ABSTRACT
Exercise, whether anaerobic or aerobic, demands the contraction of skeletal muscle. To adequately respond to an action-potential-provoking stimulus, the sarcolemma must possess a proper resting membrane potential, and this, in turn, is largely determined by the distribution of potassium ions across the sarcolemma. Such basic facts have stimulated exercise physiologists to investigate the effect of exercise on both the body content and distribution of potassium and to consider the physiologic consequences of perturbations in both. This chapter describes the dynamics of potassium in exercise. Skeletal muscle makes up approximately 40% of a person’s body weight; if one considers the standard 70-kg man, then 28 kg of his body mass is skeletal muscle which is, in turn, 75% water and contains an approximate total of 3150 meq of potassium. It would seem of interest to gather information as to how alterations in potassium distribution would affect muscle function.
