Immediate effects of localized vibration on flexibility: A randomized crossover trial

Localized vibration (LV) can enhance or replace stretching to increase flexibility. However, its effects on muscle flexibility remain unclear.

This study examines the immediate effects of short-duration LV training using a whole-body vibration device and conventional static stretching (SS) on lower limb flexibility in healthy individuals. This was achieved using muscle ultrasound (MUS), including three-dimensional shear wave elastography (3D-SWE).

This study employed a same-subject, repeated-measures design within a randomized crossover trial. Fourteen healthy participants were recruited and randomly assigned to receive either 1 min of LV to the bilateral crural muscles at 30 Hz and 3-mm amplitude or conventional SS. Each intervention was administered randomly on different days, with at least a one-day washout period. Each intervention was followed by a stand-and-reach test, and the medial and lateral heads of the gastrocnemius and soleus were examined using 3D-SWE and Doppler MUS. Each muscle was assigned a separate power Doppler subjective score (range, 0-3), and the power Doppler index (PDI) was calculated as the sum of the scores of all three muscles.

Both LV and SS resulted in decreased stand and reach test performance. However, the reduction was significantly lower with LV than SS. The PDI after LV was significantly higher than before LV (P < 0.01). Furthermore, SWE values at the medial/lateral head of the gastrocnemius was significantly lower after LV administration (P < 0.05), indicating a change in muscle elasticity.

SWE and Doppler MUS may be valuable for assessing muscle condition.