Abstract

Physical exercise significantly affects the homeostasis due to the increased demand for energy in working muscles. In prolonged exercises, proteins, besides lipids and carbohydrates, are an important source of energy. Muscle work results in inhibiting protein synthesis, and the thus increased free amino acid pool enters the energy-rendering processes. This may be accompanied by a degradation of intracellular proteins in order to maintain the free amino acid pool, and by a flux of free amino acids from other tissues and their utilization in working muscles. The catabolic processes are thus intensified, e.g. in the gastro-intestinal tract, liver, kidneys, lymphatic tissue, and in non-active muscles. The regulation of those processes is effected by glucocorticoids. In the phase of recovery following prolonged exercises the cellular proteins are being gradually resynthetized, the process being dependent on the exercise performed. Following endurance exercises an increased protein synthesis takes place in mitochondria of ST muscle fibers, i.e. in those engaged in exercise. The resynthesis of all proteins requires the promoting action of androgens, but glucocorticoids also contribute to this process, e.g. by inducing the glycogen synthase activity. Verf.-Referat