[Skeletal muscle reaction to the loading limit. III. Changes in the contractile apparatus]

A description is given of the changes in the contractile apparatus of the skeletal muscle following extreme long-term exercise. In detail, they include Z-stripe dehiscences, myofibril disintegrations and destructions of single sarcomer . These findings are known from myopathology . A characteristic feature is their subsarcolemmic localisation. The pathogenesis is discussed. In connection with the alterations of the sarcolemma and the mitochondria as well as the increased endo- and exocytosis of the muscle fibre, the cause is seen in a local intracellular catabolism. At the same time, the possible importance to the effluence of enzymes, especially of creatine phosphokinase, is pointed out.