Effects of two nights of sleep deprivation on executive function and central and peripheral fatigue during maximal voluntary contraction lasting 60s.

PURPOSEː: The current study aimed at assessing the effect of a trial of two nights of sleep deprivation (SDT) on mood, sleepiness, motivation and cognitive and motor performance. METHODSː: Thirty-six healthy young and physically active adult men (17 in the control group and 19 in the SDT group) completed a 48-h control or 48-h SDT. For the SDT, participants did not sleep for 48 h. Executive function (attention and inhibitory control) in the Go/No-Go and Stroop tests, mood, sleepiness, motivation, heart rate variability (HRV), motor performance in a hand grip strength test, and 60-s maximal isometric contraction (MVC-60 s) of knee extension were evaluated at 9-11 am on consecutive days 1, 2, and 3. RESULTS: One night of sleep deprivation increased sleepiness, decreased mood, motivation and motor endurance but did not affect executive function (as measured in the Stroop and Go/No-Go tests), the MVC for hand and leg knee extensor muscles, and peripheral motor fatigue in the leg MVC-60 s task. However, the central activation ratio (CAR) decreased significantly during the MVC-60 s. The SDT significantly contributed to the decrease in these functions. That is, the SDT reduced executive function (increased reaction time during Go/No-Go test), MVC of knee extension, and the CAR before and after the MVC-60 s. By contrast, the SDT did not increase CAR immediately after the MVC-60 s and did not decrease the rate of torque development (RTD). CONCLUSIONSː: The SDT significantly impaired mood, motivation and increased sleepiness and HRV, reduced MVC of knee extensor muscles (but not RTD) and motor performance during the MVC-60 s and worsened executive function (attention and inhibitory control) only during the Go/No-Go task. However, the SDT did not reduce hand grip strength and CAR immediately after the MVC-60 s of knee extensor muscles.

Body Composition in International Sprint Swimmers: Are There Any Relations with Performance?

The paper addresses relations between the characteristics of body composition in international sprint swimmers and sprint performance. The research included 82 swimmers of international level (N = 46 male and N = 36 female athletes) from 8 countries. We measured body composition using multifrequency bioelectrical impedance methods with "InBody 720" device. In the case of male swimmers, it was established that the most important statistically significant correlation with sprint performance is seen in variables, which define the quantitative relationship between their fat and muscle with the contractile potential of the body (Protein-Fat Index, r = 0.392, p = 0.007; Index of Body Composition, r = 0.392, p = 0.007; Percent of Skeletal Muscle Mass, r = 0.392, p = 0.016). In the case of female athletes, statistically significant relations with sprint performance were established for variables that define the absolute and relative amount of a contractile component in the body, but also with the variables that define the structure of body fat characteristics (Percent of Skeletal Muscle Mass, r = 0.732, p = 0.000; Free Fat Mass, r = 0.702, p = 0.000; Fat Mass Index, r = -0.642, p = 0.000; Percent of Body Fat, r = -0.621, p = 0.000). Using Multiple Regression Analysis, we managed to predict swimming performance of sprint swimmers with the help of body composition variables, where the models defined explained 35.1 and 75.1% of the mutual variability of performance, for male and female swimmers, respectively. This data clearly demonstrate the importance of body composition control in sprint swimmers as a valuable method for monitoring the efficiency of body adaptation to training process in order to optimize competitive performance.

The Influence of an Enriched Sport Program on Children's Sport Motivation in the School Context: The ESA PROGRAM.

PURPOSE: Besides the evident positive effect on body development, physical activity has proven to boost executive functions, especially if the exercises are enriched with cognitive stimuli. Previous studies have shown that introducing challenging exercises in the physical activity routine can also enhance motivation. Therefore, enriching a physical education program with cognitively challenging exercises may also foster children's motivation during physical education classes, where the motivation is high at the beginning of the school year and low at the end of it. Therefore, the purpose of this paper is to test if a sport program enriched by cognitive stimuli may improve kids' motivation or take them out from a state of amotivation along the school year. METHODS: A sample of 342 school children (203 boys, 139 girls) took part in the study. Participants were asked to complete a battery of motivation and perceived social support questionnaires before and after they completed the ESA Program, a sport program enriched with cognitive stimuli. Moreover, parents of these children attended four seminars about the importance of supporting children for the practice of regular physical activity (PA). A control group consisting of children that attended the ordinary physical education school class was also included. RESULTS: A repeated measures MANOVA model showed that the ESA Program was able to improve children's general motivation, in particular the intrinsic motivation. The program was not effective in social support, but, independently from the group, the family social support in sports activities decreased for females. CONCLUSION: Apart from cognitive improvement, the ESA Program can have beneficial effects on children's sports motivation in physical education, but not on perceived social support.

Daily Resting Heart Rate Variability in Adolescent Swimmers during 11 Weeks of Training.

Adolescent athletes are particularly vulnerable to stress. The current study aimed to monitor one of the most popular and accessible stress markers, heart rate variability (HRV), and its associations with training load and sleep duration in young swimmers during an 11-week training period to evaluate its relevance as a tool for monitoring overtraining. National-level swimmers (n = 22, age 14.3 ± 1.0 years) of sprint and middle distance events followed individually structured training programs prescribed by their swimming coach with the main intention of preparing for the national championships. HRV after awakening, during sleep and training were recorded daily. There was a consistent ~4.5% reduction in HRV after 3-5 consecutive days of high (>6 km/day) swimming volume, and an inverse relationship of HRV with large (>7.0 km/day) shifts in total training load (r = -0.35, p < 0.05). Day-to-day HRV did not significantly correlate with training volume or sleep duration. Taken together, these findings suggest that the value of HRV fluctuations in estimating the balance between the magnitude of a young athlete's physical load and their tolerance is limited on a day-to-day basis, while under sharply increased or extended training load the lower HRV becomes an important indicator of potential overtraining.

Effects of a Physical Activity Intervention on Physical Fitness of schoolchildren: The Enriched Sport Activity Program.

Background: Physical fitness in youth is a predictor of health in adulthood. The main objective of the present study was to understand if an enriched sport activity program could increase physical fitness in a population of schoolchildren. Methods: In a sample of 672 children aged 10.0 ± 1.90 years, different motor skills were tested by the 1 kg and 3 kg ball throw (BT), the standing broad jump (SBJ), the 30 m sprint (30mS), the leger shuttle run (LSR), the illinois agility test (IGT), and the quadruped test (QT). Within the controlled-trial, the intervention group (ESA) underwent an additional warm-up protocol, which included cognitive enhancing elements, for 14 weeks while the control group continued with ordinary exercise activity. Results: A significant increase was present regarding the 1 kg and 3 kg BT, the SBJ, the 30mS, and the IGT, while no significant difference was shown regarding the QT and the LSR in the ESA group between pre and post intervention. In the control group, no differences were present for any test except for the QT and the LSR post-test. Conclusion: A 14-week structured physical intervention had moderate effects regarding throwing, jumping, sprinting, and agility in a sample of schoolchildren.