| Recently, researchers have demonstrated that Whole Body Vibration results in significant increases in skin blood flow. No study has determined if there is an optimal frequency or duration for optimizing this response. In addition, there is no known mechanism for the increase in skin blood flow. It is hypothesized that nitric oxide (NO) is responsible for the increase in skin blood flow due to its ability to vasodilate the smooth muscle in response to shear stress. Therefore, the purpose of this research was to determine the optimal frequency and duration of vibration and determine if NO is the mechanism for the vibration-induced skin blood flow increases. In this study three populations were examined: young adults (age = 45 years, n=10) and adults with type II diabetes (age = >45 years, n=10). Vibration was provided by a Power Plate set at either 30 or 50 Hz and skin blood flow was assessed by a laser Doppler. The role of NO was determined by using venous blood samples, which were tested for nitric oxide metabolites by a process called chemiluminescence. In addition, NO production was blocked with L-NAME to see if the skin blood flow response would be blocked. By the fourth minute 30 and 50 Hz vibration significantly increased skin blood flow and peak flows were obtained by the fifth minute. Although there was no significant difference between 30 and 50 Hz, 50 Hz was able to increase skin blood flow more rapidly and keep it elevated throughout 15 minutes of recovery. In the young adults, NO production (544%) and skin blood flow (569%) increased significantly (p<0.05) after 5 minutes of vibration and then decreased significantly after 5 minutes of recovery. When NO production was blocked, there was a 43% (p<0.05) decrease in vibration-induced skin blood flow. Skin blood flow and NO production also increased significantly (p<0.05) in older adults (SBF, 461% NO, 374%) and adults with diabetes (SBF, 223% NO, 263). However, skin blood flow in the healthy older adults increased significantly more than in the adults with diabetes (p=0.003). In conclusion, vibration is capable of increasing skin blood flow in young adults, older adults and adults with type II diabetes. It appears that NO is the mechanism for vibration-induced increases in skin blood flow in the forearm. |
