Purpose: To examine the time course (immediate, 10, 20, and 30 min) for the acute effects of 2, 4, and 8 min of passive stretching (PS) on isometric peak torque (PT), percent voluntary activation (%VA), EMG amplitude, peak twitch torque (PTT), rate of twitch torque development (RTD), and range of motion (ROM) of the plantarflexors. Methods: Thirteen volunteers (mean ± SD age, 22 ± 3 yr) participated in four randomly ordered experimental trials: control (CON) with no stretching, 2 min (PS 2), 4 min (PS 4), and 8 min (PS 8) of PS. Testing was conducted before (pre), immediately after (post), and at 10, 20, and 30 min poststretching. The PS trials involved varied repetitions of 30-s passive stretches, whereas the CON trial included 15 min of resting. PT, %VA, EMG amplitude, PTT, and RTD were assessed during the twitch interpolation technique, whereas ROM was quantified as the maximum tolerable angle of passive dorsiflexion. Results: PT decreased (P ≤ 0.05) immediately after all conditions [CON (4%), PS 2 (2%), PS 4 (4%), and PS 8 (6%)] but returned to baseline at 10, 20, and 30 min poststretching. %VA and EMG amplitude were unaltered (P > 0.05) after all conditions. PTT and RTD decreased (P ≤ 0.05) immediately after the PS 4 (7%) and the PS 8 (6%) conditions only; however, these changes were not sufficient to alter voluntary force production. There were also increases (P ≤ 0.05) in ROM after the PS 2 (8%), the PS 4 (14%), and the PS 8 (13%) conditions that returned to baseline after 10 min. Conclusion: Practical durations of stretching (2, 4, or 8 min) of the plantarflexors did not decrease isometric PT compared with the CON but caused temporary improvements in the ROM, thereby questioning the overall detrimental influence of PS on performance.
- Muscle activation
- Range of motion
- Stretching-induced force deficit
ASJC Scopus subject areas
- Orthopedics and Sports Medicine
- Physical Therapy, Sports Therapy and Rehabilitation