Effects of Muscle-Tendon Interaction on Force Development in Human Skeletal Muscle in Vivo

Abstract

In human skeletal muscles in vivo, there is a lengthwise interaction between muscle fibers and tendinous tissues due to slackness and elastic property of tendinous tissues (muscle-tendon interaction). This study aimed to investigate the effects of the muscle-tendon interaction on 1) time to force onset and 2) time-course of force during force development, through measurements of fascicle behavior using the Motion-mode and Brightness-mode ultrasolography. The muscle-tendon interaction affected over-40% of the time from stimulus to force production, and the following time-course alteration of force generating capacities as a function of slackness and operating range in non-linear length-force relationship of tendinous tissues. These would influence joint angle-dependence of electro mechanical delay and time-course change of fascicle force.