Internal mechanics of the musculature, theoretical study of normal and atrophic muscles (author's transl)

Abstract

The article demonstrates, taking muscles of feathery structure as an example, that loss of contractile muscular mass by one-half would correspond to one-half of the power at the tendon if the muscle fibres are arranged in parallel. In the force-distance profile changes after the muscular mass has been reduced to one-half; the muscles with a more pronounced feathery structure will possess a little more than one-half of the original force in the state of greater muscle fibre length. On the other hand, if an atrophic muscle of this type, i.e. of feathery structure, is shortened, there is a considerable loss of power which goes far beyond the loss of muscular mass. This change in the force-distance profile of atrophic feathery muscles can be ascribed to the change in the geometric arrangement of the individual fibres, and to the maximum capacity of extension of the muscle fibres to twice their original length. This performance will explain at least in part the inhibition of the final stretching of the knee joint in case of atrophy of the vastus muscles, the feathery structure of which differs individually.