This study investigated the prevalence, magnitude, and methods of rap-id weight loss among male and female Taekwondo athletes from all competitive levels. A questionnaire was administered to 72 men (regional/state level, n=31; national/international level, n=41) and 44 women (regional/state level, n=9; national/international, n=35). Among the male athletes, 77.4% of the regional/state level and 75.6% of the national/international athletes declared to have reduced weight to compete in lighter weight categories. Among women, 88.9% of regional/state level and 88.6% of national/international level reported the use of rapid weight loss strategies. Athletes reported to usually lose ~3% of their body weight, with some athletes reaching ~7% of their body weight. The methods used to achieve weight loss are potentially dangerous to health and no difference between sexes was found. Four methods were more frequently used by men athletes in higher competitive levels as compared to lower levels, as follows: skipping meals (Z=2.28, P=0.023, η2=0.21), fasting (Z=2.337, P=0.019, η2=0.22), restricting fluids (Z=2.633, P=0.009, η2=0.24) and spitting (Z=2.363, P=0.018, η2=0.22). Taekwondo athletes lost ~3% of their body mass, using methods potentially dangerous for their health. Although no difference was found between sexes, lower level athletes more frequently used methods such as skipping meals, fasting, restricting fluids and spitting. Considering that these health-threating methods are more commonly used by lower level athletes, specific education programs should be directed to them.

Carnosine is a pleiotropic histidine-containing dipeptide synthesized from β-alanine and l-histidine, with the intact dipeptide and constituent amino acids being available from the diet. The therapeutic application of carnosine in myocardial tissue is promising, with carnosine playing a potentially beneficial role in both healthy and diseased myocardial models. This narrative review discusses the role of carnosine in myocardial function and health, including an overview of the metabolic pathway of carnosine in the myocardial tissue, the roles carnosine may play in the myocardium, and a critical analysis of the literature, focusing on the effect of exogenous carnosine and its precursors on myocardial function. By so doing, we aim to identify current gaps in the literature, thereby identifying considerations for future research.

RESUMOEstudos recentes têm sugerido que a suplementação de creatina é capaz de modular a homeostase da glicose, aumentando sua captação pelos tecidos periféricos. O objetivo deste trabalho foi investigar o efeito da suplementação de creatina na tolerância à glicose e no conteúdo de glicogênio muscular e hepático em ratos submetidos ou não à atividade física por quatro e oito semanas. Ratos Wistar foram divididos em dois grupos: quatro e oito semanas de intervenção. Posteriormente, cada grupo foi subdividido em quatro subgrupos, de acordo com a ingestão do suplemento e o treinamento: controle cedentário, controle treinado, suplementado sedentário e suplementado treinado. Os animais tiveram livre acesso à água e ração; o grupo suplementado teve 2% de sua ração sob a forma de creatina monoidratada. Os grupos exercitados nadaram 40 minutos por dia, quatro dias por semana, com carga entre 2 e 5% do seu peso amarrado ao peito. Após quatro e oito semanas, o teste oral de tolerância à glicose e as dosagens de glicogênio muscular e hepático foram realizadas. Não foram observadas diferenças significativas entre os grupos no teste de tolerância oral à glicose e no conteúdo de glicogênio muscular e hepático. Este estudo mostrou que a suplementação de creatina não exerceu influência na tolerância à glicose nem nas concentrações de glicogênio em ratos submetidos ou não à atividade física por quatro ou oito semanas.Palavras-chave: àcido α metil guanidino acético, condicionamento físico, glicemia. ABSTRACTRecently, studies have suggested that creatine supplementation can modulate glucose homeostasis by increasing glucose uptake in peripheral tissues. The aim of this study was to investigate the effects of creatine supplementation on glucose tolerance, muscle and hepatic glycogen content in rats submitted or not to physical activity for four and eight weeks. Wistar rats were divided in two groups: four and eight weeks of intervention. Afterwards, each group was subdivided in four subgroups, according to supplement intake and exercise: Sedentary Control; Trained Control; Supplemented Sedentary; and Supplemented Trained. The animals had free access to water and chow and the supplemented groups had two % of their diet as creatine monohydrated. The exercise groups swam for 40 minutes a day, four days a week, with two to five % of their body weight attached to their chests. After four and eight weeks, oral glucose tolerance tests were performed and both hepatic and muscle glycogen were determined. No significant differences were observed between groups on glucose tolerance and glycogen content in muscle and hepatic tissue. This study shows that creatine supplementation does not influence neither glucose tolerance nor glycogen concentrations in rats submitted or not to physical activity for four and eight weeks.

In the present study we have compared the effects of leucine supplementation and its metabolite β-hydroxy-β-methyl butyrate (HMB) on the ubiquitin-proteasome system and the PI3K/Akt pathway during two distinct atrophic conditions, hindlimb immobilization and dexamethasone treatment. Leucine supplementation was able to minimize the reduction in rat soleus mass driven by immobilization. On the other hand, leucine supplementation was unable to provide protection against soleus mass loss in dexamethasone treated rats. Interestingly, HMB supplementation was unable to provide protection against mass loss in all treatments. While solely fiber type I cross sectional area (CSA) was protected in immobilized soleus of leucine-supplemented rats, none of the fiber types were protected by leucine supplementation in rats under dexamethasone treatment. In addition and in line with muscle mass results, HMB treatment did not attenuate CSA decrease in all fiber types against either immobilization or dexamethasone treatment. While leucine supplementation was able to minimize increased expression of both Mafbx/Atrogin and MuRF1 in immobilized rats, leucine was only able to minimize Mafbx/Atrogin in dexamethasone treated rats. In contrast, HMB was unable to restrain the increase in those atrogenes in immobilized rats, but in dexamethasone treated rats, HMB minimized increased expression of Mafbx/Atrogin. The amount of ubiquitinated proteins, as expected, was increased in immobilized and dexamethasone treated rats and only leucine was able to block this increase in immobilized rats but not in dexamethasone treated rats. Leucine supplementation maintained soleus tetanic peak force in immobilized rats at normal level. On the other hand, HMB treatment failed to maintain tetanic peak force regardless of treatment. The present data suggested that the anti-atrophic effects of leucine are not mediated by its metabolite HMB.

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