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Increased blood flow via vasodilation, metabolite production, and venous pooling contribute to the hyperemia and cellular swelling experienced during resistance training. It has been suggested that these effects play a role in hypertrophic adaptations. Over the past 2 decades, sport supplement products have been marketed to promote exercise hyperemia and intracellular fluid storage, thereby enhancing hypertrophy via acute swelling of myocytes. The three main classes of supplements hypothesized to promote exercise-induced hyperemia include vasodilators, such as nitric oxide precursor supplements; anaerobic energy system ergogenic aids that increase metabolite production, such as β-alanine and creatine; and organic osmolytes, such as creatine and betaine. Previous studies indicated that these dietary supplements are able to improve muscle performance and thus enhance muscle hypertrophy; however, recent evidences also point to these three classes of supplements affecting "secondary" physiological determinants of muscle mass accretion such as vasodilation, metabolite accumulation, and muscle cellular swelling. Although we recognize that the literature is relatively scarce regarding these topics, a better comprehension and discussion of these determinants can lead to increased knowledge and might guide further research regarding the proposed mechanisms of action of the identified compounds. In this case, increased knowledge may contribute to the development of improved efficacy, new products, or direct new research to specifically investigate those secondary effects. The aim of this review was to bring into focus new perspectives associated with secondary physiological effects induced by supplementation and to determine their relevance.

Known as a sports training method CrossFit® is a registered trademark created in the United States in the 2000s by Greg Glassman. With boxes affiliated in more than 140 countries around the world on all continents, this mode has already added more than 14,000 official training sites around the world. The training model aims to develop conditioning in general, using calisthenics exercises, basic surveys and high intensity interval training. As it is a mode that gains more followers every day, it needs attention in some details like the muscular recovery and the prescription of the alimentary diet. The objective of this research was to investigate the nutritional profile of CrossFit® practitioners. A large online questionnaire was used to track the nutritional profile of CrossFit®. The respondents answered that the main objective is health and wellness, they are consumers of food supplements and about 1/3 of those who answered the questionnaire do not have a nutrition professional prescribing their diet. According to the results, we conclude that a correct nutritional intervention can help in achieving the desired goals, avoiding poor muscle recovery and injuries.

Dietary proteins/essential amino acids (EAAs) are nutrients with anabolic properties that may increase muscle mass or attenuate muscle loss during immobilization and aging via the stimulation of muscle protein synthesis (MPS). An EAA's anabolic threshold, capable to maximize the stimulation of MPS has been hypothesized, but during certain conditions associated with muscle loss, this anabolic threshold seems to increase which reduces the efficacy of dietary EAAs to stimulate MPS. Preliminary studies have demonstrated that acute ingestion of dietary proteins/EAA (with a sufficient amount of leucine) was capable to restore the postprandial MPS during bed rest, immobilization or aging; however, whether these improvements translate into chronic increases (or attenuates loss) of muscle mass is equivocal. For example, although free leucine supplementation acutely increases MPS and muscle mass in some chronic studies, other studies have reported no increases in muscle mass following chronic leucine supplementation. In contrast, chronically increasing leucine intake via the consumption of an overall increase in dietary protein appears to be the most effective dietary intervention toward increasing or attenuating lean mass during aging; however, more research investigating the optimal dose and timing of protein ingestion is necessary. Several studies have demonstrated that decreases in postprandial MPS as a result of increased circulating oxidative and inflammatory are more responsible than muscle protein breakdown for the decreases in muscle mass during disuse and health aging. Therefore, nutritional interventions that reduce oxidation or inflammation in conjunction with higher protein intakes that overcome the anabolic resistance may enhance the MPS response to feeding and either increase muscle mass or attenuate loss. In preliminary studies, antioxidant vitamins and amino acids with antioxidant or anti-inflammatory properties show potential to restore the anabolic response associated with protein ingestion. More research, however, is required to investigate if these nutrients translate to increases in MPS and, ultimately, increased lean mass in aging humans. The purpose of the present review is to discuss the role of protein/EAA intake to enhance postprandial MPS during conditions associated with muscle loss, and bring new perspectives and challenges associated nutritional interventions aimed to optimize the anabolic effects of dietary protein/EAAs ingestion.

ObjectiveThe aim of this study was to evaluate the effects of the mixture of branched-chain amino acids (BCAAs) supplementation compared with leucine administered orally on muscle biochemical parameters of trained rats submitted to an exercise-induced protocol of glycogen depletion.MethodsAfter 6 wk of swimming exercise, 8 wk-old (250 g, adult) male Wistar rats were randomly divided into three experimental groups (n = 8 per group): the mixture of BCAAs (BCAAs), leucine (LEU), and placebo (PLA). All groups were submitted to swimming exercise for 6 wk and supplemented with either the mixture of BCAAs, leucine, or placebo during the last week of training. At week 7 of the protocol, the rats were submitted to an intermittent, progressive swimming test until exhaustion and sacrificed. Muscle gastrocnemius and liver were depicted to determine total glycogen, tricarboxylic acid cycle (TCA) intermediates, and enzymatic activities. Statistical evaluation was performed by one-way analysis of variance with Tukey post hoc test.ResultsBoth muscle and liver glycogen degradation ratio were significantly higher in the mixture of BCAAs group compared to the PLA group (P < 0.05) and the LEU group presented decreased liver glycogen degradation ratio compared with the mixture of BCAAs group (P < 0.05). Both muscle and liver glycogen content were significantly spared in the mixture of BCAAs and LEU groups compared to the PLA group (P < 0.01). A performance test demonstrated that LEU supplementation enhanced resistance to exhaustion compared to the mixture of BCAAs (P < 0.001), however, no difference was found when LEU supplementation was compared to PLA (P > 0.05) Muscle citrate content was significantly higher in the mixture of BCAAs group compared with the PLA group (P < 0.001). Muscle malate content was significantly elevated in the mixture of BCAAs group compared with both the PLA (P < 0.001) and LEU groups (P < 0.001). BCAT activity was significantly reduced in the mixture of BCAAs supplementation group compared with the LEU group (P < 0.001).ConclusionLeucine supplementation improved performance compared with the mixture of BCAAs supplementation, sparing muscle glycogen stores despite the augmentation of some TCA intermediate concentrations on the left side of the TCA cycle.

Branched-chain amino acids (BCAA) (especially leucine) have been shown to activate protein synthesis pathways, decrease proteolysis and increase insulin sensitivity. Furthermore, it appears that leucine can be used as a nutritional therapy to avoid sarcopenia and skeletal muscle atrophy due to immobilization or glucocorticoid treatment. However, it is of note that all of these conditions are related to insulin resistance to varying degrees and affect different tissues, particularly skeletal muscle. Additionally, evidence from recent studies demonstrate that a combination of protein containing high levels of leucine with nutrients containing saturated fatty acids or an excess of leucine are capable of inducing insulin resistance. From this discussion, a few major questions arise. First, what is the role of a combination of macronutrients in inducing insulin resistance? Second, in insulin resistance, does leucine supplementation follow the same path observed under healthy conditions? Finally, what are the dose-dependent outcome and the latency of leucine effect under such conditions? The present article discusses these questions based on data from the literature and experiments performed by our group.

The reduction of skeletal muscle loss in pathological states, such as muscle disuse, has considerable effects in terms of rehabilitation and quality of life. Since there is no currently effective and safe treatment available for skeletal muscle atrophy, the search for new alternatives is necessary. Resistance exercise (RE) seems to be an important tool in the treatment of disuse-induced skeletal muscle atrophy by promoting positive functional (strength and power) and structural (hypertrophy and phenotypic changes) adaptive responses. Human and animal studies using different types of resistance exercise (flywheel, vascular occlusion, dynamic, isometric, and eccentric) have obtained results of great importance. However, since RE is a complex phenomenon, lack of strict control of its variables (volume, frequency, intensity, muscle action, rest intervals) limits the interpretation of the impact of the manipulation on skeletal muscle remodeling and function under disuse. The aim of this review is to critically describe the functional and morphological role of resistance exercise in disuse-induced skeletal muscle atrophy with emphasis on the principles of training.

We aimed to investigate the possible role of creatine (CR) supplementation in counteracting dexamethasone-induced muscle wasting and insulin resistance in rats. Also, we examined whether CR intake would modulate molecular pathways involved in muscle remodeling and insulin signaling. Animals were randomly divided into four groups: (1) dexamethasone (DEX); (2) control pair-fed (CON-PF); (3) dexamethasone plus CR (DEX-CR); and (4) CR pair-fed (CR-PF). Dexamethasone (5 mg/kg/day) and CR (5 g/kg/day) were given via drinking water for 7 days. Plantaris and extensor digitorum longus (EDL) muscles were removed for analysis. Plantaris and EDL muscle mass were significantly reduced in the DEX-CR and DEX groups when compared with the CON-PF and CR-PF groups (P

Glucocorticoid hormones are important regulators of several physiological processes. Despite having been initially named based on their role in glucose metabolism, glucocorticoids are also fundamental in the regulation of developmental, metabolic, and neurobiological processes, as well as several other biological functions. Due to their involvement in a diverse array of biological pathways, its wide spectrum of action, it is predicted that a wide range of genes may have their expression regulated by the activated glucocorticoid receptor (GR). In fact, it has been demonstrated that in addition to the regulation of several effectors genes, the expression of the gene encoding for GR itself is regulated by physiological stimuli and fine-tuning mechanisms. Importantly, such generalized effector responses and fine-tuning responses seem to be largely mediated by mechanisms of gene regulation. Therefore, this review aims to describe the mechanisms of gene regulation by glucocorticoid hormones, which are capable of regulating differential gene transcription, within a physiological context. From this discussion, we hope to shed light on how a single molecule that is capable of exerting such divergent effects is also capable of promoting such distinct responses in different target tissues.

Resumo Objetivo: Descrever o perfil antropométrico e a composição corporal de idosos por meio da antropometria, analisando a aplicabilidade das equações de predição de Petroski (1995) e de Durnin & Womersley (1974).Métodos: Foram avaliados 37 idosos de ambos os gêneros. As medições antropométricas foram realizadas segundo as diretrizes daInternational Society for the Advancement of Kineanthropometry, e determinaram as variáveis massa corporal, estatura, oito dobras cutâneas e sete perímetros musculares. Calcularam-se índice de massa corporal (IMC), relação cintura-quadril (RCQ), somatório de cinco dobras cutâneas e densidade corporal pelas equações de predição para idosos de Petroski (1995) e de Durnin & Womersley (1974) com conversão ao percentual de gordura (%G) pela equação de Siri (1961). Para posterior discussão, aplicou-se o teste t Student (p

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.

Leucine, one of the three branched chain amino acids (BCAAs) with isoleucine and valine, is an essential amino acid that has emerged due its potential ergogenic and therapeutic role in both exercise (especially resistance exercise) and some diseases (i.e., cancer, muscle disuse, and sarcopenia), respectively. Besides its role in energy provision as a nitrogen donor for muscle alanine synthesis, leucine is also a trigger amino acid that can modulate some cellular pathways involved in skeletal muscle protein synthesis and degradation, innate immune system (inflammation), and insulin secretion.

The aim of this commentary was to discuss the last studies regarding the effect of antioxidant vitamins supplementation on oxidative stress in exercise in humans. The inclusion criteria encompassed published studies done in adult males and females between 2006 and 2013. The keywords used in the search engine were: endurance athlete, diet, oxidative stress, physical activity, diet, nutrition, antioxidant, antioxidant status, vitamin C, vitamin A, vitamin E, β-carotene and combinations. Twelve studies were identified and organized according to the methodology and results of supplementation: ergogenic, ergolytic, partial or no difference between groups. The results of these studies showed no effect on physiological parameters and activity of antioxidant enzymes (n = 07), better response of the placebo treatment (ergolytic effect; n = 02), partial results (n = 01) and ergogenic results of antioxidant supplementation (n = 02). It is concluded that supplementation with antioxidant vitamins has controversial effects to oxidative damage induced by endurance exercise. The discordances among the studies are presented and discussed.

Branched-chain amino acids (BCAAs), mainly leucine, have been described as potential modulators of resistance exercise-induced muscle adaptations which includes stimulation of muscle protein synthesis and attenuation of proteolysis. However, until the moment, there are no well controlled chronic studies (randomized, doubleblind and placebo-controlled) in humans assessing the effects of BCAAs/leucine supplementation on muscle hypertrophy and strength. The most well documented benefits of BCAAs/leucine concerning exercise is the attenuation of muscle damage and soreness. Previous reports support the theory that BCAAs/leucine could act through innate immunity. However, recent studies have demonstrated similar effects in humans with β-hydroxy-β-methylbutyrate (HMβ) supplementation. Since HMβ is a leucine metabolite, it appears that there is a metabolic relation among BCCAs/leucine, HMβ and the attenuation of exercise-induced muscle damage.

Sarcopenia describes an age-related decline in skeletal muscle mass, strength, and function that ultimately impairs metabolism, leads to poor balance, frequent falling, limited mobility, and a reduction in quality of life. Here we investigate the pathogenesis of sarcopenia through a proteomic shotgun approach. Briefly, we employed tandem mass tags (TMT) to quantitate and compare the protein profiles obtained from young versus old rat slow-twitch type of muscle (soleus) and a fast-twitch type of muscle (extensor digitorum longus, EDL). Our results disclose 3452 and 1848 proteins identified from soleus and EDL muscles samples of which 78 and 174 were found to be differentially expressed, respectively. In general, most of the proteins were structural related, involved in energy metabolism, oxidative stress, detoxification, or transport. Aging affected soleus and EDL muscles differently and several proteins were regulated in opposite ways. For example, pyruvate kinase had its expression and activity different in both soleus and EDL muscles. We were able to verify with existing literature many of our differentially expressed proteins as candidate aging biomarkers, and most importantly, disclose several new candidate biomarkers such as the glioblastoma amplified sequence (GAS), zero beta-globin, and prolargin.

Protein consumption as well as the effects of isolated amino acids have long been studied for their possible ergogenic effects on skeletal muscle mass and strength. This chapter discusses in detail the role of specific amino acids, namely the branched-chain amino acids (BCAAs), especially leucine, regarding their metabolism, the molecular pathways they activate in skeletal muscle and their physiological effects. Studies regarding the effects of protein and amino acids supplementation on gain of muscle mass and strength are discussed with an emphasis on the activation of key proteins (such as mTOR and p70S6k) that, once phosphorylated, are able to stimulate the initiation of protein synthesis. The effects of different sources of protein, dose and timing and their physiological effects are also discussed. The last section gives practical recommendations regarding amino acid and protein supplementation, their safety, as well as the possible side effects when amino acids are given under specific metabolic conditions.

We examined the capacity of high-intensity intermittent training (HI-IT) to facilitate the delivery of lipids to enzymes responsible for oxidation, a task performed by the carnitine palmitoyl transferase (CPT) system in the rat gastrocnemius muscle. Male adult Wistar rats (160-250 g) were randomly distributed into 3 groups: sedentary (Sed, N = 5), HI-IT (N = 10), and moderate-intensity continuous training (MI-CT, N = 10). The trained groups were exercised for 8 weeks with a 10% (HI-IT) and a 5% (MI-CT) overload. The HI-IT group presented 11.8% decreased weight gain compared to the Sed group. The maximal activities of CPT-I, CPT-II, and citrate synthase were all increased in the HI-IT group compared to the Sed group (P < 0.01), as also was gene expression, measured by RT-PCR, of fatty acid binding protein (FABP; P < 0.01) and lipoprotein lipase (LPL; P < 0.05). Lactate dehydrogenase also presented a higher maximal activity (nmol·min -1 ·mg protein ) in HI-IT (around 83%). We suggest that 8 weeks of HI-IT enhance mitochondrial lipid transport capacity thus facilitating the oxidation process in the gastrocnemius muscle. This adaptation may also be associated with the decrease in weight gain observed in the animals and was concomitant to a higher gene expression of both FABP and LPL in HI-IT, suggesting that intermittent exercise is a “time-efficient” strategy inducing metabolic adaptation. Key words: High-intensity intermittent training; Lipid metabolism; Carnitine palmitoyl transferase

INTRODUÇÃO: Recentes evidências indicam que a suplementação de creatina (Cr) é capaz de aumentar a densidade mineral óssea (DMO) no fêmur de ratos saudáveis em crescimento. Entretanto, há poucos estudos que testam a efetividade da suplementação desse nutriente em condições de perda óssea. OBJETIVO: Investigar o efeito da suplementação de Cr na DMO e no conteúdo mineral ósseo (CMO) de ratos espontaneamente hipertensos (SHR), um modelo experimental de baixa massa óssea. MATERIAIS E MÉTODOS: Dezesseis ratos SHR machos com 8 meses de idade foram randomizados em dois grupos experimentais pareados pelo peso corporal, a saber: 1) Pl: SHR tratados com placebo (água destilada; n = 8); e 2) Cr: SHR tratados com Cr (n = 8). Após nove semanas de suplementação os animais foram eutanasiados e o fêmur e a coluna vertebral (L1-L4) foram analisados por densitometria óssea (Dual Energy X-Ray Absorptiometry). RESULTADOS: Não houve diferença significativa na DMO (Pl = 0,249 ± 0,003 g/cm² vs. Cr = 0,249 ± 0,004 g/cm²; P = 0,95) e no CMO (Pl = 0,509 ± 0,150 g vs. Cr = 0,509 ± 0,017 g; P = 0,99) da coluna vertebral e na DMO (Pl = 0,210 ± 0,004 g/cm² vs. Cr = 0,206 ± 0,004 g/cm2;P = 0,49) e no CMO (Pl = 0,407 ± 0,021 g vs. Cr = 0,385 ± 0,021 g; P = 0,46) do fêmur total entre os grupos experimentais. CONCLUSÃO: Neste estudo, usando um modelo experimental de baixa massa óssea, a suplementação de Cr não afetou a massa óssea. INTRODUCTION: Recent evidence has suggested that creatine supplementation (Cr) can increase the bone mineral density (BMD) of the femur in healthy growing rats. Nevertheless, studies assessing the efficacy of the Cr supplementation in conditions characterized by bone mass loss are scarce. OBJECTIVE: To investigate the effect of Cr supplementation on BMD and bone mineral content (BMC) in spontaneously hypertensive rats (SHRs), an experimental model of osteoporosis. MATERIALS AND METHODS: Sixteen 8-month-old male SHRs were randomly allocated into two groups matched by body weight: 1) Pl group: SHRs treated with placebo (distilled water; n = 8); and 2) Cr group: SHRs treated with Cr (n = 8). After nine weeks of supplementation, the animals were euthanized and their femur and spine (L1-L4) were analyzed by use of densitometry (Dual Energy X-Ray Absorptiometry). RESULTS: No significant difference was observed between the groups regarding either the spine or the total femur measures as follows: spine - BMD (Pl = 0.249 ± 0.003 g/cm² vs. Cr = 0.249 ± 0.004 g/cm²; P = 0.95) and BMC (Pl = 0.509 ± 0.150 g vs. Cr = 0.509 ± 0.017 g; P > 0.99); and total femur - BMD (Pl = 0.210 ± 0.004 g/cm² vs. Cr = 0.206 ± 0.004 g/cm²; P > 0.49) and BMC (Pl = 0.407 ± 0.021 g vs. Cr = 0.385 ± 0.021 g; P > 0.46). CONCLUSION: In this study, using the experimental model of osteoporosis, Cr supplementation had no effect on bone mass.

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Objective: We aimed to evaluate the effects of resistance exercise (RE) and leucine (LEU) supplementation on dexamethasone (DEXA)-induced muscle atrophy and insulin resistance.Methods: Male Wistar rats were randomly divided into DEXA(DEX), DEXA + RE (DEX-RE), DEXA + LEU (DEX-LEU), and DEXA + RE + LEU (DEX-RE-LEU) groups. Each group received DEXA 5 mg . kg(-1) . d(-1) for 7 d from drinking water and were pair-fed to the DEX group; LEU-supplemented groups received 0.135 g . kg(-1) . d(-1) through gavage for 7 d; the RE protocol was based on three sessions of squat-type exercise composed by three sets of 10 repetitions at 70% of maximal voluntary strength capacity.Results: the plantaris mass was significantly greater in both trained groups compared with the non-trained groups. Muscle cross-sectional area and fiber areas did not differ between groups. Both trained groups displayed significant increases in the number of intermediated fibers (IIa/IIx), a decreased number of fast-twitch fibers (IIb), an increased ratio of the proteins phospho(Ser2448)/ total mammalian target of rapamycin and phospho(Thr389)/total 70-kDa ribosomal protein S6 kinase. and a decreased ratio of phospho(Ser253)/total Forkhead box protein-3a. Plasma glucose was significantly increased in the DEX-LEU group compared with the DEX group and RE significantly decreased hyperglycemia. the DEX-LEU group displayed decreased glucose transporter-4 translocation compared with the DEX group and RE restored this response. LEU supplementation worsened insulin sensitivity and did not attenuate muscle wasting in rats treated with DEXA. Conversely, RE modulated glucose homeostasis and fiber type transition in the plantaris muscle.Conclusion: Resistance exercise but not LEU supplementation promoted fiber type transition and improved glucose homeostasis in DEXA-treated rats. (C) 2012 Elsevier Inc. All rights reserved. Univ São Paulo, Lab Appl Nutr & Metab, Sch Phys Educ & Sports, São Paulo, Brazil Univ São Paulo, Inst Biomed Sci, São Paulo, Brazil Univ São Paulo, Lab Mol & Cellular Physiol Exercise, Sch Phys Educ & Sports, São Paulo, Brazil Univ São Paulo, Sch Med, Lab Expt Hypertens, São Paulo, Brazil Universidade Federal de São Paulo, Dept Biosci, São Paulo, Brazil Clermont Univ, UFR Med, UMR Nutr Humaine 1019, Clermont Ferrand, France INRA, UMR Unite Nutr Humaine 1019, F-63122 St Genes Champanelle, France Universidade Federal de São Paulo, Dept Biosci, São Paulo, Brazil FAPESP: 08/51090-1 FAPESP: 10/07062-3 FAPESP: 10/10852-6 FAPESP: 11/04690-6 Web of Science

Dexamethasone (DEXA) is a potent immunosupressant and anti-inflammatory agent whose main side effects are muscle atrophy and insulin resistance in skeletal muscles. In this context, leucine supplementation may represent a way to limit the DEXA side effects. In this study, we have investigated the effects of a low and a high dose of leucine supplementation (via a bolus) on glucose homeostasis, muscle mass and muscle strength in energy-restricted and DEXA-treated rats. Since the leucine response may also be linked to the administration of this amino acid, we performed a second set of experiments with leucine given in bolus (via gavage) versus leucine given via drinking water. Leucine supplementation was found to produce positive effects (e. g., reduced insulin levels) only when administrated in low dosage, both via the bolus or via drinking water. However, under DEXA treatment, leucine administration was found to significantly influence this response, since leucine supplementation via drinking water clearly induced a diabetic state, whereas the same effect was not observed when supplied via the gavage.

This study aimed to develop an equipment and system of resistance exercise (RE), based on squat-type exercise for rodents, with control of training variables. We developed an operant conditioning system composed of sound, light and feeding devices that allowed optimized RE performance by the animal. With this system, it is not necessary to impose fasting or electric shock for the animal to perform the task proposed (muscle contraction). Furthermore, it is possible to perform muscle function testsin vivowithin the context of the exercise proposed and control variables such as intensity, volume (sets and repetitions), and exercise session length, rest interval between sets and repetitions, and concentric strength. Based on the experiments conducted, we demonstrated that the model proposed is able to perform more specific control of other RE variables, especially rest interval between sets and repetitions, and encourages the animal to exercise through short-term energy restriction and “disturbing” stimulus that do not promote alterations in body weight. Therefore, despite experimental limitations, we believe that this RE apparatus is closer to the physiological context observed in humans.

Recent evidence has suggested that creatine supplementation (Cr) can increase the bone mineral density (BMD) of the femur in healthy growing rats. Nevertheless, studies assessing the efficacy of the Cr supplementation in conditions characterized by bone mass loss are scarce.To investigate the effect of Cr supplementation on BMD and bone mineral content (BMC) in spontaneously hypertensive rats (SHRs), an experimental model of osteoporosis.Sixteen 8-month-old male SHRs were randomly allocated into two groups matched by body weight: 1) Pl group: SHRs treated with placebo (distilled water; n = 8); and 2) Cr group: SHRs treated with Cr (n = 8). After nine weeks of supplementation, the animals were euthanized and their femur and spine (L1-L4) were analyzed by use of densitometry (Dual Energy X-Ray Absorptiometry).No significant difference was observed between the groups regarding either the spine or the total femur measures as follows: spine - BMD (Pl = 0.249 ± 0.003 g/cm² vs. Cr = 0.249 ± 0.004 g/cm²; P = 0.95) and BMC (Pl = 0.509 ± 0.150 g vs. Cr = 0.509 ± 0.017 g; P0.99); and total femur - BMD (Pl = 0.210 ± 0.004 g/cm² vs. Cr = 0.206 ± 0.004 g/cm²; P0.49) and BMC (Pl = 0.407 ± 0.021 g vs. Cr = 0.385 ± 0.021 g; P0.46).In this study, using the experimental model of osteoporosis, Cr supplementation had no effect on bone mass.

The characterization of the mechanisms underlying skeletal muscle atrophy under different conditions has been a constant focus of research. Among anti-atrophic therapies, amino acid supplementation, particularly with leucine, has received a lot of attention. Supplementation has been shown to have remarkable effects on muscle remodeling through protein turnover modulation. This may then impact physiological parameters related to muscle function, and even quality of life. In light of this, leucine supplementation could be a useful therapy for mitigating the atrophic effects of catabolic conditions. The purpose of this review is to present the major results of human studies evaluating the effects of leucine supplementation on structure and function of skeletal muscle in atrophic conditions such as muscle disuse, sarcopenia, and cancer.

Judo competitions are divided into weight classes. However, most athletes reduce their body weight in a few days before competition in order to obtain a competitive advantage over lighter opponents. To achieve fast weight reduction, athletes use a number of aggressive nutritional strategies so many of them place themselves at a high health-injury risk. In collegiate wrestling, a similar problem has been observed and three wrestlers died in 1997 due to rapid weight loss regimes. After these deaths, the National Collegiate Athletic Association had implemented a successful weight management program which was proven to improve weight management behavior. No similar program has ever been discussed by judo federations even though judo competitors present a comparable inappropriate pattern of weight control. In view of this, the basis for a weight control program is provided in this manuscript, as follows: competition should begin within 1 hour after weigh-in, at the latest; each athlete is allowed to be weighed-in only once; rapid weight loss as well as artificial rehydration (i.e., saline infusion) methods are prohibited during the entire competition day; athletes should pass the hydration test to get their weigh-in validated; an individual minimum competitive weight (male athletes competing at no less than 7% and females at no less than 12% of body fat) should be determined at the beginning of each season; athletes are not allowed to compete in any weight class that requires weight reductions greater than 1.5% of body weight per week. In parallel, educational programs should aim at increasing the athletes', coaches' and parents' awareness about the risks of aggressive nutritional strategies as well as healthier ways to properly manage body weight.

The purpose of present review is to describe the effect of leucine supplementation on skeletal muscle proteolysis suppression in both in vivo and in vitro studies. Most studies, using in vitro methodology, incubated skeletal muscles with leucine with different doses and the results suggests that there is a dose-dependent effect. The same responses can be observed in in vivo studies. Importantly, the leucine effects on skeletal muscle protein synthesis are not always connected to the inhibition of skeletal muscle proteolysis. As a matter of fact, high doses of leucine incubation can promote suppression of muscle proteolysis without additional effects on protein synthesis, and low leucine doses improve skeletal muscle protein ynthesis but have no effect on skeletal muscle proteolysis. These research findings may have an important clinical relevancy, because muscle loss in atrophic states would be reversed by specific leucine supplementation doses. Additionally, it has been clearly demonstrated that leucine administration suppresses skeletal muscle proteolysis in various catabolic states. Thus, if protein metabolism changes during different atrophic conditions, it is not surprising that the leucine dose-effect relationship must also change, according to atrophy or pathological state and catabolism magnitude. In conclusion, leucine has a potential role on attenuate skeletal muscle proteolysis. Future studies will help to sharpen the leucine efficacy on skeletal muscle protein degradation during several atrophic states.

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.

In the beginning of the last century, muscle proteins were viewed as static structural molecules not capable of being utilized by other tissues or organs. This concept was accepted until the 30s, where Rudolf Schoenheimer presented strong evidences about the “Dynamic State of Body Constituents,” which means that skeletal muscle is not only capable of contracting but also capable of releasing nitrogen derived molecules to be utilized by other organs and tissues (Guggenheim, 1991) [1]. Such concept established that skeletal muscle is a highly plastic tissue, adapting its structure and metabolism in response to diverse conditions such as contractile activity, mechanical overload, and nutrients. From this point of view several questions arise, specifically, how form follows function of skeletal muscles, as well as the synergistic role of nutrients. A large number of research groups around the world are helping to clarify this and many other questions. In particular in the last four decades, the growth in the number of publications on skeletal muscle subject is noteworthy (Figure 1). Figure 1 Number of publications in Medline database with “skeletal muscle” present on title. Data from the US National Library of Medicine National Institutes of Health (http://www.ncbi.nlm.nih.gov/pubmed?term=skeletal%20muscle [Title]). ... In this special issue, the reader will be brought directly to a wide spectrum of articles regarding the skeletal muscle tissue. From France, a new hypothesis concerning how to consume amino acids and deal with catabolic conditions also is put in debate, focusing on the anabolic threshold concept (D. Dardevet et al., 2012). From the University of Tokyo, Japan, A. Wagatsuma and K. Sakuma (2013) summarize the current knowledge about the role of mitochondria as a regulator of myogenesis. From Brazil, C. O. Assumpcao et al. (2013) present an extensive review on the effects of exercise-induced muscle damage on running economy in humans. Also, W. S. Dantas et al. (2013) discuss the impact of polycystic ovary syndrome on skeletal muscle tissue. A. Carsana (2013), from Italy, reviewed the documented cases of exertional rhabdomyolysis or stress-induced malignant hyperthermia and reported a possible association with RYR1 gene polymorphism. This special issue also presents original articles focusing on the cytokine response of skeletal muscle cells according its differentiation stage (M. Podbregar et al., 2013), the effects of tissue culture conditions on in vitro myogenesis (S. Hinds et al., 2013) and the differences in spontaneous physical activity between mice substrains (D. Coletti et al., 2013). All these discussions are being provided in order to generate new benefits and from athletes to debilitated populations; from basic to applied sciences. In this issue, our focus was not to restrict but, on the contrary, to be capable of proposing new hypotheses and ideas based on the current knowledge.

The impact of leucine supplementation and resistance exercise (RE) on plasma lipid profile was evaluated in adult rats treated with dexamethasone, an experimental model of dyslipidemia. Total cholesterol did not differ among groups. Furthermore, leucine supplementation did not promote improvement in the plasma total cholesterol and LDL-c of the animals. However, plasma TG and VLDL-c were significantly decreased and HDL-c increased after 7 days of leucine supplementation combined with RE. In conclusion, leucine supplementation combined with RE, but not isolated, improved the plasma lipid profile of dexamethasone-induced dyslipidemic rats.

It is well known that carbohydrate (CHO) supplementation can improve performance in endurance exercises through several mechanisms such as maintenance of glycemia and sparing endogenous glycogen as well as the possibility of a central nervous-system action. Some studies have emerged in recent years in order to test the hypothesis of ergogenic action via central nervous system. Recent studies have demonstrated that CHO mouth rinse can lead to improved performance of cyclists, and this may be associated with the activation of brain areas linked to motivation and reward. These findings have already been replicated in other endurance modalities, such as running. This alternative seems to be an attractive nutritional tool to improve endurance exercise performance.

Background Exacerbated oxidative stress is thought to be a mediator of arterial hypertension. It has been postulated that creatine (Cr) could act as an antioxidant agent preventing increased oxidative stress. The aim of this study was to investigate the effects of nine weeks of Cr or placebo supplementation on oxidative stress and cardiovascular parameters in spontaneously hypertensive rats (SHR). Findings Lipid hydroperoxidation, one important oxidative stress marker, remained unchanged in the coronary artery (Cr: 12.6 ± 1.5 vs. Pl: 12.2 ± 1.7 nmol·mg-1; p = 0.87), heart (Cr: 11.5 ± 1.8 vs. Pl: 14.6 ± 1.1 nmol·mg-1; p = 0.15), plasma (Cr: 67.7 ± 9.1 vs. Pl: 56.0 ± 3.2 nmol·mg-1; p = 0.19), plantaris (Cr: 10.0 ± 0.8 vs. Pl: 9.0 ± 0.8 nmol·mg-1; p = 0.40), and EDL muscle (Cr: 14.9 ± 1.4 vs. Pl: 17.2 ± 1.5 nmol·mg-1; p = 0.30). Additionally, Cr supplementation affected neither arterial blood pressure nor heart structure in SHR (p > 0.05). Conclusions Using a well-known experimental model of systemic arterial hypertension, this study did not confirm the possible therapeutic effects of Cr supplementation on oxidative stress and cardiovascular dysfunction associated with arterial hypertension.

Branched-chain amino acids (BCAA) supplementation has been considered an interesting nutritional strategy to improve skeletal muscle protein turnover in several conditions. In this context, there is evidence that resistance exercise (RE)-derived biochemical markers of muscle soreness (creatine kinase (CK), aldolase, myoglobin), soreness, and functional strength may be modulated by BCAA supplementation in order to favor of muscle adaptation. However, few studies have investigated such effects in well-controlled conditions in humans. Therefore, the aim of this short report is to describe the potential therapeutic effects of BCAA supplementation on RE-based muscle damage in humans. The main point is that BCAA supplementation may decrease some biochemical markers related with muscle soreness but this does not necessarily reflect on muscle functionality.