Muscle Blood Flow Responses to Dynamic Handgrip Exercise in Young Obese Adults

Abstract

INTRODUCTION: Exercise intolerance is a hallmark characteristic of obesity, which may be related to an impaired ability to appropriately increase blood flow to the contracting muscles. Limited evidence suggests that steady-state vasodilator responses to dynamic forearm exercise are preserved or even increased in young obese humans compared with lean peers, but this topic still remains poorly understood. PURPOSE: To evaluate exercise-induced changes in hemodynamics in young obese adults compared with lean adults. METHODS: Thirteen lean (female=6; 26±1 yrs; 22.4±0.5 kg/m2) and 14 obese adults (female=7; 27±1 yrs; 32.6±0.6 kg/m2) performed 2-min of dynamic forearm exercise at 15 and 30% of maximal voluntary contraction (1-s contraction: 2-s relaxation). Ultrasonography [brachial diameter, forearm blood flow (FBF), forearm vascular conductance (FVC)], and beat-to-beat hemodynamics [mean arterial pressure (MAP), heart rate (HR), stroke index (SI), systemic vascular resistance index (SVRI), cardiac index (CI), systemic arterial compliance index (SACI)] were collected. FBF and FVC were normalized to lean forearm mass, and hemodynamics were indexed to body surface area. RESULTS: There were no group differences in any variable at baseline. Brachial artery diameter, FBF, FVC, and HR increased from baseline at 15% and 30% of MVC similarly in both groups (P<0.05). There was an interation for SVRI (P<0.05), where SVRI decreased from baseline at 15% and 30% MVC only in the lean group (P<0.05). CONCLUSION: Although young obese adults did not exhibit an impairement in exercise-induced increases in blood flow, systemic vascular resistance did not decrease with exercise in obese adults. Future studies in an older population may reveal more consistent obesity-related impairments, whereas our current cohort is young and lack comorbidities.Table: No title available.Data are mean±SE. *P<0.05, time effect. ?P<0.05, interaction. aP<0.05, different from baseline.