Murilo Dáttilo

Sleep and muscle recovery: Endocrinological and molecular basis for a new and promising hypothesis

Sleep is essential for the cellular, organic and systemic functions of an organism, with its absence being potentially harmful to health and changing feeding behavior, glucose regulation, blood pressure, cognitive processes and some hormonal axes. Among the hormonal changes, there is an increase in cortisol (humans) and corticosterone (rats) secretion, and a reduction in testosterone and Insulin-like Growth Factor 1, favoring the establishment of a highly proteolytic environment. Consequently, we hypothesized that sleep debt decreases the activity of protein synthesis pathways and increases the activity of degradation pathways, favoring the loss of muscle mass and thus hindering muscle recovery after damage induced by exercise, injuries and certain conditions associated with muscle atrophy, such as sarcopenia and cachexia.

The influence of sleep and sleep loss upon food intake and metabolism

The present review investigates the role of sleep and its alteration in triggering metabolic disorders. The reduction of the amount of time sleeping has become an endemic condition in modern society and the current literature has found important associations between sleep loss and alterations in nutritional and metabolic aspects. Studies suggest that individuals who sleep less have a higher probability of becoming obese. It can be related to the increase of ghrelin and decrease of leptin levels, generating an increase of appetite and hunger. Sleep loss has been closely associated with problems in glucose metabolism and a higher risk for the development of insulin resistance and diabetes, and this disturbance may reflect decreased efficacy of the negative-feedback regulation of the hypothalamic-pituitary-adrenal axis. The period of sleep is also associated with an increase of blood lipid concentrations, which can be intensified under conditions of reduced sleep time, leading to disorders in fat metabolism. Based on a review of the literature, we conclude that sleep loss represents an important risk factor for weight gain, insulin resistance, type 2 diabetes and dyslipidaemia. Therefore, an adequate sleep pattern is fundamental for the nutritional balance of the body and should be encouraged by professionals in the area.

Relação entre sono e obesidade: uma revisão da literatura

ABSTRACT Relation Between Sleep and Obesity: A Literature Review.Reduction in sleep time has become an endemic condition in modern soci-ety and current literature has found important epidemiological associa-tions between damage in the habitual standard of sleep and obesity. Onthis basis, the present revision analyzed the role of sleep and its alterationin the promotion of obesity. Diverse studies indicate that subjects thatsleep less have greater possibility of becoming obese, and the shorteningof sleep increases the leptin/grelin reason, generating increase of theappetite and hunger. This can be associated to the biggest caloric intakeand promotion of obesity. An adequate standard of sleep becomes basicfor the regulation of body mass and must be stimulated by health profes-sionals. (Arq Bras Endocrinol Metab 2007;51/7:1041-1049)Keywords: Obesity; Sleep; Leptin; Ghrelin; Food intake O SISTEMA FISIOLOGICO QUE REGULA a massa corporal envolve tantocomponentes centrais como perifericos, os quais interagem com osaspectos ambientais, como a disponibilidade e a composicao da dieta e oexercicio fisico, influenciando, assim, a massa corporal. Embora a geneticadesempenhe um papel importante na determinacao da massa corporal, aaumentada prevalencia da obesidade nas ultimas decadas tem sido forte-mente relacionada com as mudancas no ambiente em que se vive. Ana-lisando as variaveis ambientais que sao provavelmente responsaveis pela“epidemia de obesidade”, a maior parte da atencao esta voltada para o es-tado, custo e composicao do alimento ingerido, e para a capacidade deanular o esforco fisico. No entanto, e possivel que outras variaveis am-

Paradoxical sleep deprivation induces muscle atrophy

Introduction: Because paradoxical sleep deprivation (PSD) induces a catabolic hormone profile, we sought to evaluate the morphology of the tibialis anterior (TA) muscle and testosterone and corticosterone levels of paradoxical sleep–deprived rats.Methods: Three study groups of rats were established: the first group was sleep deprived for 96 h; the second group was also sleep deprived for 96 h, but then returned to their home‐cage and allowed to sleep for the next 96 h; and the third group was the control group, with a normal sleep cycle. Results: PSD reduced the weight and fiber cross‐sectional area of the TA muscle. Moreover, PSD enhanced plasma corticosterone and reduced serum testosterone levels. The 96 h of sleep after PSD was sufficient to restore partially the morphology of TA, while hormones returned to basal levels. Conclusion: PSD induces hormonal alterations that may mediate muscle atrophy. Muscle Nerve, 2012

Resistance training minimizes catabolic effects induced by sleep deprivation in rats

Sleep deprivation (SD) can induce muscle atrophy. We aimed to investigate the changes underpinning SD-induced muscle atrophy and the impact of this condition on rats that were previously submitted to resistance training (RT). Adult male Wistar EPM-1 rats were randomly allocated into 1 of 5 groups: control, sham, SD (for 96 h), RT, and RT+SD. The major outcomes of this study were muscle fiber cross-sectional area (CSA), anabolic and catabolic hormone profiles, and the abundance of select proteins involved in muscle protein synthesis and degradation pathways. SD resulted in muscle atrophy; however, when SD was combined with RT, the reduction in muscle fiber CSA was attenuated. The levels of IGF-1 and testosterone were reduced in SD animals, and the RT+SD group had higher levels of these hormones than the SD group. Corticosterone was increased in the SD group compared with the control group, and this increase was minimized in the RT+SD group. The increases in corticosterone concentrations paralleled changes in the abundance of ubiquitinated proteins and the autophagic proteins LC3 and p62/SQSTM1, suggesting that corticosterone may trigger these changes. SD induced weight loss, but this loss was minimized in the RT+SD group. We conclude that SD induced muscle atrophy, probably because of the increased corticosterone and catabolic signal. High-intensity RT performed before SD was beneficial in containing muscle loss induced by SD. It also minimized the catabolic signal and increased synthetic activity, thereby minimizing the bodys weight loss.

Resistance exercise: A non-pharmacological strategy to minimize or reverse sleep deprivation-induced muscle atrophy

Sleep is important for maintenance of skeletal muscle health. Sleep debt can induce muscle atrophy by increasing glucocorticoids and decreasing testosterone, growth hormone and insulin-like growth factor-I. These hormonal alterations result in a highly proteolytic environment characterized by decreased protein synthesis and increased degradation. Given that sleep deprivation is increasingly prevalent in modern society, strategies to minimize or reverse its adverse effects need to be investigated. Resistance exercise has been suggested as an intervention that would benefit the muscle health. The practice of this type of exercise can increase the concentration of testosterone, growth hormone and insulin-like growth factor I and stimulate the protein synthesis through a key signaling molecule, mammalian target of rapamycin. Thus, we hypothesized that resistance exercise is an important non-pharmacological strategy to counteract deleterious effects of sleep debt on skeletal muscle.

Aplicação da escala de conhecimento nutricional em atletas profissionais e amadores de atletismo

An adequate nutrition is necessary to supply the energy demand required by exercise as much for active individuals and for athletes. However, much more than sports performance, the nutrition knowledge is essential for both populations for prevention of illnesses. Many interventions centered in nutritional education have been lead with the intention to increase nutrition knowledge and, consequently, improve nutritional behaviors. The aim of the present study was to evaluate the nutrition knowledge of professional and amateur track and field athletes with application of a scale previously validated in Brazil. The sample was composed by 26 professional and 41 amateur track and field athletes of several modalities in phase of continuous training. The results have shown that professional and amateur track and field athletes generally presented moderate nutritional knowledge, with the latter presenting punctuation significantly higher than the professional group, a fact associated with their higher educational background. In conclusion, professional track and field athletes present lower nutritional knowledge, which can be partly attributed to the fact that they see the nutritional science with performance as main objective. Further applications of this scale in professional and amateur athletes must be carried out in order to assess the nutritional knowledge level of this population.An adequate nutrition is necessary to supply the energy demand required by exercise as much for active individuals and for athletes. However, much more than sports performance, the nutrition knowledge is essential for both populations for prevention of illnesses. Many interventions centered in nutritional education have been lead with the intention to increase nutrition knowledge and, consequently, improve nutritional behaviors. The aim of the present study was to evaluate the nutrition knowledge of professional and amateur track and field athletes with application of a scale previously validated in Brazil. The sample was composed by 26 professional and 41 amateur track and field athletes of several modalities in phase of continuous training. The results have shown that professional and amateur track and field athletes generally presented moderate nutritional knowledge, with the latter presenting punctuation significantly higher than the professional group, a fact associated with their higher educational background. In conclusion, professional track and field athletes present lower nutritional knowledge, which can be partly attributed to the fact that they see the nutritional science with performance as main objective. Further applications of this scale in professional and amateur athletes must be carried out in order to assess the nutritional knowledge level of this population.

Adipokine levels are altered by shiftwork: a preliminary study.

Shiftwork is often associated with metabolic diseases, and in the past few years, several cytokines have been postulated to contribute to various diseases, including insulin resistance. The aim of this study was to compare the concentrations of adiponectin, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in samples of young adult men exposed to a fixed (i) night shift (n = 9), working from 22:00 to 06:00 h; (ii) early morning shift (n = 6), working from 06:00 to 14:00 h; and (iii) day shift (n = 7), working from 08:00 to 17:00 h. The fixed night-shift and early-morning-shift samples were considered collectively as a shiftworker group given their work times. Blood samples were collected during the regular working day at 4-h intervals over the course of 24 h, thus totaling six samples. Morphological and physical activity parameters did not differ between the three groups. Total energy intake was lowest on the early morning shifts (p < .03). Both shiftworker groups ingested a significantly higher percentage of fat (p < .003) and a lower percentage of carbohydrate (p < .0005) than the day group. The early morning group had a lower mean 24-h level of adiponectin than the other two groups (p = .016), and both the early morning and night groups exhibited higher mean 24-h levels of TNF-α than the day group (p = .0001). The 24-h mean levels of IL-6 did not differ significantly between the groups (p = .147). None of the groups exhibited a significant circadian effect on adiponectin (p = .829), TNF-α (p = .779), or IL-6 (p = .979) levels. These results indicate that individuals who are enrolled in shiftwork are susceptible to alterations in the secretion of cytokines that are involved in insulin resistance and cardiovascular disease, both of which are known to affect this population. (Author correspondence: tmello@demello.net.br)

Meal distribution across the day and its relationship with body composition

Evidence has suggested that meal distribution across the day may influence body composition. This study aimed to evaluate the distribution of energy and macronutrient intake in healthy men and women, and to correlate it with body composition. Fifty-two healthy volunteers (24 men), aged 20–45 years old, participated in the study. Food intake was analyzed by a three-day food record and anthropometric measurements included body mass, height, body mass index, body fat percentage, and waist circumference. Positive correlations were found in men between night fat intake and body mass index, body fat percentage and waist circumference and negative correlations were seen between morning energy and macronutrient intake and the same anthropometric variables. These data suggest that fat intake at night is associated with higher values in anthropometric variables while morning food intake can be associated with lower values in anthropometric variables.

Negative Energy Balance Induced by Paradoxical Sleep Deprivation Causes Multicompartmental Changes in Adipose Tissue and Skeletal Muscle

Objective. Describe multicompartmental changes in the fat and various muscle fiber types, as well as the hormonal profile and metabolic rate induced by SD in rats. Methods. Twenty adult male Wistar rats were equally distributed into two groups: experimental group (EG) and control group (CG). The EG was submitted to SD for 96 h. Blood levels of corticosterone (CORT), total testosterone (TESTO), insulin like growth factor-1 (IGF-1), and thyroid hormones (T3 and T4) were used to assess the catabolic environment. Muscle trophism was measured using a cross-sectional area of various muscles (glycolytic, mixed, and oxidative), and lipolysis was inferred by the weight of fat depots from various locations, such as subcutaneous, retroperitoneal, and epididymal. The metabolic rate was measured using oxygen consumption (V˙O2) measurement. Results. SD increased CORT levels and decreased TESTO, IGF-1, and T4. All fat depots were reduced in weight after SD. Glycolytic and mixed muscles showed atrophy, whereas atrophy was not observed in oxidative muscle. Conclusion. Our data suggest that glycolytic muscle fibers are more sensitive to atrophy than oxidative fibers during SD and that fat depots are reduced regardless of their location.