Leone, D. G., Pezarat-Correia, P., Valamatos, M. J., & Fernandes, O. (2009). Acute effects of a low-stretching dynamic protocol in the upper body force production. ACSM 56th Annual Meeting, Seattle, Washington. Presentation number 1657.

This study investigated the acute effect of a low-stretching dynamic protocol on maximal isometric force, time to maximal isometric force, rate of force development, and EMG amplitude of the main agonist muscles acting on the bench press exercise. Ss (N = 20) were randomly allocated into no-stretch and dynamic-stretch groups. The maximal voluntary isometric contraction on the bench press exercise was measured before and after (immediately, 10, 20, and 30 minutes) each treatment. The average amplitudes of the surface EMG of the pectoralis major and the long and lateral heads of the triceps brachii were measured during maximal voluntary isometric contraction.

There was a significant decrease (~4%) in the maximal isometric force from the pre to the post-treatment in the dynamic group. There were no significant differences in the time to maximal isometric force, rate of force development, and EMG amplitude of the three investigated muscles from pre to post-stretching. No significant differences were found in the control group in the force or in the EMG parameters between pre and post-treatment. Force did not remain significantly decreased for 30 minutes in both groups.

Implication. Dynamic stretching adversely affects maximal isometric arm strength for a brief period. The reduction in performance does not appear to be caused by the reduction of muscle activation.

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