Effects of Sleep Deprivation on Acute Skeletal Muscle Recovery after Exercise.

PURPOSE: Sleep is considered essential for muscle recovery, mainly due to its effect on hormone secretion. Total sleep deprivation or restriction is known to alter not only blood hormones but also cytokines that might be related to skeletal muscle recovery. This study aimed to evaluate whether total sleep deprivation after eccentric exercise-induced muscle damage (EEIMD) modifies the profiles of blood hormones and cytokines. METHODS: In two separate conditions, with a crossover and randomized model, 10 men (age, 24.5 ± 2.9 yr; body mass index, 22.7 ± 2.3 kg·m) performed a unilateral EEIMD protocol that comprised 240 eccentric contractions of the knee extensor muscles using an isokinetic dynamometer. In one condition, a "muscle damage" protocol was followed by 48 h of total sleep deprivation and 12 h of normal sleep (DEPRIVATION). In the other condition, the same muscle damage protocol was conducted, followed by three nights of regular sleep (SLEEP). Isometric muscle voluntary contraction tests and blood samples were collected serially throughout the protocol and analyzed for creatine kinase, free and total testosterone, IGF-1, cortisol, tumor necrosis factor-alpha, interleukin (IL)-1beta, IL-6, receptor antagonist of IL-1 and IL-10. RESULTS: Muscle voluntary contraction and serum creatine kinase increased equally over the study period in both conditions. From the cytokines evaluated, only IL-6 increased in DEPRIVATION. No differences were detected in testosterone levels between conditions, but IGF-1, cortisol, and cortisol/total testosterone ratio were higher in DEPRIVATION. CONCLUSIONS: Total sleep deprivation after EEIMD does not delay muscle strength recovery but modifies inflammatory and hormonal responses.

High-Intensity Interval Training Attenuates Insulin Resistance Induced by Sleep Deprivation in Healthy Males.

Introduction: Sleep deprivation can impair several physiological systems and recently, new evidence has pointed to the relationship between a lack of sleep and carbohydrate metabolism, consequently resulting in insulin resistance. To minimize this effect, High-Intensity Interval Training (HIIT) is emerging as a potential strategy. Objective: The aim of this study was to investigate the effects of HIIT on insulin resistance induced by sleep deprivation. Method: Eleven healthy male volunteers were recruited, aged 18-35 years, who declared taking 7-8 h sleep per night. All volunteers were submitted to four different conditions: a single night of regular sleep (RS condition), 24 h of total sleep deprivation (SD condition), HIIT training followed by regular sleep (HIIT+RS condition), and HIIT training followed by 24 h of total sleep deprivation (HIIT+SD condition). They performed six training sessions over 2 weeks and each session consisted of 8-12 × 60 s intervals at 100% of peak power output. In each experimental condition, tests for glucose, insulin, cortisol, free fatty acids, and insulin sensitivity, measured by oral glucose tolerance test (OGTT), were performed. Results: Sleep deprivation increased glycaemia and insulin levels, as well as the area under the curve. Furthermore, an increase in free fatty acids concentrations and basal metabolism was observed. There were no differences in the concentrations of cortisol. However, HIIT before 24 h of sleep deprivation attenuated the increase of glucose, insulin, and free fatty acids. Conclusion: Twenty-four hours of sleep deprivation resulted in acute insulin resistance. However, HIIT is an effective strategy to minimize the deleterious effects promoted by this condition.

REM sleep deprivation impairs muscle regeneration in rats.

INTRODUCTION: The aim was observe the influence of sleep deprivation (SD) and sleep recovery on muscle regeneration process in rats submitted to cryolesion. METHODS: Thirty-two Wistar rats were randomly allocated in four groups: control (CTL), SD for 96 h (SD96), control plus sleep recovery period (CTL + R) and SD96h plus 96 h of sleep recovery (SD96 + R). The animals were submitted to muscle injury by cryolesioning, after to SD and sleep recovery. RESULTS: The major outcomes of this study were the reduction of muscular IGF-1 in both legs (injured and uninjured) and a delay in muscle regeneration process of animals submitted to SD compared to animals that slept, with increase connective tissue, inflammatory infiltrate and minor muscle fibers. CONCLUSIONS: SD impairs muscle regeneration in rats, moreover reduces muscular IGF-1 and sleep recovery was able to restore it to basal levels, but it was not enough to normalize the muscle regeneration.

Leucine supplementation is anti-atrophic during paradoxical sleep deprivation in rats.

The purpose of this study was to identify sleep deprivation-induced atrophy and the muscle-specific fiber types affected and to determine the effects of leucine supplementation on atrophy and pertinent portions of the pathways of muscle protein synthesis and degradation in rats. A total of 46 Wistar rats were distributed in four groups: control (CTL), leucine supplementation (LEU), sleep deprivation (SD), and leucine supplementation + sleep deprivation (LEU + SD). Leucine supplementation was by gavage (1.35 g/kg/daily), and the animals were subjected to SD for 96 h. Testosterone and corticosterone concentrations, along with proteins involved in protein synthesis and degradation and proteasome activity levels, were measured in the gastrocnemius (GA) muscle. Myosin ATPase staining was used to evaluate the different muscle fibers. After sleep deprivation, GA muscle and body masses decreased in the SD group compared to the CTL, LEU, and LEU + SD groups. There was no difference between groups in type I fiber cross-sectional area (CSA). The CSAs for type IIa fibers were lower in the SD and LEU + SD groups vs. the CTL and LEU groups, while the IIb fiber CSA was lower in the SD group vs. the CSAs in all other groups. The phospho (p)-Akt levels were lower in the SD and LEU + SD groups vs. the CTL and LEU groups. The p-mTORC1 levels were higher in the LEU, SD, and LEU + SD groups vs. the CTL group. The p-p70S6k levels were higher in the LEU and LEU + SD groups; the 4E-BP1 levels were higher in the SD and LEU + SD groups compared to those in the CTL and LEU groups, and the p-4E-BP1 levels were higher in the LEU and SD groups compared to those in the CTL group and even higher in the LEU + SD group compared to those in the LEU and SD groups. Ubiquitinated proteins, LC3, and p62/SQSTM, and proteasome activity levels were higher in the SD and LEU + SD groups vs. the LEU and CTL groups. Sleep deprivation led to the atrophy of IIa and IIb muscle fibers; however, leucine supplementation prevented muscle loss and type IIb fiber atrophy.

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 body's weight loss.

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 ([Formula: see text]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.

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.

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.

Avaliação do conhecimento nutricional de mulheres fisicamente ativas e sua associação com o estado nutricional / Assessment of nutrition knowledge of women physically active and its relationship with nutritional status / Evaluación de conocimientos de nutrición de las mujeres físicamente activas y su relación con el estado nutricional

O objetivo do presente estudo foi avaliar o conhecimento nutricional de mulheres fisicamente ativas e correlacionar a pontuação obtida com variáveis antropométricas e nível de escolaridade. A amostra foi composta por 60 mulheres e os dados antropométricos mensurados foram massa corporal, estatura, Índice de Massa Corporal (massa corporal/estatura²) e perímetro da cintura. A amostra apresentou conhecimento nutricional moderado e correlações significativas foram obtidas da pontuação do questionário de conhecimento nutricional com o Índice de Massa Corporal (r = - 0,38, p < 0,05), perímetro da cintura (r = - 0,30, p < 0,05) e nível de escolaridade (r = 0,36, p < 0,05). O conhecimento nutricional pode estar associado com o estado nutricional e o nível de escolaridade.

The aim of the present study was to evaluate nutritional knowledge of women physically active and correlate it with anthropometric variables and educational level. The sample was composed by 60 women. The anthropometric variables measured were body weight, height, Body Mass Index (body weight/height²), waist circumference and nutritional knowledge. The sample demonstrated moderate nutritional knowledge and the questionnaire score was correlated with Body Mass Index (r = - 0,38, p < 0,05), waist circumference (r = - 0,30, p < 0,05) and educational level (r = 0,36, p < 0,05). The nutritional knowledge may be associated with nutritional and educational status.

El objetivo de este estudio fue evaluar el conocimiento nutricional de las mujeres que practican actividad física y correlacionar los resultados obtenidos con variables de la antropometría. La muestra comprende 60 personas y las variables analizadas son: Peso, estatura, el cálculo del Índice de Masa Corporal, perímetro de la cintura y conocimiento nutricional. Se observó que, en general, ha evaluado el conocimiento nutricional moderado. Sin embargo, hubo correlación significativa entre la puntuación del cuestionario con el índice de masa corporal (r = - 0,38), perímetro de la cintura (r = - 0,30) y nivel educativo (r = 0,36). El conocimiento nutricional puede estar asociada con el estado nutricional y educativo.

Trabalho em turnos e aspectos nutricionais: uma revisão / Shift work and nutritional aspects: a review

Shift workers are individuals more prone to having nutritional problems.Recent evidences have showed that problems such as obesity, lack of control over the food intake, insulin resistance, diabetes and dyslipidemias are more common in these individuals. This review analyzed the diet of shift workers, pointing out the main factors that are capable to change it. Current studies show that these individuals present an inadequate and in several aspects peculiar food intake pattern. On the other hand, recent data have pointed that shorter sleeping periods, desynchronization of the circadian rhythm and alteration of the environmental aspects are the main factors capable to trigger such problems. In view of the harmful effects on the nutritional status of shift workers, it is important to monitor the health ofthese individuals and encourage the development of nutritional educationprograms for this population.

Los trabajadores a turnos son individuos notadamente más predispuestos a problemas nutricionales. Diversas evidencias indican que problemas como obesidad, descontrol de la ingestión alimentaria, resistencia a la insulina, diabetes y dislipidemias son más comunes en este tipo de trabajadores. En este trabajo analizamos los datos disponibles en la literatura científ ica referente al comportamiento alimentario de trabajadores a turnos, destacando las principales modifi caciones observadas. Los estudios muestran que estos individuos presentanun padrón característico e inadecuado de ingestión alimentaria bajo varios puntos de vista. Por otro lado, datos recientes postulan que la disminución del tiempo de sueño, la alteración del ritmo circadiano y los aspectos ambientales son los principales factores capaces de desencadenar esos problemas. Considerando los factores que deterioran el equilibrio nutricional de trabajadores a turno, es importante invertir en el monitoreo de la salud y promover la elaboración de programas de educaciónnutricional dirigidos a esta población.

Trabalhadores em turnos são indivíduos conhecidamente mais predispostos a problemas nutricionais. Diversas evidências atuais têmindicado que problemas como a obesidade, descontrole da ingestão alimentar, resistência à insulina, diabetes e dislipidemias são mais comuns neste tipo de trabalhadores. Com base nisso, a presente revisão analisou os dados disponíveis na literatura científi ca referentes ao comportamento alimentar de trabalhadores em turnos, destacando os principais fatores capazes de alterá-lo. Estudos da atualidade apontam que estes indivíduos apresentam um padrão de ingestão alimentar inadequado e peculiar sobvários pontos de vista. Por outro lado, dados recentes postulam que a diminuição da duração do sono, a dessincronização do ritmo circadianoe a alteração dos aspectos ambientais são os principais fatores capazes de desencadear tais problemas. Tendo em vista os efeitos prejudiciaisno equilíbrio nutricional de trabalhadores em turnos, é importante investir no monitoramento da saúde e incentivar a elaboração de programasde educação nutricional nesta população.

Conhecimento nutricional e sua associação com o índice de massa corporal / Nutritional knowledge and its association with the body mass index

The number of individuals with excess body weight has been growingalarmingly in recent times, a fact attributed, in part, to changes in the quality of the diet consumed. The nutritional knowledge has been suggested by some researches to be able to directly infl uence food selection, and possibly may be associated with nutritional status. So, the objective of this study was to evaluate the association of nutritional knowledge level with Body Mass Index and levelof education. The sample consisted of 42 male (n=9) and female (n=33)individuals, aged 24-59 years, who were receiving nutritional monitoring ina rehabilitation center located in Sao Paulo city, Brazil. The anthropometricdata measured were body weight and height, and the Body Mass Index (bodyweight/height2) was calculated. The nutrition knowledge was measuredusing a previously validated questionnaire for the Brazilian population. It was possible to check that, generally, both groups showed moderate and low nutrition knowledge, and women had a signifi cantly higher score than men (p<0.05). However, no signifi cant correlation between the questionnaire score and the Body Mass Index were observed (r=0.16), while the latter was positively correlated with the degree of education (r=0.31, p<0.05). The results suggest that the nutritional knowledge does not seem to be determinant in food selection, and highlights the importance of nutrition strategies aimed to incorporating nutritional knowledge in promoting healthy habits.

El número de personas con exceso de peso corporal ha crecido de manera alarmante enlos últimos tiempos, un hecho atribuido, en parte, a los cambios en la calidad de la dieta consumida. El conocimiento nutricional de la población ha sido propuesto por algunos sondeos como un indicador capaz de influirdirectamente en la selección de alimentos por las personas, refl ejándose probablemente en su estadonutricional. El objetivo de este estudio fue evaluar la asociación entre el nivel de conocimiento nutricional, el Índice de Masa Corporal y la escolaridad. La muestra para este trabajo estuvocompuesta de 42 personas, nueve hombres y 33 mujeres, con edades comprendidas entre 24 y 59 años, que efectuaban acompañamientonutricional en un centro de rehabilitaciónubicado en São Paulo, Brasil. Los datosantropométricos medidos fueron peso y altura, calculándose el Índice de Masa Corporal (peso corporal/altura2). El conocimiento nutricional fue evaluado utilizando un cuestionario previamente validado para la poblaciónbrasileña. En general, es posible observar que ambos grupos mostraron conocimiento nutricional entre bajo y moderado, las mujeres con una puntuación significativamentemayor que los hombres (p<0,05). Sin embargo, no hay correlación significativa entre la puntuación en el cuestionario y el Índice de Masa Corporal (r=0,16), mientras el cuestionario se correlacionó positivamente con el grado deeducación (r=0,31, p<0,05). Los resultados sugieren que el conocimiento de nutrición no parece ser determinante para la selección de alimentos, resaltando que la incorporación deeste conocimiento es una estrategia nutricional importante en la promoción de hábitos saludables.

O número de indivíduos com excesso de peso corporal vem crescendo de maneira preocupante nos últimos tempos, fato este atribuído, emparte, pelas mudanças na qualidade da dieta consumida. O conhecimento nutricional vem sendo proposto por algumas pesquisas como umindicador capaz de influenciar diretamente a seleção alimentar e, possivelmente, se associarcom o estado nutricional. Dessa forma, o objetivo do presente estudo foi avaliar a associação do nível de conhecimento nutricional com o Índice de Massa Corporal e escolaridade. A amostra foicomposta por 42 indivíduos do gênero masculino (n=9) e feminino (n=33), com idade entre 24 e 59 anos, que realizavam acompanhamento nutricional em um centro de reabilitaçãolocalizado no município de São Paulo, Brasil. Os dados antropométricos mensurados foram peso corporal, estatura e calculado o Índice de Massa Corporal (peso corporal/estatura2).O conhecimento nutricional foi mensurado por meio de um questionário previamente validado para a população brasileira. Foi possível observar que, de modo geral, ambos os grupos apresentaram conhecimento nutricional baixo e moderado, sendo mulheres com a pontuação significativamente maior que homens (p<0,05).Porém, não houve correlação significativa entre a pontuação obtida no questionário com o Índice de Massa Corporal (r=0,16), enquantoque essa foi positivamente correlacionada com o grau de escolaridade (r=0,31; p<0,05). Osresultados obtidos sugerem que o conhecimento nutricional pareça não ser determinante na seleção alimentar, destacando-se assim aimportância de estratégias nutricionais que visem à incorporação do conhecimento em nutrição na promoção de hábitos saudáveis.

Aplicação da escala de conhecimento nutricional em atletas profissionais e amadores de atletismo / Nutrition knowledge scale application in professional and amateur track and field athletes

Uma alimentação adequada é necessária para suprir a demanda energética requerida pelo exercício tanto para esportistas como para atletas. Porém, muito mais do que o rendimento no esporte, o conhecimento sobre nutrição para prevenção de doenças é fundamental para ambas as populações. Muitas intervenções centradas na educação nutricional têm sido conduzidas com o intuito de aumentar o conhecimento nutricional da população e, conseqüentemente, melhorar seus hábitos alimentares. O presente estudo tem por objetivo avaliar o conhecimento nutricional de atletas profissionais e amadores de atletismo por meio da aplicação de uma escala previamente validada no Brasil. A amostra foi composta por 26 atletas profissionais e 41 atletas amadores de atletismo de diversas modalidades em fase de treinamento contínuo. Os resultados mostraram que atletas profissionais e amadores de atletismo apresentaram, de modo geral, conhecimento nutricional moderado, sendo que este último apresentou pontuação significativamente maior que o grupo de profissionais, fato este associado ao maior grau de instrução/escolaridade. Conclui-se que atletas profissionais de atletismo apresentam conhecimento nutricional inferior a amadores, o que pode ser atribuído, em parte, ao fato destes vivenciarem a ciência da nutrição com o objetivo primário de rendimento esportivo. Na continuidade deste estudo, novas aplicações da escala em atletas profissionais e amadores devem ser realizadas para possível afirmação do nível de conhecimento nutricional desta população.

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.

A suplementação de L-arginina promove implicações ergogênicas no exercício físico? Evidências e considerações metabólicas / Does L-arginine supplementation promote ergogenic implications on exercise? Evidences and metabolic considerations

Um número crescente de pesquisas envolvendo a suplementação de aminoácidos isolados sobre o desempenho físico vem sendo realizado, mas os efeitos e os possíveis mecanismos de ação de muitos deles ainda permanecem inconclusivos. Destes, um aminoácido que vem sendo amplamente estudado, e que já faz parte da composição de inúmeros suplementos nutricionais, é a L-arginina pelo seu possível papel na estimulação da secreção do hormônio do crescimento (GH) e da insulina, além de ser um indutor da vasodilatação dependente de óxido nítrico (NO). Diversos estudos indicam que a suplementação de L-arginina pode estimular signifi cativa secreção do GH no repouso e, quando associada ao exercício, pode promover um feedback hipotalâmico negativo com conseqüente diminuição da secreção deste hormônio. A síntese protéica muscular tem sido associado à vasodilatação promovida pela L-arginina o que, em parte, pode ser considerado errôneo pelo fato desta isoladamente não aumentar a disponibilidade de substratos para recuperação muscular. Contudo, estudos que envolvem L-arginina e desempenho esportivo, bem como aqueles investigam dose e tempo de consumo desse aminoácido, são confl itantes e refl etem a escassez de trabalhos nesse contexto. A presente revisão descreve os aspectos metabólicos e possíveis efeitos ergogênicos da suplementação de L-arginina sobre o exercício físico.

A growing number of studies involving isolated aminoacids supplementation on physical performance have been achieved, but the effects and possible mechanisms of action of many of them still remain unclear. Of these, an amino acid that has been widely studied, and that is already part of the composition of many nutritional supplements, is L-arginine for its possible role in stimulating growth hormone (GH) and insulin release, beyond to be a nitric oxide dependent vasodilation inducer (NO). Several studies indicate that L-arginine supplementation can signifi cantly stimulate basal GH release and, when associated with exercise, can promote a negative hypothalamic feedback with consequent attenuation of release. Skeletal muscle protein synthesis has been associated with L-arginine-induced vasodilation which, in part, can be considered erroneous because alone it does not increase substrates availability for muscle recovery. However, studies involving L-arginine and exercise performance, as well as those investigating dose and time of consumption of this aminoacid are confl icting and refl ect the shortage of works in this context. This review describes the metabolic aspects and possible ergogenic effects of L-arginine supplementation on exercise.

[Relation between sleep and obesity: a literature review]. / Relação entre sono e obesidade: uma revisão da literatura.

Reduction in sleep time has become an endemic condition in modern society and current literature has found important epidemiological associations between damage in the habitual standard of sleep and obesity. On this basis, the present revision analyzed the role of sleep and its alteration in the promotion of obesity. Diverse studies indicate that subjects that sleep less have greater possibility of becoming obese, and the shortening of sleep increases the leptin/ghrelin reason, generating increase of the appetite and hunger. This can be associated to the biggest caloric intake and promotion of obesity. An adequate standard of sleep becomes basic for the regulation of body mass and must be stimulated by health professionals.

Relação entre sono e obesidade: uma revisão da literatura / Relation between sleep and obesity: a literature review

A diminuição do tempo de sono tem se tornado uma condição endêmica na sociedade moderna, e a literatura atual tem encontrado importantes associações epidemiológicas entre o prejuízo no padrão habitual do sono e a obesidade. Com base nisso, a presente revisão analisou o papel do sono e da sua alteração no desencadeamento da obesidade. Diversos estudos indicam que os indivíduos que dormem menos têm uma maior possibilidade de se tornarem obesos, e que o encurtamento do sono aumenta a razão grelina/leptina, gerando o aumento do apetite e da fome. Isto pode estar associado à maior ingestão calórica e ao desencadeamento da obesidade. Dessa forma, um padrão adequado de sono torna-se fundamental para o controle da massa corporal, devendo ser incentivado pelos profissionais da saúde.

Reduction in sleep time has become an endemic condition in modern society and current literature has found important epidemiological associations between damage in the habitual standard of sleep and obesity. On this basis, the present revision analyzed the role of sleep and its alteration in the promotion of obesity. Diverse studies indicate that subjects that sleep less have greater possibility of becoming obese, and the shortening of sleep increases the leptin/grelin reason, generating increase of the appetite and hunger. This can be associated to the biggest caloric intake and promotion of obesity. An adequate standard of sleep becomes basic for the regulation of body mass and must be stimulated by health professionals.

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.