Resting brachial artery shear rate is associated with exercise habituation in middle aged and older adults

Abstract

Hemodynamic shear stress, a frictional force of blood on the arterial wall, decreases with aging. The reduction in shear stress involved in development and progression of vascular endothelial dysfunction, a risk factor of cardiovascular disease. Habitual exercise is an effective strategy to improve vascular endothelial function. However, the effect of habitual exercise on the resting shear stress is unknown. The aim of this study was to determine whether brachial artery shear stress correlates with exercise habituation in middle aged and older adults.A total of 112 healthy middle aged and older adults (50–76 years) participated in this study. We measured peak and mean brachial artery shear rates, as indices of shear stress, at rest. Daily step counts and maximum oxygen consumption (VO2max) were measured as an index of exercise habituation. Subjects were divided into the inactive group (< 7500 steps/day) and the active group (蠅 7500 steps/day).VO2max was significantly higher in the active group than in the inactive group (P < 0.01). Peak shear rate and mean shear rate in the active group were significantly higher than in the inactive group (P < 0.01 and P < 0.05). VO2max correlated significantly with peak (r = 0.362, P < 0.01) and mean shear rates (r = 0.302, P < 0.05). These associations were remained significant even when adjusted for age.These results suggest that habitual exercise may increase resting brachial artery shear stress in middle‐aged and older adults.