Acute and Long-Term Effects of Stretching with Whole-Body Vibration on Young's Modulus of the Soleus Muscle Measured Using Shear Wave Elastography

Abstract

The effect of whole-body vibration (WBV) stretching on soleus (SOL) muscle stiffness remains unclear. Therefore, we aimed to investigate the acute and long-term effects of stretching with WBV on SOL muscle stiffness. This study employed a repeated-measures experimental design evaluating 20 healthy young males. SOL muscle stretching with WBV was performed for 5 min per day (1 min per set, five sets) over 4 weeks, for 4 days a week. Participants stretched the SOL muscle with ankle dorsiflexion in a loaded flexed knee position on a WBV device. Data were obtained to examine acute effects before stretching, immediately after stretching, and at 5, 10, 15, and 20 min. Moreover, data were obtained to examine the long-term effects before stretching, immediately after the completion of the 4-week stretching program, and at 2 and 4 weeks later. SOL muscle stiffness was measured using Young's modulus with shear wave elastography. The acute effect of SOL muscle stretching with WBV persisted for up to 20 min. Additionally, the long-term effect of stretching was better maintained than the acute effect, which was effective for up to 4 weeks (p < 0.001). Clinically, continuous stretching with WBV may be used to improve SOL muscle stiffness in rehabilitation programs.

Keywords: Young’s modulus; elastography; range of motion; soleus muscle; stiffness; stretching; whole-body vibration.

Figure 1

Illustration of the soleus (SOL) muscle stretching with the whole-body vibration (WBV) device. The participants stretched the SOL muscle during ankle dorsiflexion in the knee-flexed position under a load.

Figure 2

Illustration of the Young’s modulus measurement. (a) Posture during the measurement; (b) SWE images of the SOL muscle; (c) SWE images of the AT; (d) the colour scale.

Figure 3

Experimental protocols 1 (a) and 2 (b). Pre, before stretching with WBV; Post-0m, immediately after stretching with WBV; Post-5m, after 5 min of stretching with WBV; Post-10m, after 10 min of stretching with WBV; Post-15m, after 15 min of stretching with WBV; Post-20m, after 20 min of stretching with WBV; Post-0w, immediately after the completion of the 4-week stretching program; Post-2w, 2 weeks after the completion of the 4-week stretching program; Post-4w: 4 weeks after the completion of the 4-week stretching program.

Figure 4

Change over time in Young’s modulus of SOL muscle (a) and AT (b) before and after stretching with WBV in experiment 1. * Significant differences were detected using one-way repeated measures analysis of variance and Bonferroni post hoc test after stretching compared with before stretching (p < 0.05). Black lines within boxes and box borders indicate the median, 25th percentile, and 75th percentile, respectively.

Figure 5

Change over time in Young’s modulus of SOL muscle (a) and AT (b) before and after stretching with WBV in experiment 2. * Significant differences were detected using one-way repeated measures analysis of variance and Bonferroni post hoc test compared to before stretching (p < 0.05). Black lines within boxes and box borders indicate the median, 25th percentile, and 75th percentile.

Figure 6

Change over time in ankle dorsiflexion ROM before and after stretching with WBV in experiment 1 (a) and experiment 2 (b). * Significant differences were detected using one-way repeated measures analysis of variance and Bonferroni post hoc test compared to before stretching (p < 0.05). Black lines within boxes and box borders indicate the median, 25th percentile, and 75th percentile.