Assessment of Biological Reaction to Whole Body Vibration Training by Evaluating Changes in Salivary Components and Cutaneous Blood Flow

Abstract

Aim: Whole body vibration (WBV) is thought to improve blood flow and autonomic balance and thereby induce a relaxation effect, which suggests its use for stress management. However, the relaxation effect of WBV training has not been objectively evaluated thus far. The purpose of this study was to determine the biological response to WBV training by measuring peripheral blood flow and salivary components using non-invasive techniques. Methods: Participants included 10 healthy volunteers (7 men, 3 women; mean age 33.8 ± 2.3) who provided oral consent and served as their own control. Each participant performed 15 types of stretching exercises for 10.5 min on the Power Plate? and cutaneous blood flow and salivary components were measured before and after the exercise. One week later, all participants performed the same exercise regimen for 10.5 min on a non-vibratory plate, and blood flow measurement and salivary tests were performed in a similar manner. Cutaneous blood flow was measured in the 4th digit for 1 min using the laser speckle flowgraphy. Saliva samples were evaluated for cortisol levels and α-amylase activity. To determine the effects of stretching exercises on the Power Plate? vs a non-vibratory plate, the differences in pre- and post-exercise peripheral blood flow, salivary cortisol levels, and salivary α-amylase activity were statistically evaluated by the t-test. Results: Mean blood flow before and after the exercise on the Power Plate? was 122.0 ± 54.2 and 156.7 ± 51.2, respectively; on a non-vibratory plate, blood flow was 136.6 ± 47.9 and 146.3 ± 38.3, respectively. The differences in pre-exercise and post-exercise values of the two training methods were not significant (p = 0.215). Mean cortisol levels before and after the exercise on the Power Plate? were 266.6 ± 125 and 204.9 ± 61.6, respectively; on a non-vibratory plate, the levels were 439.0 ± 121.7 and 425.8 ± 118.8, respectively. The differences in pre-exercise and post-exercise values of the two training methods were not significant (p = 0.384). Mean α-amylase activity before and after the exercise on the Power Plate? was 3.74 ± 2.89 and 5.40 ± 3.76, respectively; on a non-vibratory plate, the activity was 3.95 ± 2.23 and 3.28 ± 1.73. The differences in pre-exercise and post-exercise values of the two training methods were not significant (p = 0.115). Conclusion: Our results showed that a brief WBV training increased peripheral blood flow, reduced cortisol levels, and increased α-amylase activity. WBV appears to regulate autonomic activity, in particular, suppress sympathetic activity and improve bodily functions. Thus WBV exercise may be conductive for stress management, but further investigation is warranted to determine the optimal duration of WBV training for stress relief.