Diet and Whole-body Vibration Training on Cardiovascular and Autonomic Function

Overview

Obesity is a major risk factor for premature arterial abnormalities including high blood pressure and increased stiffness. Previous studies have shown that weight loss via lifestyle modifications is associated with a decrease in large artery (aorta) stiffness. However, along with decreases in fat mass, hypocaloric diet reduces muscle mass. Whole body vibration results in similar increases in muscle mass and strength than those observed after resistance exercise and is feasible for special populations such as the obese and the elderly. The investigators hypothesis is that weight loss via diet combined with whole body vibration training would additively reduce arterial stiffness and blood pressure in obese women. The investigators also hypothesize that the improved arterial function with weight loss would be associated with beneficial changes in the main mechanisms involved in BP regulation.

The purpose of the study is to examine the effects of 12 weeks of whole body vibration training (WBVT) and diet on arterial function, autonomic function, and body composition in obese women. Specific aims of the study are to: To evaluate the extent to which diet and (WBVT) will improve body composition assessed by changes in fat mass and lean mass using dual-energy x-ray absorptiometry and waist circumference. To investigate that combined diet and (WBVT) are more efficacious than either treatment alone in ameliorating cardiovascular disease risk factors by assessing arterial stiffness (aortic, systemic, and leg), aortic BP and wave reflection, and autonomic function (heart rate variability, vascular sympathetic activity \[low-frequency power of systolic BP variability\], and baroreflex sensitivity). Flow mediated dilation and circulating levels of adipocytokines (adiponectin and leptin) and endothelial-derived vasodilators (NO metabolites \[NOx\], 6-keto PGFIa, insulin, and ghrelin) and vasoconstrictors (endothelin-1 \[ET-1\],8-iso PGF2a,vascular endothelium growth factor \[VGEF\]) will be assessed as secondary outcome variables.