Effect of muscle stretching on tension development and mechanical threshold during contractures.

Abstract

STRETCHING a muscle over its resting length produces changes in its performance during activation. These changes can be reflected as an increment in the peak tension and in duration of the twitch or both1–8; in the lower rate of stimulation necessary to produce maximal tetanic tension8, 9; in the tension developed by skinned fibres10 or in the ability to produce more work after the stretch2. It has been found that stretching produces an increase in oxygen consumption11 or heat production12, and several explanations have been given. It has been proposed, for example, that the stretch effect is due to increased activity of the Na pump13, or to an increase in the Na+ concentration in the cytoplasm12 or simply due to a positive feedback effect5, 8.