[Destructive changes in the muscles of sportsmen during dynamic cyclic exercise of different intensities].

An electron microscopic investigation of bioptates from the external vast femoral muscle in sportsmen performing cyclic activity of various power has been performed: sprinters to middle distances, short-distance skaters and rowing-sportsmen--work in the zone of submaximal power; skaters to the distance of 3,000-10,000 m and racing skiers to the distance of 5-10 km--work of great power; racing skiers to long distances--prolonged work of moderate power. When working in the zone of the submaximal power, the signs of destruction of contracting structures in the muscle fiber are poorly manifested. When the work is of greater power and of greater duration with moderate power, necrotized fibers are found in the sportsmen's muscles. In muscle fibers with sublethal lesions, increasing autophagic processes are noted. The destructive changes of various degree of manifestation, revealed in muscle fibers predetermine the programme of adaptive changes in the muscles of the sportsmen specialized in different sports.