出版社：Instituto Brasileiro de Pesquisa e Ensino em Fisiologia do Exercício
摘要：During the years there have been many definitions and concepts ascribed to muscle fatigue (FM), which may represent a multifactorial phenomenon characterized by an inability to keep certain prescribed work intensity or a decline in physical capacity which is recovered after a specified time. Somehow the processes causing fatigue originate in the cortex and spinal cord are defined as central as the processes in peripheral nerves, neuromuscular junction and muscles, are defined as peripheral. A large amount of experimental models, ranging from studies in vitro, as in vivo studies have been used to understand the etiology of FM. Some mechanisms have been proposed as possible causes of central fatigue, these include: 1) increasing the concentration of metabolites during intense muscular activity, such as H +, K +, bradykinin, inorganic phosphate, prostaglandins; 2) a reduction in plasma glucose levels and; 3) increased concentration of plasma tryptophan and 5-hydroxytryptophan (5-ht); 4) and thermodynamic changes in neurotransmitter concentration. We can cite as some of the probable factors responsible for peripheral fatigue: 1) accumulation of extracellular potassium; 2) production of H+; 3) accumulation of inorganic phosphate; 4) formation of free radicals. The NaHCO3 among the most studied alkaloids in sports with high energy demands of high intensity production of H+. Studies have shown increases in performance when administered alkaloids, that despite the acidity favor some specific mechanism at the cellular level, maintaining the pH is still a crucial factor in the magnitude of fatigue. Key words: Muscular fatigue; Physical exercise; Alkaloids.
