç istatistikleri ile maç başlama saati arasındaki ilişki test edilmiştir. Ayrıca sabah ve akşam saatlerindeki maçların istatistikleri de birbirileriyle karşılaştırılmıştır. Korelasyon analizi sonucu iki sayılık deneme ve asist istatistiklerinin maç saati ile negatif; üç sayılık deneme, serbest atış deneme, başarılı serbest atış ve faul istatistiklerinin ise maç saatiyle pozitif korelasyon gösterdiği belirlenmiştir (p<0.05). Sabah ve akşam maçlarının karşılaştırılması sonucu ise saha içi deneme, iki sayılık deneme ve asist istatistiklerinin sabah maçlarında; serbest atış yüzdesi, serbest atış deneme, başarılı serbest atış ve faul istatistiklerinin ise akşam maçlarında daha fazla olduğu tespit edilmiştir (p<0.05). Ulaşılan bulgular ışığında akşam maçlarında şutör oyunculara verilen sürenin artırılması ve takımın önemli uzun oyuncularının faul problemine girme ihtimali göz önünde tutularak stratejik planlanmaların yapılması önerilmektedir. Sabah maçlarında ise kolay penetre yememek ve yenilen penetreleri daha etkili savunabilmek için taktik hazırlıkların planlanmış ve çalışılmış olması oldukça önemlidir.
Two experiments were conducted concerning diurnal variations in physical performance. Subjects were tested at 9 AM, 12 noon, and 3 PM on various physical parameters. Exp. 1 gave no significant differences among the three performances of grip strength and reaction times for 16 subjects. For seven subjects involved in Exp. 2, endurance ratios and torque accelerations, as recorded on a Cybex II, were used as criterion measures. A significant difference was found between the 9 AM and 3 PM performance of the flexion endurance ratio. No other differences were identified.
The aim of this study was to investigate the effects of sleep deprivation induced anxiety on anaerobic performance. Thirteen volunteer male physical education students completed the Turkish version of State Anxiety Inventory and performed Wingate anaerobic test for three times: (1) following a full-night of habitual sleep (baseline measurements), (2) following 30 hours of sleep deprivation, and (3) following partial-night sleep deprivation. Baseline measurements were performed the day before total sleep deprivation. Measurements following partial sleep deprivation were made 2 weeks later than total sleep deprivation measurements. State anxiety was measured prior to each Wingate test. The mean state anxiety following total sleep deprivation was higher than the baseline measurement (44.9 ± 12.9 vs. 27.6 ± 4.2, respectively, p = 0.02) whereas anaerobic performance parameters remained unchanged. Neither anaerobic parameters nor state anxiety levels were affected by one night partial sleep deprivation. Our results suggest that 30 hours continuous wakefulness may increase anxiety level without impairing anaerobic performance, whereas one night of partial sleep deprivation was ineffective on both state anxiety and anaerobic performance. Key pointsShort time total sleep deprivation (30 hours) increases state anxiety without any competition stress.Anaerobic performance parameters such as peak power, mean power and minimum power may not show a distinctive difference from anaerobic performance in a normal sleep day despite the high anxiety level induced by short time sleep deprivation.Partial sleep deprivation does not affect anxiety level and anaerobic performance of the next day.
The purpose of this study was to examine the test–retest reliability and circadian variability of an abbreviated, 15-s version of the Wingate Anaerobic Test (WAnT15). A total of 35 healthy, physically-active subjects (20.2 ± 3.6 years) performed two WAnT15 tests, 24 h apart (Reliability phase; n = 18), and on a different occasion performed morning and evening WAnT15 tests, (Circadian phase; n = 17). In the reliability phase, tests 1–2 differences and intra class correlations for peak power output (PPO) and mean power output (MPO) were 0.22% and 0.997 and 0.38% and 0.996, respectively. The fatigue index (FI) was not found reliable. In the circadian phase, only PPO significantly changed between morning and evening sessions (3.0%, p = 0.021). These findings suggest that the shortened WAnT15 is a highly reliable anaerobic power test with circadian variability
2 Abstract: The purpose of this study was to investigate diurnal variation in some specific skills performance and some physical fitness and physiological factors in soccer players. Twelve male soccer players (mean±SD; age 22.6±3 years; height 1.76±4.4 m; body mass 66.5±4.6 kg) participated in the study. Subjects performed some specific soccer skills and some physical fitness factors in one day. One test was carried out in the morning, between 7.00 and 9.00 and another one in the evening, between 19.00 and 21.00. A significant main effect of time of day was observed for oral temperature: the temperature in the evening was higher than morning (T= 2.83, P= 0.01). No significant time of day effect was found for hear rate (T= 1.72, P=0.11), systolic pressure (T=-0.67, P= 0.51) and diastolic pressure (T= 0.34, P= 73). A significant main effect of diurnal variation was found for sergeant jump (T= 4.98, P= 0.000), sit and reach (T= 4.1, P= 0.002), flexibility of right hip (T= 4.15, P= 0.002) and 20-m running (T=-4.27, P= 0.001): the values of these factors were better in the evening. A significant diurnal variation was found for dribbling (T= 3.55, P= 0.004), wall volley (T=2.83, P= 0.01), soccer chipping (T= 5.04, P=0.000) and Yeagley soccer test (T=-4.09, P= 0.02). No significant difference was found in penalty kick (P = 0.18). It can be concluded that there was a circadian rhythm in performance of soccer players.
The aim was to test the hypothesis that one night of sleep deprivation will impair pre-loaded 30 min endurance performance and alter the cardio-respiratory, thermoregulatory and perceptual responses to exercise. Eleven males completed two randomised trials separated by 7 days: once after normal sleep (496 (18) min: CON) and once following 30 h without sleep (SDEP). After 30 h participants performed a 30 min pre-load at 60% [VO(2 max) followed by a 30 min self-paced treadmill distance test. Speed, RPE, core temperature (T(re)), mean skin temperature (T(sk)), heart rate (HR) and respiratory parameters VO(2 max), VCO(2), VE, RER pre-load only) were measured. Less distance (P = 0.016, d = 0.23) was covered in the distance test after SDEP (6037 (759) 95%CI 5527 to 6547 m) compared with CON (6224 (818) 95%CI 5674 to 6773 m). SDEP did not significantly alter T(re) at rest or thermoregulatory responses during the pre-load including heat storage (0.8 degrees C) and T(sk). With the exception of raised VO(2) at 30 min on the pre-load, cardio-respiratory parameters, RPE and speed were not different between trials during the pre-load or distance test (distance test mean HR, CON 174 (12), SDEP 170 (13) beats min(-1): mean RPE, CON 14.8 (2.7), SDEP 14.9 (2.6)). In conclusion, one night of sleep deprivation decreased endurance performance with limited effect on pacing, cardio-respiratory or thermoregulatory function. Despite running less distance after sleep deprivation compared with control, participants' perception of effort was similar indicating that altered perception of effort may account for decreased endurance performance after a night without sleep.
The purpose of the present study was to determine the time-of-day effects in maximal anaerobic power and capacity and in blood lactate responses during and after a supramaximal exercise. Fourteen undergraduate male students participated in the Wingate Test at three time points: 09:00, 13:00 and 17:00 hours on separate days. Before each test subjects' body weight, oral temperature and resting heart rate and subjects' peak power and mean power during the Wingate test were determined. Blood lactate concentrations were determined before, immediately after and at 3rd, 5th and 7th min of passive recovery period. A significant circadian rhythm was found for oral temperature (p < 0.001) and for peak (p < 0.05) and mean (p < 0.05) powers respectively. No significant circadian variation was observed for body weight, resting heart rate and blood lactate concentrations between all measured time units (p > 0.05). It is concluded that a time-of-day effect was evident in maximal anaerobic power and capacity however this variation was not parallel with those of oral temperature. In addition a time-of-day effect did not exist for the blood lactate concentrations.
Regulation of circadian period in humans was thought to differ from that of other species, with the period of the activity
rhythm reported to range from 13 to 65 hours (median 25.2 hours) and the period of the body temperature rhythm reported to
average 25 hours in adulthood, and to shorten with age. However, those observations were based on studies of humans exposed
to light levels sufficient to confound circadian period estimation. Precise estimation of the periods of the endogenous circadian
rhythms of melatonin, core body temperature, and cortisol in healthy young and older individuals living in carefully controlled
lighting conditions has now revealed that the intrinsic period of the human circadian pacemaker averages 24.18 hours in both
age groups, with a tight distribution consistent with other species. These findings have important implications for understanding
the pathophysiology of disrupted sleep in older people.
The interest in the systematic study of the circadian typology (CT) is relatively recent and has developed rapidly in the two last decades. All the existing data suggest that this individual difference affects our biological and psychological functioning, not only in health, but also in disease. In the present study, we review the current literature concerning the psychometric properties and validity of CT measures as well as individual, environmental and genetic factors that influence the CT. We present a brief overview of the biological markers that are used to define differences between CT groups (sleep-wake cycle, body temperature, cortisol and melatonin), and we assess the implications for CT and adjustment to shiftwork and jet lag. We also review the differences between CT in terms of cognitive abilities, personality traits and the incidence of psychiatric disorders. When necessary, we have emphasized the methodological limitations that exist today and suggested some future avenues of work in order to overcome these. This is a new field of interest to professionals in many different areas (research, labor, academic and clinical), and this review provides a state of the art discussion to allow professionals to integrate chronobiological aspects of human behavior into their daily practice.
Light is the major synchronizer of circadian rhythms. In the absence of light, as for totally blind people, some variables, such as body temperature, have an endogenous period that is longer than 24 h and tend to be free running. However, the circadian rhythm of muscle strength and reaction time in totally blind people has not been defined in the literature. The objective of this study was to determine the period of the endogenous circadian rhythm of the isometric and isokinetic contraction strength and simple reaction time of totally blind people. The study included six totally blind people with free-running circadian rhythms and four sighted people (control group). Although the control group required only a single session to determine the circadian rhythm, the blind people required three sessions to determine the endogenous period. In each session, isometric strength, isokinetic strength, reaction time, and body temperature were collected six different times a day with an interval of at least 8 h. The control group had better performance for strength and reaction time in the afternoon. For the blind, this performance became delayed throughout the day. Therefore, we conclude that the circadian rhythms of strength and simple reaction time of totally blind people are within their free-running periods. For some professionals, like the blind paralympic athletes, activities that require large physiological capacities in which the maximum stimulus should match the ideal time of competition may result in the blind athletes falling short of their expected performance under this free-running condition.
It is perceived that long haul travel, comprising of rapid movement across several time zones is detrimental to performance in elite athletes. However, available data is equivocal on the impact of long haul travel on maximal explosive movements. The aim of this study was to quantify the impact of long haul travel on lower body muscle performance. Five elite Australian skeleton athletes (1 M, 4 F) undertook long haul flight from Australia to Canada (LH(travel)), while seven national team Canadian skeleton athletes (1 M, 6 F) acted as controls (NO(travel)). Lower body power assessments were performed once per day between 09:30 and 11:00 h local time for 11 days. Lower body power tests comprised of box drop jumps, squat jump (SJ) and countermovement jumps (CMJ). The LH(travel) significantly decreased peak and mean SJ velocity but not CMJ velocity in the days following long haul flight. CMJ height but not SJ height decreased significantly in the LH(travel) group. The peak velocity, mean velocity and jump power eccentric utilisation ratio for the LH(travel) group all significantly increased 48 h after long haul flight. Anecdotally athletes perceived themselves as 'jet-lagged' and this corresponded with disturbances observed in 'one-off' daily jumping ability between 09:30 and 11:00 h after eastward long haul travel from Australia to North America when compared to non-travel and baseline controls.
The present study was designed to evaluate time-of-day effects on electromyographic (EMG) activity changes during a short-term intense cycling exercise. In a randomized order, 22 male subjects were asked to perform a 30-s Wingate test against a constant braking load of 0.087 kg·kg(-1) body mass during two experimental sessions, which were set up either at 07:00 or 17:00 h. During the test, peak power (P(peak)), mean power (P(mean)), fatigue index (FI; % of decrease in power output throughout the 30 s), and evolution of power output (5-s span) throughout the exercise were analyzed. Surface EMG activity was recorded in both the vastus lateralis and vastus medialis muscles throughout the test and analyzed over a 5-s span. The root mean square (RMS) and mean power frequency (MPF) of EMG were calculated. Neuromuscular efficiency (NME) was estimated from the ratio of power to RMS. Resting core temperature, P(peak), P(mean), and FI were significantly higher (p < .05) in the evening than morning test (e.g., P(peak): 11.6 ± 0.8 vs. 11.9 ± 1 W·kg(-1)). The results showed that power output decreased following two phases. During the first phase (first 20s), power output decreased rapidly and values were higher (p < .05) in the evening than in the morning. During the second phase (last 10s), power decreased slightly and appeared independent of the time of day of testing. This power output decrease was paralleled by evolution of the MPF and NME. During the first phase, NME and MPF were higher (p < .05) in the evening. During the second phase, NME and MPF were independent of time of day. In addition, no significant differences were noticed between 7:00 and 17:00 h for EMG RMS during the whole 30 s. Taken together, these results suggest that peripheral mechanisms (i.e., muscle power and fatigue) are more likely the cause of the diurnal variation of the Wingate-test performance rather than central mechanisms.
To investigate the effects of sleep extension over multiple weeks on specific measures of athletic performance as well as reaction time, mood, and daytime sleepiness.
Stanford Sleep Disorders Clinic and Research Laboratory and Maples Pavilion, Stanford University, Stanford, CA.
Eleven healthy students on the Stanford University men's varsity basketball team (mean age 19.4 ± 1.4 years).
Subjects maintained their habitual sleep-wake schedule for a 2-4 week baseline followed by a 5-7 week sleep extension period. Subjects obtained as much nocturnal sleep as possible during sleep extension with a minimum goal of 10 h in bed each night. Measures of athletic performance specific to basketball were recorded after every practice including a timed sprint and shooting accuracy. Reaction time, levels of daytime sleepiness, and mood were monitored via the Psychomotor Vigilance Task (PVT), Epworth Sleepiness Scale (ESS), and Profile of Mood States (POMS), respectively.
Total objective nightly sleep time increased during sleep extension compared to baseline by 110.9 ± 79.7 min (P < 0.001). Subjects demonstrated a faster timed sprint following sleep extension (16.2 ± 0.61 sec at baseline vs. 15.5 ± 0.54 sec at end of sleep extension, P < 0.001). Shooting accuracy improved, with free throw percentage increasing by 9% and 3-point field goal percentage increasing by 9.2% (P < 0.001). Mean PVT reaction time and Epworth Sleepiness Scale scores decreased following sleep extension (P < 0.01). POMS scores improved with increased vigor and decreased fatigue subscales (P < 0.001). Subjects also reported improved overall ratings of physical and mental well-being during practices and games.
Improvements in specific measures of basketball performance after sleep extension indicate that optimal sleep is likely beneficial in reaching peak athletic performance.
The aim of this study was to observe how the combined effects of time-of-day and sleep deprivation impact motocross riders' physical abilities. Balance, flexibility and maximal anaerobic alactic power were tested across laboratory tests that required only one ability (stork stand test, sit-and-reach test, Abalakov test) or across field tests that concentrated on a particular ability (narrow board riding test, riding under a rod test, long jump riding test) to maximise the sensitivity of the assessments and the interpretability of findings. Eight motocross riders of confirmed level took part in test sessions set up at 0600 and 1800 hours following a normal night's sleep and a night of sleep deprivation, i.e. after 1, 13, 23 and 35 waking hours. On the one hand, the results confirmed the influence of time-of-day on riders' physical abilities, performances being better at 1800 hours than at 0600 hours after the normal night's sleep. On the other hand, as far as sleep deprivation effects are concerned, the results seemed to differ on the basis of the ability under consideration and the type of test that had been set up. Performance in the field tests still presented a diurnal fluctuation, whereas this improvement over the day did not occur for the performance in the laboratory tests. It seems that compensation mechanisms between the various abilities brought into play are set up in order to moderate the effects of the lack of sleep when riding.
AIM: The purpose of this study was to compare the explosive force and electromyographic (EMG) activity at three different times of the day. METHODS: Thirty healthy subjects took part in the study, and carried out two maximum isometric voluntary knee extensions to measure explosive force, through contractile impulse (CI) and rate of force development (RFD), and myoelectric signals from quadriceps muscles in the following periods: 07:30-09:30, 13:30-15:30 and 19:30-21:30 (called morning, afternoon and night respectively), on three non-consecutive days. RESULTS: The body temperature was lower in the morning than in the afternoon and night periods. The explosive force, evaluated through contractile impulse (CI) and rate of force development (RFD), was greater at night than in the morning, without differences in the myoelectric signal. CONCLUSION: The ability to produce explosive force varies throughout different times of the day without variation in muscular recruitment, indicating that peripheral and not neural mechanisms could be responsible for this variation.
The purpose of this study was to examine whether time of day variations in power output can be accounted for by the diurnal fluctuations existent in body temperature. 8 recreationally trained males (29.8±5.2 yrs; 178.3±5.2 cm; 80.3±6.5 kg) were assessed on 4 occasions following a: (a) control warm-up at 8.00 am; (b) control warm-up at 4.00 pm; (c) extended warm-up at 8.00 am; and, (d) extended warm-up at 4.00 pm. The control warm-up consisted of dynamic exercises and practice jumps. The extended warm-up incorporated a 20 min general warm-up on a stationary bike prior to completion of the control warm-up, resulting in a whole body temperature increase of 0.3±0.2°C. Kinetic and kinematic variables were measured using a linear optical encoder attached to a barbell during 6 loaded counter-movement jumps. Results were 2-6% higher in the afternoon control condition than morning control condition. No substantial performance differences were observed between the extended morning condition and afternoon control condition where body temperatures were similar. Results indicate that diurnal variation in whole body temperature may explain diurnal performance differences in explosive power output and associated variables. It is suggested that warm-up protocols designed to increase body temperature are beneficial in reducing diurnal differences in jump performance.
This investigation aimed to quantify the typical variation for kinetic and kinematic variables measured during loaded jump squats.
Thirteen professional athletes performed six maximal effort countermovement jumps on four occasions. Testing occurred over 2 d, twice per day (8 AM and 2 PM) separated by 7 d, with the same procedures replicated on each occasion. Jump height, peak power (PP), relative peak power (RPP), mean power (MP), peak velocity (PV), peak force (PF), mean force (MF), and peak rate of force development (RFD) measurements were obtained from a linear optical encoder attached to a 40 kg barbell.
A diurnal variation in performance was observed with afternoon values displaying an average increase of 1.5-5.6% for PP, RPP, MP, PV, PF, and MF when compared with morning values (effect sizes ranging from 0.2-0.5). Day to day reliability was estimated by comparing the morning trials (AM reliability) and the afternoon trials (PM reliability). In both AM and PM conditions, all variables except RFD demonstrated coefficients of variations ranging between 0.8-6.2%. However, for a number of variables (RPP, MP, PV and height), AM reliability was substantially better than PM. PF and MF were the only variables to exhibit a coefficient of variation less than the smallest worthwhile change in both conditions.
Results suggest that power output and associated variables exhibit a diurnal rhythm, with improved performance in the afternoon. Morning testing may be preferable when practitioners are seeking to conduct regular monitoring of an athlete's performance due to smaller variability.
The aim of this study was to determine the effects of 30 h of sleep deprivation on consecutive-day intermittent-sprint performance and muscle glycogen content.
Ten male, team-sport athletes performed a single-day "baseline" session and two consecutive-day experimental trials separated either by a normal night's sleep (CONT1 and CONT2) or no sleep (SDEP1 and SDEP2). Each session included a 30-min graded exercise run and 50-min intermittent-sprint exercise protocol, including a 15-m maximal sprint every minute and self-paced exercise bouts of varying intensities. Muscle biopsies were extracted before and after exercise during the baseline session and before exercise on day 2 during experimental trials. Voluntary force and activation of the right quadriceps, nude mass, HR, core temperature, capillary blood lactate and glucose, RPE, and a modified POMS were recorded before, after, and during the exercise protocols.
Mean sprint times were slower on SDEP2 (2.78±0.17 s) compared with SDEP1 (2.70±0.16 s) and CONT2 (2.74±0.15 s, P<0.05). Distance covered during self-paced exercise was reduced during SDEP2 during the initial 10 min compared with SDEP1 and during the final 10 min compared with CONT2 (P<0.05). Muscle glycogen concentration was lower before exercise on SDEP2 (209±60 mmol·kg dry weight) compared with CONT2 (274±54 mmol·kg dry weight, P=0.05). Voluntary force and activation were reduced on day 2 of both conditions; however, both were lower in SDEP2 compared with CONT2 (P<0.05). Sleep loss did not affect RPE but negatively affected POMS ratings (P<0.05).
Sleep loss and associated reductions in muscle glycogen and perceptual stress reduced sprint performance and slowed pacing strategies during intermittent-sprint exercise for male team-sport athletes.
The purpose of this study was to assess the evolution of pedaling kinetics and kinematics during a short-term fatigue cycling exercise at two times of day. Twenty active male subjects were asked to perform a 60-s Wingate test against a constant braking resistance during two experimental sessions at 06:00 and 18:00 hours, i.e., very close to the hours of core temperature values, which are, respectively, the lowest and the highest. The results showed that the fatigue index was higher (P<0.05) at 18:00 hours (71.4%) than at 06:00 hours (69.2%) and power output was higher (P<0.05) in the evening than in the morning during the first 20 s of the test, after which no difference was observed. Taken together, these results showed a greater progression of fatigue in the evening than in the morning. The diurnal variations in performance and fatigue were associated (P<0.001) with diurnal changes in cycling kinematic parameters, characterized by a reduction in the range of motion of the ankle angle in the evening. These findings show that a time-of-day effect on movement patterns occurs during an anaerobic cycling exercise and that this phenomenon has a direct influence on performance and fatigue.
The present study was designed to investigate if the suggested greater fatigability during repeated exercise in the afternoon, compared to the morning, represents a true time-of-day effect on fatigability or a consequence of a higher initial power. In a counterbalanced order, eight subjects performed a repeated-sprint test [10 x (6 s of maximal cycling sprint + 30 s of rest)] on three different occasions between: 08:00-10:00, 17:00-19:00, and 17:00-19:00 h controlled (17:00-19:00 h(cont), i.e., initial power controlled to be the same as the two first sprints of the 08:00-10:00 h trial). Power output was significantly (p < 0.05) higher for sprints 1, 2, and 3 in the afternoon than in the morning (e.g., sprint 1: 23.3 +/-1 versus 21.2 +/-1 W.kg(-1)), but power decrement for the 10 sprints was also higher in the afternoon. Based on the following observations, we conclude that this higher power decrement is a consequence of the higher initial power output in the afternoon. First, there was no difference in power during the final five sprints (e.g., 20.4 +/-1 versus 19.7 +/-1 W.kg(-1) for sprint 10 in the afternoon and morning, respectively). Second, the greater decrement in the afternoon was no longer present when participants were producing the same initial power output in the afternoon as in the morning. Third, electromyographic activity of the vastus lateralis decreased during the exercise (p < 0.05), but without a time-of-day effect.
The purpose of the present study was to examine the effects of active warm-up duration on the diurnal fluctuations in anaerobic performances. Twelve physical education students performed a medical stress test (progressive test up to exhaustion) and four Wingate tests (measurement of peak power [P(peak)], mean power [P(mean)], and fatigue index during an all-out 30 s cycling exercise). The tests were performed in separate sessions (minimum interval = 36 h) in a balanced and randomized design at 08:00 and 18:00 h, either after a 5 min (5-AWU) or a 15 min active warm-up (15-AWU). AWU consisted of pedaling at 50% of the power output at the last stage of the stress exhausting test. Rectal temperature was collected throughout the sessions. A two-way ANOVA (warm-up x time of day) revealed a significant interaction for P(peak) (F((1.11)) = 6.48, p < 0.05) and P(mean) (F((1.11)) = 5.84, p < 0.05): the time-of-day effect was significant (p < 0.001) in contrast with the effect of warm-up duration (p > 0.05). P(peak) and P(mean) improved significantly from morning to afternoon after both 5-AWU and 15-AWU, but the effect of warm-up duration was significant in the morning only. Indeed, the values of P(peak) or P(mean) were the same after both warm-up protocols in the afternoon. For rectal temperature, there was no interaction between time-of-day and warm-up duration. Rectal temperature before and after both the warm-up protocols was higher in the afternoon, and the effect of warm-up duration on temperature was similar at 08:00 and 18:00 h. In conclusion, the interpretation of the results of the anaerobic performance tests should take into account time-of-day and warm-up procedures. Longer warm-up protocols are recommended in the morning to minimize the diurnal fluctuations of anaerobic performances.
The aim of this study was to evaluate time-of-day effects on fatigue during a sustained anaerobic cycling exercise. Sixteen healthy male competitive cyclists were asked to perform a 60 s Wingate test against a braking load of 0.087 kg.kg body mass(-1) during two experimental sessions, which were set up either at 06:00 or 18:00 h in counterbalanced order. There was only one session per day with a recovery period of at least 36 h between the two sessions. Each subject was trained to perform the test. The body mass used to determine the braking load was that of the first test session for each subject and remained constant throughout the two test periods. During the test, peak power (PP), mean power during the first 30 s (MP30 s) and the full 60 s of the test (MP60 s), and fatigue (i.e., the decrease in power output values throughout the exercise) were analyzed. Results confirmed the existence of diurnal variation in anaerobic power output. PP, MP30 s, and MP60 s were significantly higher at 18:00 than 06:00 h, with gains equal to 8.2, 7.8, and 7.8%, respectively. Moreover, all the power output values recorded in the evening were higher than those recorded in the morning, indicating that fatigue induced by this exercise is not affected by time-of-day in male competitive cyclists. It is hypothesized that the freedom and complexity of pedalling could allow adaptations in movement patterns, as a function of time-of-day, in order to maintain higher performance in the evening. For practical considerations, the more complex the movements required to perform a sport, the more the time-of-day effect can be taken into account and adapted to by the trained athlete, particularly in cyclic sporting disciplines such as swimming, running, rowing, and kayaking.
The effect of travel on athletic performance has been investigated in previous studies. The purpose of this study was to investigate this effect on game outcome over 10 Major League Baseball (MLB) seasons.
Using the convention that for every time zone crossed, synchronization requires 1 d, teams were assigned a daily number indicating the number of days away from circadian resynchronization. With these values, wins and losses for all games could be analyzed based on circadian values.
19,079 of the 24,121 games (79.1%) were played between teams at an equal circadian time. The remaining 5,042 games consisted of teams playing at different circadian times. The team with the circadian advantage won 2,620 games (52.0%, P = .005), a winning percentage that exceeded chance but was a smaller effect than home field advantage (53.7%, P < .0001). When teams held a 1-h circadian advantage, winning percentage was 51.7% (1,903-1,781). Winning percentage with a 2-h advantage was 51.8% (620-578) but increased to 60.6% (97-63) with a 3-h advantage (3-h advantage > 2-hadvantage = 1-h advantage, P = .036). Direction of advantage showed teams traveling from Western time zones to Eastern time zones were more likely to win (winning percentage = .530) than teams traveling from Eastern time zones to Western time zones (winning percentage = .509) with a winning odds 1.14 (P = .027).
These results suggest that in the same way home field advantage influences likelihood of success, so too does the magnitude and direction of circadian advantage. Teams with greater circadian advantage were more likely to win.
The aim was to test the hypothesis that one night of sleep deprivation will impair pre-loaded 30 min endurance performance and alter the cardio-respiratory, thermoregulatory and perceptual responses to exercise. Eleven males completed two randomised trials separated by 7 days: once after normal sleep (496 (18) min: CON) and once following 30 h without sleep (SDEP). After 30 h participants performed a 30 min pre-load at 60% followed by a 30 min self-paced treadmill distance test. Speed, RPE, core temperature (T
re), mean skin temperature (T
sk), heart rate (HR) and respiratory parameters (, , , RER pre-load only) were measured. Less distance (P = 0.016, d = 0.23) was covered in the distance test after SDEP (6037 (759) 95%CI 5527 to 6547 m) compared with CON (6224 (818) 95%CI 5674 to 6773 m). SDEP did not significantly alter T
re at rest or thermoregulatory responses during the pre-load including heat storage (0.8°C) and T
sk. With the exception of raised at 30 min on the pre-load, cardio-respiratory parameters, RPE and speed were not different between trials during the pre-load or distance test (distance test mean HR, CON 174 (12), SDEP 170 (13) beats min−1: mean RPE, CON 14.8 (2.7), SDEP 14.9 (2.6)). In conclusion, one night of sleep deprivation decreased endurance performance with limited effect on pacing, cardio-respiratory or thermoregulatory function. Despite running less distance after sleep deprivation compared with control, participants’ perception of effort was similar indicating that altered perception of effort may account for decreased endurance performance after a night without sleep.
The ability to generate torque during a maximum voluntary contraction (MVC) changes over the day. The present experiments were designed to determine the influence of an individual's chronotype on this diurnal rhythm and on cortical, spinal, and peripheral mechanisms that may be related to torque production. After completing a questionnaire to determine chronotype, 18 subjects (9 morning people, 9 evening people) participated in 4 data collection sessions (at 09:00, 13:00, 17:00, and 21:00) over 1 day. We used magnetic stimulation of the cortex, electrical stimulation of the tibial nerve, electromyographic (EMG) recordings of muscle activity, and isometric torque measurements to evaluate the excitability of the motor cortex, the spinal cord, and the torque-generating capacity of the triceps surae (TS) muscles. We found that for morning people, cortical excitability was highest at 09:00, spinal excitability was highest at 21:00, and there were no significant differences in TS EMG or torque produced during MVCs over the day. In contrast, evening people showed parallel increases in cortical and spinal excitability over the day, and these were associated with increased TS EMG and MVC torque. There were no differences at the level of the muscle over the day between morning and evening people. We propose that the simultaneous increases in cortical and spinal excitability increased central nervous system drive to the muscles of evening people, thus increasing torque production over the day. These differences in cortical excitability and performance of a motor task between morning and evening people have implications for maximizing human performance and highlight the influence of chronotype on an individual's diurnal rhythms.
Fast swim times in morning rounds are essential to ensure qualification in evening finals. A significant time-of-day effect in swimming performance has consistently been observed, although physical activity early in the day has been postulated to reduce this effect. The aim of this study was to compare intradaily variation in race-pace performance of swimmers routinely undertaking morning and evening training (MEG) with those routinely undertaking evening training only (EOG).
Each group consisted of 8 swimmers (mean +/- SD: age = 15.2 +/- 1.0 and 15.4 +/- 1.4 y, 200-m freestyle time 132.8 +/- 8.4 and 136.3 +/- 9.1 s) who completed morning and evening trials in a randomized order with 48 h in between on 2 separate occasions. Oral temperature, heart rate, and blood lactate were assessed at rest, after a warm-up, after a 150-m race-pace swim, and after a 100-m time trial. Stroke rate, stroke count, and time were recorded for each length of the 150-m and 100-m swims.
Both training groups recorded significantly slower morning 100-m performances (MEG = +1.7 s, EOG = +1.4 s; P < .05) along with persistently lower morning temperatures that on average were -0.47 degrees C and -0.60 degrees C, respectively (P < .05). No differences were found in blood-lactate, heart-rate, and stroke-count responses (P > .05). All results were found to be reproducible (P > .05).
The long-term use of morning training does not appear to significantly reduce intradaily variation in race-pace swimming or body temperature.
The purpose of this study was to determine whether delaying bedtime or advancing rising time by 4 h affects anaerobic performance of individuals the following day in the morning and afternoon. Eleven subjects participated in the study, during which we measured the maximal, peak, and mean powers (i.e., P(max) [force-velocity test], P(peak), and P(mean) [Wingate test], respectively). Measurements were performed twice daily, at 07:00 and 18:00 h, following a reference normal sleep night (RN), a partial sleep deprivation timed at the beginning of the night (SDB), and a partial sleep deprivation timed at the end of the night (SDE), and oral temperature was measured every 4 h. Each of the three experimental conditions was separated by a one-week period. Our results showed a circadian rhythm in oral temperature, and analysis of variance revealed a significant sleep x test-time effect on peak power (P(peak)), mean power (P(mean)), and maximal power (P(max)). These variables improved significantly from the morning to the afternoon for all three experimental conditions. Whereas the morning-afternoon improvement in the measures was similar after the RN and SDB conditions, it was smaller following the SDE condition. There was no significant difference in the effect of the two sleep-deprivation conditions on anaerobic performances at 07:00 and at 18:00 h under the SDB condition in comparison with the post-reference night. However, the performance variables were significantly lower at 18:00 h after the SDE condition. In conclusion, a 4 h partial sleep deprivation at the end of the night appears to be more disturbing than partial sleep deprivation at the beginning of the night.
The effects of circadian rhythms on human performance in general and on response to exercise in particular are a well-known phenomenon. Often after a poor night's sleep or taking a "red-eye" flight into a different time-zone, one just doesn't feel like "themselves." This book aims to provide a comprehensive account of biological rhythms and how they affect exercise. Particular attention is given to sleep, its biological function, and the consequences for exercise performance of sleep loss. There are chapters devoted to the effects of disturbing the circadian body clock, such as when multiple time zones are crossed and jet-lag experienced. The effects of nocturnal shift work and seasonal variation are also covered. The interactions between exercise and the female menstrual cycle are explained and the issue of exercise during pregnancy discussed. Finally, there is a chapter devoted to research methods in chronobiology, the scientific discipline underpinning the content of the book.
This study was conducted to describe the time-of-day effect on muscle fatigue during both intermittent concentric (CE) and eccentric (EE) exercises. A second aim was to examine whether the time of day at which the exercise was performed influenced recovery of muscle strength. Ten male subjects performed CE and EE consisting of 5 sets of 10 maximal voluntary contractions (MVC) of the elbow flexors (angular velocity: 60°/s) at two different times (06:00 h and 18:00 h). Torque and Electromyographic activities (EMG) of the biceps brachii and triceps brachii were recorded before (Pre), during and immediately after (Post) each fatiguing task. Furthermore, strength recovery was measured 2 days (Post_{2d}), 3 days (Post_{3d}) and 7 days (Post_{7d}) after each fatiguing task. Results showed that during CE, torque variations were greater at 18:00 h than at 06:00 h. No time-of-day effect occurred during EE. Recovery time was faster in the morning than in the evening for isometric MVC only. To conclude, unlike the case in eccentric mode, mechanisms involved in concentric muscle action appear to be time-of-day dependent, with a greater muscle capacity in the late afternoon. Also, strength recovery is greater when fatiguing exercises are performed in the early morning than in the late afternoon.
Partial sleep loss comprises a common source of potential stress. The effects of a nightly ration of 2.5 hr sleep on a battery of psychomotor, physical working capacity and subjective state tests were investigated in a group of trained subjects (n=8) over 3 nights of sleep loss and a single night of subsequent recovery sleep. A 3-day period where normal sleep was permitted was used as a control, the order of control and experimental presentation being counterbalanced. A significant treatment effect was observed for anxiety, hand steadiness, choice reaction time (CRT) preexercise and anaerobic power while grip strength, lung function and endurance capacity were unaffected. Exercise was found to attenuate the effects of sleep loss on CRT. A significant trend over days was found for hand steadiness and reciprocal tapping. All measures except hand steadiness had returned to baseline levels after the recovery night's sleep. It was concluded that one night's sleep of only 2.5 hr has a detrimental effect on psychomotor function but that gross motor functions remain intact for up to 3 nights of partial sleep deprivation.
Twenty-six healthy, untrained men (23.3 +/- 4.4 years) were determined to be morning, intermediate or evening chronotypes using the 1976 Horne and Ostberg questionnaire. Each individual underwent a series of two maximal treadmill tests (Bruce protocol) at two different times of day: 7:30-8:30 a.m. (morning or M test), and 7:30-8:30 p.m (evening or E test). The M and E tests were administered a minimum of 48 hours apart using a randomized counter-balanced design. Heart rate, ventilation, oxygen consumption, carbon dioxide production, respiratory exchange ratio, rating of perceived exertion and total exercise time were monitored at each test session. Subject grouping, according to the questionnaire, revealed an age-related difference, with a higher mean age for the morning types compared to intermediate (t = 3.27, p < 0.01) or evening (t = 2.44, p < 0.05) types. Multivariate analysis of variance did not reveal significant differences in maximum exercise performance according to chronotype. Heart rate (F = 4.41, p < 0.05) and performance time (F = 5.13, p < 0.03) increased during the E test. While performance differences during maximum exercise were not detected between chronotypes, further study with submaximal exercise intensity and variable duration should be conducted.
Time-dependent changes in elbow flexion torque have been documented according to two different sampling schedules. Seven physical education students took part in the first series of experiments, and 7 other similar subjects in the second. In both sets of experiments, the subjects performed isometric contractions: maximal and submaximal at 90° in the first experiments and maximal at different angular positions in the second. After a 30-minute rest period, the torque developed was measured at 00:00, 06:00, 09:00, 12:00, 15:00, 18:00, and 21:00h on the day of the experiment. These subjects remained in the laboratory for 24h. In the second series of experiments, the torque developed was measured at 01:00, 05:00, 09:00, 13:00, 17:00, and 21:00h over the subsequent 6 days with only one test session per day. In this case, there was an interval of 20h between two successive test sessions. In the first experiment, a significant time-of-day effect was observed for the torque of the elbow flexors under isometric conditions with an acrophase at 17:58h. The 24h normalized mean score was 92.85% with an amplitude of 7.63% of the daily mean. In the second series of experiments, there was evidence of a circadian rhythm in the torque developed by the elbow flexors at every angle position, especially at 90°, the angle investigated in the first set of experiments. The peak torque was calculated to have occurred at 17:55h. The amplitude of the rhythm was equal to 6.99% of the daily mean. There were no statistically significant differences in the characteristics of the circadian rhythm observed between the two experimental designs. We concluded that an experiment extending over several days could be employed to evaluate circadian rhythms in muscular activity reliably. (Chronobiology International, 14(3), 287–294, 1997)
The aim of this study was to observe how the combined effects of time-of-day and sleep deprivation impact motocross riders’ physical abilities. Balance, flexibility and maximal anaerobic alactic power were tested across laboratory tests that required only one ability (stork stand test, sit-and-reach test, Abalakov test) or across field tests that concentrated on a particular ability (narrow board riding test, riding under a rod test, long jump riding test) to maximise the sensitivity of the assessments and the interpretability of findings. Eight motocross riders of confirmed level took part in test sessions set up at 0600 and 1800 hours following a normal night’s sleep and a night of sleep deprivation, i.e. after 1, 13, 23 and 35 waking hours. On the one hand, the results confirmed the influence of time-of-day on riders’ physical abilities, performances being better at 1800 hours than at 0600 hours after the normal night’s sleep. On the other hand, as far as sleep deprivation effects are concerned, the results seemed to differ on the basis of the ability under consideration and the type of test that had been set up. Performance in the field tests still presented a diurnal fluctuation, whereas this improvement over the day did not occur for the performance in the laboratory tests. It seems that compensation mechanisms between the various abilities brought into play are set up in order to moderate the effects of the lack of sleep when riding.
While in the 1st part of the author's review (see record
1978-11474-001) the problem of arousal and arousal changes after sleep deprivation were discussed, the 2nd part (see record
1978-11605-001) dealt with lapses and other attentional effects. The present part reviews the problems of motivation and performance in connection with sleep deprivation. All 3 parts of the review are commented on, and conclusions are drawn from the complete material. References for all 3 parts are given. (76 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Discusses 3 papers by the author (see also PA, Vol 59:11595 and 11605) that attempt to provide a theoretical framework within which the performance effects of sleep deprivation (SD) can be interpreted. Primarily, the possibilities and limitation of interpretations in terms of de-arousal are evaluated. An interactional view of the relation between SD and arousal is proposed, implying that the effect of SD is to potentiate the de-arousing effect of situational variables. The habituation of the orienting response is suggested as one possible mediator of this effect. The reported attentional effects of SD are shown to be interpretable within this framework. The effects of motivational factors on the SD effects and the SD effect on motivation are discussed, leading to the conclusion that habituation cannot be the only mediator of the de-arousing influence of the situation and that an analysis in operant terms must be added. Furthermore, the motivational effects of SD demonstrate the limitations of the present arousal analysis of the effects. Implications for SD research are discussed. References are given with Part III of this review. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Previous studies have suggested a diurnal variation in the performance of physical tasks. The theoretical basis for the effect of time-of-day on performance centers on the circadian rhythms of many physiological variables and especially the body temperature curve. This investigation had two purposes: (a) to determine if increasing the volume of the warm-up could eliminate diurnal variation in body temperature and swim performance, and (b) to determine if reduction of the warm-up volume in the late afternoon would affect body temperature and swim performance. Participants for this investigation included 6 male and 4 female competitive swimmers (mean age = 15 +/- 1 years). Before the swim performance trials in the morning, participants warmed up with either standard volume (2,011.68 m) or 200 0 of that volume. Before the afternoon swim performance trials, warm-up volumes were either 33% or 100% of the standard warm-up volume. Before entering the water and immediately after the warm-up, temperature was taken from the ear. After the swim performance, participants were asked to rate their perceived exertion on the basis of Borg's CR-10 rating scale. The order of test administration for time of day and warm-up condition was balanced and with tests carried out over 4 days. Each swimmer completed 1 test condition (warm-up) per day. Results indicated that increased morning warm-up time eliminated diurnal variation in body temperature; however, evening superiority in swimming performance was not eliminated. The results also indicated that reducing the volume of the afternoon warm-up to 33% of the standard warm-up had no effect on body temperature or swim performance.
The after-effects of night work on physical performance capacity and sleep quality were studied. Ten younger (age 34 years) and eight older (age > 34 years) experienced shift workers were examined. Subjects performed cycle ergometer tests at an exercise intensity requiring 70% of the individual maximal oxygen uptake. Two conditions were studied: a baseline condition, i.e. the last day of a 4 days-off period, and a recovery condition after a period of seven consecutive night shifts, i.e. the second day-off after the night-shift period (32 h after leaving the night-shift period). Sleep quality of the sleep period preceding the test was also measured for both conditions. During the recovery condition the endurance time (i.e. time to exhaustion) was reduced by an average of 20% (–160s, P < 0.05)="" for="" the="" older="" shift="" workers="" only.="" in="" both="" age="" groups="" exercise="" ventilation,="" heart="" rate,="" oxygen="" uptake,="" perceived="" exertion="" and="" sleep="" quality="" remained="" unaffected.="" these="" findings="" support="" the="" hypothesis="" that="" the="" aging="" shift="" worker="" is="" faced="" with="" increasing="" complaints,="" even="" after="" the="" night-shift="" period.="" however,="" to="" clarify="" the="" mechanisms="" responsible="" for="" these="" after-effects="" of="" night="" work,="" further="" extensive="" studies="" must="" be="">
The number of travellers undertaking long-distance flights has continued to increase. Such flights are associated with travel fatigue and jet lag, the symptoms of which are considered here, along with their similarities, differences, and causes. Difficulties with jet lag because of sleep loss and decreased performance are emphasised. Since jet lag is caused mainly by inappropriate timing of the body clock in the new time zone, the pertinent properties of the body clock are outlined, with a description of how the body clock can be adjusted. The methods, both pharmacological and behavioural, that have been used to alleviate the negative results of time-zone transitions, are reviewed. The results form the rationale for advice to travellers flying in different directions and crossing several time zones. Finally, there is an account of the main problems that remain unresolved.
Previous studies investigating the impact of circadian rhythms on physiological variables during exercise have yielded conflicting results. The purpose of the present investigation was to examine maximal aerobic exercise performance, as well as the physiological and psychophysiological responses to exercise, at four different intervals (0800 hours, 1200 hours, 1600 hours, and 2000 hours) within the segment of the 24-h day in which strenuous physical activity is typically performed. Ten physically fit, but untrained, male university students served as subjects. The results revealed that exercise performance was unaffected by chronobiological effects. Similarly, oxygen uptake, minute ventilation and heart rate showed no time of day influences under pre-, submaximal, and maximal exercise conditions. Ratings of perceived exertion were unaffected by time of day effects during submaximal and maximal exercise. In contrast, rectal temperature exhibited a significant chronobiological rhythm under all three conditions. Under pre- and submaximal exercise conditions, significant time of day effects were noted for respiratory exchange ratio, while a significant rhythmicity of blood pressure was evident during maximal exercise. However, none of these physiological variables exhibited significant differential responses (percent change from pre-exercise values) to the exercise stimulus at any of the four time points selected for study. Conversely, resting plasma lactate levels and lactate responses to maximal exercise were found to be significantly sensitive to chronobiological influences. Absolute post-exercise plasma norepinephrine values, and norepinephrine responses to exercise (percent change from pre-exercise values), also fluctuated significantly among the time points studied. In summary, these data suggest that aerobic exercise performance does not vary during the time frame within which exercise is normally conducted, despite the fact that some important physiological responses to exercise do fluctuate within that time period.
The purpose was to test the hypothesis that time to exhaustion and oxygen deficit in high-intensity exercise at a particular time of day would be influenced by training regularly at that time of day.
Over a 5-wk period, 12 college-age women performed 20 high-intensity exercise training sessions. On Mondays, they performed four 2-min bouts of cycling at 2.5 W x kg(-1) with 4-min recoveries; on Tuesdays and Thursdays, eight 1-min bouts at 3.0 W x kg(-1) with 2-min recoveries; and on Wednesdays, three 3-min bouts at 2.2 W x kg(-1) with 2-min recoveries. Six participants (a.m.-trained group) were randomly assigned to train in the morning (a.m.) and six others (p.m.-trained group) trained in the afternoon (p.m.). Upon completion of training, all participants were tested in both the a.m. and p.m. (random order) at the same times as training sessions had been scheduled. Tests involved exhaustive efforts at 2.6 W x kg(-1).
Results of a repeated measures ANOVA revealed a significant time of day of training x time of day of testing interaction effect on time to exhaustion (F1,10=8.29, P=0.02). This suggested that the time of day of training affected the a.m.-p.m. pattern in time to exhaustion. Time to exhaustion for the a.m.-trained group was 398+/-258 s in the a.m. test and 351+/-216 s in the p.m. test (P=0.07). The p.m.-trained group had significantly higher values in the p.m. test compared with the a.m. test (422+/-252 s vs 373+/-222 s; P=0.03). There was also a significant interaction effect on oxygen deficit (F1,10=8.03, P=0.02). This suggested that the time of day of training affected the a.m.-p.m. pattern in anaerobic capacity. Oxygen deficit for the a.m.-trained group was 64+/-24 mL x kg(-1) in the a.m. test and 50+/-11 mL x kg(-1) in the p.m. test (P=0.10). The p.m.-trained group had significantly higher values in the p.m. tests (64+/-24 mL x kg(-1) vs 50+/-11 mL x kg(-1); P=0.01) compared to the a.m. tests.
These results demonstrate that there is temporal specificity in training to increase work capacity in high-intensity exercise. Greater improvements can be expected to occur at the time of day at which high-intensity training is regularly performed.
The study investigated the effects of circadian rhythm of cortisol (C) and testosterone (T) on maximal force production (Fpeak) and power output (Ppeak). Twenty male university students (mean age = 23.8 ± 3.6 years, height = 177.5 ± 6.4 cm, weight = 78.9 ± 11.2 kg) performed 4 time-of-day testing sessions consisting of countermovement jumps (CMJs), squat jumps (SJ), isometric midthigh pulls (IMTPs), and a 1-repetition maximum (1RM) squat. Saliva samples were collected at 0800, 1200, 1600, and 2000 hours to assess T and C levels on each testing day. Session rate-of-perceived exertion (RPE) scores were collected after each session. The results showed that Fpeak and Ppeak presented a clear circadian rhythm in CMJ and IMTP but not in SJ. One repetition maximum squat did not display a clear circadian rhythm. Session RPE scores collected at 0800 and 2000 hours were significantly (p ≤ 0.05) higher than those obtained at 1200 and 1600 hours. Salivary T and C displayed a clear circadian rhythm with highest values at 0800 hours and lowest at 2000 hours; however, no significant correlation was found between T and C with Fpeak and Ppeak. A very strong correlation was found between Taural with Fpeak of CMJ and IMTP and Ppeak of CMJ (r = 0.86, r = 0.84 and r = 0.8, p ≤ 0.001). The study showed the existence of a circadian rhythm in Fpeak and Ppeak in CMJ and IMTP. The evidence suggests that strength and power training or testing should be scheduled later during the day. The use of Taural seemed to be a more effective indicator of physical performance than hormonal measures, and the use of session RPE should also be closely monitored because it may present a circadian rhythm.
The purpose of this study was to investigate whether maximal muscle power production in humans is influenced by the habitual time of training to provide recommendations for adapting training hours in the month preceding a competition. Sixteen participants performed maximal brief squat and countermovement jumps and short-term cycle sprints tests before and after 5 weeks of training. Subjects were randomly assigned to either a Morning-Trained Group (MTG, 7:00-9:00 hr) or an Evening-Trained Group (ETG, 17:00-19:00 hr). They trained and performed the evaluation tests in both the morning and evening in their naturally warm and moderately humid environment. The results indicated a significant increase in performance (approximately 5-6% for both tests) after training for both groups but failed to show any time-of-day effect on either performance or training benefit. These findings could be linked to the stabilization of performances throughout the day because of the passive warm-up effect of the environment. In summary, our data showed that anaerobic muscle power production could be performed at any time of day with the same benefit.
This study investigated the effect of time of day on endurance exercise capacity in a warm environment.
Nine males cycled to exhaustion at 65% .VO2peak in an ambient temperature of 35 degrees C (60% relative humidity) at 0645 h (AM) and 1845 h (PM). Rectal temperature (Tc), skin temperature (Tsk), and heart rate (HR) were recorded and blood and expired air samples collected at rest every 5 min during exercise and during recovery.
Time to exhaustion was longer in the AM trial (45.8 +/- 10.7 min) than in the PM trial (40.5 +/- 9.0 min; P = 0.009). Resting Tc was lower in the AM trial and remained lower for the first 25 min of exercise (P < 0.001). Tc was not different between trials at the point of exhaustion (AM = 38.7 +/- 0.9 degrees C, PM = 38.8 +/- 0.6 degrees C; P = 0.847). Tsk followed a similar pattern, being lower at rest (P = 0.003) and during the initial stages of exercise (P < 0.05) in the AM trial but not different at exhaustion (P = 0.896). The rate of rise of Tc tended to be greater in the AM trial (P = 0.052), and the rate of rise of Tsk (P = 0.032) and of body heat content (P = 0.009) was also greater in the AM trial. HR was initially higher in the PM trial, but there was no difference at exhaustion. There were no differences between trials in blood glucose concentration or plasma volume change.
The results of this study suggest that endurance exercise capacity in the heat was significantly greater in the morning than the evening, possibly due to a lower initial Tc.
During adolescence and early adulthood, most humans are predisposed developmentally, both biologically and socially, toward evening/night activity. The morningness-eveningness (M-E) tendency to be an evening-preferring (E-type) rather than a morning-preferring (M-type) or intermediate/neither (N-type) "chronotype" may affect athletic performance at various times of day. This study evaluated M-E effects on rowing performance of an intact, experienced, university club crew with near-daily early morning (0500-0700 hours) and late afternoon (1630-1800 hours) training schedules. The hypothesis tested was that chronotype would modify circadian effects during morning and afternoon performances. Eight men and eight women (mean age 19.6 +/- 1.5 years) were tested in a randomized, counterbalanced design. A standard qualifying 2000-m ergometer rowing sprint and a nonroutine standing broad jump task were measured during early morning and late afternoon, separated by 3 days of rest. Each subject's chronotype was determined using two standard self-rating M-E scales, resulting in eight E-type (three women/five men), four M-type (two women/two men), and four N-type (three women/one man) subjects. The rowing results show that E-type and N-type subjects did not differ between morning and afternoon rowing performances, whereas M-type subjects rowed significantly faster in the morning. In contrast, the standing broad jump showed no consistent time-of-day or chronotype effect. These findings suggest that basic performance timing in young athletes is determined to some extent by naturally occurring M-E predispositions. Further, modification of time-of-day influences may be possible by routine practice at the same time each day, as was suggested here by the absence of evening superiority in performances. Understanding their personal M-E tendencies could allow young athletes to arrange training schedules at specific times of day to help counteract any natural circadian influences that might work against their performance.
Circadian rhythm sleep disorders are common in clinical practice. The disorders covered in this review are delayed sleep phase disorder, advanced sleep phase disorder, free-running, irregular sleep-wake rhythm, jet lag disorder and shift work disorder. Bright light treatment and exogenous melatonin administration are considered to be the treatments of choice for these circadian rhythm sleep disorders. Circadian phase needs to be estimated in order to time the treatments appropriately. Inappropriately timed bright light and melatonin will likely worsen the condition. Measurements of core body temperature or endogenous melatonin rhythms will objectively assess circadian phase; however, such measurements are seldom or never used in a busy clinical practice. This review will focus on how to estimate circadian phase based on a careful patient history. Based on such estimations of circadian phase, we will recommend appropriate timing of bright light and/or melatonin in the different circadian rhythm sleep disorders. We hope this practical approach and simple recommendations will stimulate clinicians to treat patients with circadian rhythm sleep disorders.
Previous work has demonstrated that exercise performance varies with time of day. The aim of this study was to investigate the influence of time of day on measures of anaerobic power and anaerobic capacity. Twelve male subjects, aged 18-22 years, performed a stair run test, a standing broad jump and the Wingate Anaerobic Test on twelve separate occasions. These were at 02:00, 06:00, 10:00, 14:00, 18:00 and 22:00 hours, duplicate measurements being obtained at each time point. Subjects' diet and activity prior to exercise and the laboratory temperature were controlled. Pre-exercise rectal temperature was measured on each occasion. The rectal temperature data conformed to a cosine function: its peak occurred at 18:11 hours and the peak to trough variation was 0.76 degrees C (p < 0.001). There was a rhythm in performance on the stair run and the broad jump tests, in phase with the curve in rectal temperature. Results for peak power and mean power production on the Wingate test did not display a significant circadian rhythm. The stair run and broad jump tests seem to be more sensitive to circadian rhythmicity than does the Wingate Anaerobic Test.