STRETCHING REDUCES FORCE PRODUCTION IN THE QUADRICEPS

Power, K., Behm, D., Cahill, F., Carroll, M., Young, W. (2004). An acute bout of static stretching: effects on force and jumping performance. Medicine and Science in Sports and Exercise, 36, 1389-1396.

This study examined whether a static stretching routine decreased isometric force, muscle activation, and jump power while improving range of motion. It also attempted to compare the duration of the dependent variable changes with the duration of the change in range of motion. Ss (N = 12) were tested pre- and post-static stretching (at 30, 60, 90, and 120 minutes) of the quadriceps and plantar flexors or a similar period of no-stretch (control). Measurements during isometric contractions included maximal voluntary force, evoked contractile properties (peak twitch and tetanus), surface integrated electromyographic activity of the agonist and antagonistic muscle groups, and muscle inactivation as measured by the interpolated twitch technique. Vertical jump measurements included unilateral concentric-only (no countermovement) jump height as well as drop jump height and contact time. Range of motion associated with seated hip flexion, prone hip extension, and plantar flexion-dorsiflexion was also recorded.

After static stretching, there were significant decreases in maximal voluntary force and muscle inactivation in the quadriceps. Force remained significantly decreased for 120 min (10.4%), paralleling significant percentage increases (6%) in sit and reach range of motion at 120 minutes. There were no significant changes in jump performance or plantar flexion measures after stretching.

Implication. Reductions in quadriceps isometric force suggest an association between stretch-induced changes in muscle range of motion and isometric force output.

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