RESUMO
Exercise has been overlooked as a potential therapy in chronic kidney disease (CKD), mainly because of a lack of understanding on its safety aspects. Notably, there are no data on renal function after exercise in CKD considering its stages. We investigated the acute effects of a 30-min moderate-intensity aerobic exercise bout on glomerular filtration rate (GFR) and albuminuria in 22 nondialysis CKD patients divided into: CKD stages 1 and 2 (CKD1-2) and CKD stages 3 and 4 (CKD3-4). Eleven body mass index-, age-, and sex-matched healthy individuals served as control (CON). Blood and urine samples were collected before, immediately after, and up to 90 min postexercise for creatinine and albumin assessments. GFR was determined by creatinine clearance (GFRCr-Cl). All CKD patients had significantly lower peak oxygen uptake than CON. CKD1-2 and CKD3-4 had increasingly higher serum creatinine than CON (9.6 ± 2.6, 25.6 ± 1.01, and 7.5 ± 1.4 mg/l, respectively); however, no within-group changes in serum or urinary creatinine were observed across time. GFRCr-Cl was decreased in CKD1-2 and CKD3-4 compared with CON (91 ± 17 ml·min-1·1.73 m-2; 34 ± 15 ml·min-1·1.73 m-2; 122 ± 20 ml·min-1·1.73 m-2, respectively). Most importantly, exercise did not affect GFRCr-Cl in none of the groups across time. Albuminuria was significantly higher in CKD3-4 (297 ± 284 µg/min) than in CON (5.4 ± 1.4 µg/min), but no within-group changes were observed after exercise. In conclusion, a single 30-min moderate-intensity aerobic exercise bout does not impair renal function in nondialysis CKD patients, regardless of disease stage, supporting the notion that exercise training can be safe in this disease.
Assuntos
Rim/fisiopatologia , Insuficiência Renal Crônica/fisiopatologia , Adulto , Exercício Físico , Teste de Esforço , Feminino , Humanos , Testes de Função Renal , Masculino , Pessoa de Meia-IdadeRESUMO
Muscle mass is the major deposit of protein molecules with dynamic turnover between net protein synthesis and degradation. In human subjects, invasive and non-invasive techniques have been applied to determine their skeletal muscle catabolism of amino acids at rest, during and after different forms of physical exercise and training. The aim of this review is to analyse the turnover flux and the relative oxidation rate of different types of muscle proteins after one bout of exercise as well as after resistance and endurance condition of training. Protein feeding in athletes appears to be a crucial nutrition necessity to promote the maintenance of muscle mass and its adaptation to the need imposed by the imposed technical requirements. In resting human individuals, there commended protein daily allowance is about 0.8 g (dry weight) kg−body weight per 24 h knowing that humans are unable to accumulate protein stores in muscle tissues. Nevertheless, practical feeding recommendations related to regular exercise practice are proposed to athletes by different bodies in order to foster their skills and performance. This review will examine the results obtained under endurance and resistance type of exercise while consuming single or repeated doses of various ingestions of protein products (full meat, essential amino acids, specific amino acids and derivatives, vegetarian food). From the scientific literature, it appears that healthy athletes(and heavy workers) should have a common diet of 1.25 g kg−24 h to compensate the exercise training muscle protein degradation and their resyn thesis within the following hours. A nitrogen-balance assay would berecommended to avoid any excessive intake of protein. Eventually, a daily equilibrated food intake would beof primer importance versus inadequate absorption of some specific by-products.
Assuntos
Humanos , Masculino , Feminino , Criança , Adolescente , Adulto , Aminoácidos/biossíntese , Aminoácidos/metabolismo , Exercício Físico , Proteínas MuscularesRESUMO
PURPOSE OF REVIEW: Ergogenic supplements in sport events are widely used by popular and competitive athletes to enhance performance and reduce oxygen cost. Beetroot juice and nitrate salts have been increasingly used for the past 5-6 years. The present review discusses the scientific background, the efficiency and potential adverse effects of excessive nitrate supplementation. RECENT FINDINGS: There is clear evidence that nitrate from different food ingredients (such as beetroot juice and other vegetables) is converted into nitrite and possibly into nitric oxide, which may promote vasodilation, angiogenesis and mitochondrial biogenesis. The high affinity of nitric oxide towards different enzyme pathways inhibits excessive mitochondrial respiration and, therefore, tissue oxygen consumption. In addition, L-arginine supplements are proposed to stimulate nitric oxide synthesis in the endothelium. On the basis of these biochemical properties, nitrate supplementation has been suggested to athletes to enhance exercise performance. SUMMARY: The recent publications in human individuals based on L-arginine, beetroot juice or nitrate supplementation revealed either a minor positive effect or no systematic effect on exercise performance, especially in trained athletes. Of note, the sugar content of whole beetroot juice might induce a slightly more pronounced effect. Although reasonable intake of nitrate salts (up to 1âg/day) has no detrimental effect on kidney function, the risk and benefit of higher nitrate intake needs to be evaluated to define the optimal range of supplementation.
Assuntos
Desempenho Atlético , Suplementos Nutricionais , Exercício Físico , Nitratos/farmacologia , Arginina/farmacologia , Beta vulgaris/química , Humanos , Nitratos/administração & dosagem , Nitratos/metabolismoRESUMO
Physical inactivity leads to the accumulation of visceral fat and, consequently, to the activation of a network of inflammatory pathways which may promote development of insulin resistance, atherosclerosis, neurodegeneration, and tumour growth. These conditions belong to the "diseasome of physical inactivity". In contrast, the protective effect of regular exercise against diseases associated with chronic inflammation may to some extent be ascribed to an anti-inflammatory effect. The so called "acute exercise threshold", the complex mixture of several variables involved in exercise, such as type, volume, frequency, and intensity range is capable of inducing positive physiological adaptations and has been specifically addressed in the recent literature. The major concern is related to the level of the threshold: "exercise training shifts from a therapeutic adaptive intervention to one with potential pathological consequences". Nonetheless, if the mechanical stimulus is too weak to disrupt cellular homeostasis, training adaptations will not occur. Answering these questions could present practical applications, especially during inflammatory diseases associated with detrimental muscle effects and could theoretically constitute a "new" therapeutic approach to treat/improve an inflammatory state. This paper aims to describe specific data from the literature regarding the effects of exercise on inflammatory diseases in order to promote a more sophisticated perspective on the anti-inflammatory effects of exercise.
Assuntos
Terapia por Exercício/métodos , Exercício Físico , Contração Muscular/imunologia , Músculo Esquelético/fisiopatologia , Miosite/imunologia , Miosite/prevenção & controle , Humanos , Modelos ImunológicosRESUMO
Creatine (Cr) plays a central role in energy provision through a reaction catalyzed by phosphorylcreatine kinase. Furthermore, this amine enhances both gene expression and satellite cell activation involved in hypertrophic response. Recent findings have indicated that Cr supplementation has a therapeutic role in several diseases characterized by atrophic conditions, weakness, and metabolic disturbances (i.e., in the muscle, bone, lung, and brain). Accordingly, there has been an evidence indicating that Cr supplementation is capable of attenuating the degenerative state in some muscle disorders (i.e., Duchenne and inflammatory myopathies), central nervous diseases (i.e., Parkinson's, Huntington's, and Alzheimer's), and bone and metabolic disturbances (i.e., osteoporosis and type II diabetes). In light of this, Cr supplementation could be used as a therapeutic tool for the elderly. The aim of this review is to summarize the main studies conducted in this field and to highlight the scientific and clinical perspectives of this promising therapeutic supplement.
Assuntos
Doenças do Sistema Nervoso Central/tratamento farmacológico , Creatina/uso terapêutico , Suplementos Nutricionais , Doenças Metabólicas/tratamento farmacológico , Doenças Musculares/tratamento farmacológico , Doenças do Sistema Nervoso Central/metabolismo , Creatina/metabolismo , Humanos , Doenças Metabólicas/metabolismo , Doenças Musculares/metabolismo , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
The consumption of protein supplements containing amino acids is increasing around the world. Aspartate (Asp) and asparagine (Asn) are amino acids metabolized by skeletal muscle. This metabolism involves biochemical pathways that are involved in increasing Krebs cycle activity via anaplerotic reactions, resulting in higher glutamine concentrations. A connection between amino acid supplementation, glycogen concentration, and glucose uptake has been previously demonstrated. The purpose of this study was to evaluate the effect of Asp and Asn supplementation on glucose uptake in rats using three different glycogen concentrations. The results indicate that Asp and Asn supplementation in rats with high glycogen concentrations (fed state) further increased the glycogen concentration in the muscle, and decreased in vitro 2-deoxyglucose (a glucose analog) uptake by the muscle at maximal insulin concentrations. When animals had a medium glycogen concentration (consumed lard for 3 days), glucose uptake was higher in the supplemented group at sub-maximal insulin concentrations. We conclude that supplementation of Asp and Asn reduced glucose transport in rat muscle only at higher levels of glycogen. The ingestion of lard for 3 days changed the responsiveness and sensitivity to insulin, and that group had higher levels of insulin sensitivity with Asp and Asn supplementation.