Physiological Society

Insulin increases the uptake of glucose by the muscles, promotes the synthesis of glycogen, inhibits lipolysis and increases lipid synthesis; therefore it has been speculated that age-dependent changes in blood insulin concentration might influence metabolic characteristics. Supporting data are, however, not convincing. In one of the most comprehensive studies, Wirth et al (1978) determined the [...]

Oxidative metabolism is relatively slow to adapt to the demands of exercise and the time constant of the response to heavy exercise is about 25 s. The rate at which ATP can be resynthesized is aerobically much slower than that of anaerobic ATP resynthesis but oxidative metabolism can use carbohydrates, free fatty acids (FFAs) and [...]