Abstract
BACKGROUND: Stretching is believed to decrease muscle strength. The aim of this paper was to examine the time course (immediate, and 10- and 20-minutes post-stretching) for the effects of 2, 4, and 8 minutes of static-stretching (SS) on the isometric maximum voluntary contraction force (MVCF) of hamstring muscles with a pretest-post-test experiment design.
METHODS: A total of 14 subjects with a mean age of 25 years participated in three experimental trials on three different days. Day I for static stretching for 2 minutes (SS2), day II for 4 minutes (SS4), and day III for 8 minutes (SS8). Testing was conducted before (pre), immediately after (post), and at 10- and 20-minutes post-stretching. MVCF was measured using the strain gauze as the main outcome measure.
RESULTS: MVCF increased with SS2 at 0 minutes (1.31%), 10 minutes (3.4%), and 20 minutes (4.1%) postintervention. MVCF increased with SS4 at 0 minutes (1.13%), 10 minutes (9.6%) and 20 minutes (7.1%) postintervention. MVCF decreased with SS8 at 0 minutes (2.9%), but increased at 10 minutes (1.86%) and 20 minutes (0.99%) postintervention. All these changes were not statistically significant (P>0.05).
CONCLUSIONS: In hamstring stretching, 2, 4 and 8 minutes increased MVCF, but results were not statistically significant. Thus, 2 to 8 minutes long-duration stretching exercises could safely be performed before a strength-training session.