Inhibitory tendon-evoked reflex is attenuated in the torque-depressed isometric steady-state following active shortening

Abstract

Residual torque depression (rTD) is the reduction in steady-state isometric torque following an active shortening contraction when compared with an isometric contraction at the same muscle length and activation level. We have shown that spinal excitability increases in the rTD state, yet the mechanisms remains unknown. Percutaneous electrical tendon stimulation was used to induce tendon-evoked inhibitory reflexes. We demonstrated that in the rTD state, reduced torque contributes to a reduction in inhibitory afferent feedback, which indicates that the history-dependent properties of muscle can alter spinal excitability and the voluntary control of submaximal contractions through changes in peripheral afferent feedback. Novelty Residual force depression is a basic property of skeletal muscle, which can influence spinal and supraspinal excitability via inhibitory reflex activity. Residual force depression alters the voluntary control of force.