William A. Sands

Acute effects of vibration-assisted stretching are more evident in the non-dominant limb

Abstract The aim of this study was to investigate the acute effects of a vibration-assisted static stretching intervention on enhancing split range of motion in gymnasts matched on initial range of motion. Twenty-two female artistic gymnasts (mean age 13.8 years, s=2.3) matched for age (±6 months) and competitive level were randomly assigned to a static stretching intervention with or without simultaneous vibration. The test consisted of adopting a forward split position with the rear leg bent to 90° and held vertically against a matted block while the pelvis remained perpendicular to the lines of the two legs. The gymnast was instructed to descend into the lowest split position of her comfortable pain tolerance. Positions were videotaped and digitized creating an angle between the split legs. The stretching intervention consisted of a forward split position with emphasis on the front leg hamstring muscle group, followed by a forward lunge position with emphasis on the rear leg quadriceps muscle group. In each position, four sets of stretches were completed each of 10 s duration with 5 s of rest between sets. The experimental group performed stretches with the vibration device turned on while the control group performed the same stretches with the vibration device turned off. A pre-test was performed to obtain baseline scores with the post-test following immediately after the vibration or control stretching intervention. Difference scores were calculated between the pre-test and post-test for each gymnast, and compared between groups using independent t-tests. Results showed significant post-test differences between the vibration and non-vibration groups (mean difference 12.2±5.2° vibration vs. 7.8±3.5° non-vibration, P=0.030) in the non-dominant limb, but no significant differences in the dominant limb (mean difference 10.2±4.3° vibration vs. 7.9±6.1° non-vibration, P=0.32). Vibration-assisted static stretching may provide a greater stimulus for range of motion improvements in limbs that have a lower initial level of flexibility.