Mechanical Properties of Shortened Skeletal Muscle

Abstract

Several features of the mechanical response of shortened muscle were investigated in rat gastrocnemii subjected to shortening by tetanus toxin injection, by tenotomy and by immobilization for 14 days. Total twitch times of toxin treated and immobilized muscles were reduced because of accelerated relaxation. Immobilized muscle showed no change in total twitch time. Tetanus-twitch ratios were increased by tetanus toxin injection and immobilization induced shortening, but decreased in tenotomized muscle. The optimal stimulation frequency appeared to be slightly lower in experimental muscles than in contralateral control muscles.