Forearm Blood Flow Response to an Acute Maximal Exercise Bout in Obese and Normal Weight Males

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One of the earliest sub-clinical stages associated with atherosclerosis is endothelial dysfunction (ED), which has been shown to predict future cardiovascular events. Chronic exercise is thought to improve endothelium-dependent vasodilation; however, few studies have evaluated the effects of acute exercise on vascular function (VF). In addition, no studies have compared VF responses in obese and non-obese individuals following acute exercise. PURPOSE:To evaluate VF, as determined by the assessment of forearm blood flow (FBF) and vascular reactivity (VR) before and up to 48 hours after a single bout of maximal exercise in obese and non-obese males. METHODS:Twelve obese (37.0 ± 1.1 kg/m2) and non-obese (21.9 ± 0.3 kg/m2) males volunteered to participate. FBF was assessed before (bFBF) and during reactive hyperemia (rhFBF). FBF measures were obtained prior to (PRE-E), immediately after (POST-E), and at 1 (POST-1), 2 (POST-2), 24 (POST-24), and 48 (POST-48) hours after exercise. Total excess flow, calculated as the difference between bFBF and rhFBF, was used as an indicator of VR. Blood samples were also obtained to evaluate the response of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α), which are potential modifiers of VF. RESULTS:Although there was no main effect for group, there was a significant (P < 0.05) main effect for time in bFBF, rhFBF, and VR. A group × time interaction was not significant for bFBF, rhFBF, and VR. A Dunnett's post-hoc revealed that POST-E values were significantly (P < 0.05) increased compared to PRE-E values for bFBF, rhFBF, and VR (mean difference±S.E.: 330.21±40.31; 530.60±81.61; 200.39±54.13 ml/100 ml/min × sec, respectively), before returning to PRE-E values by POST-1 (mean differences±S.E. - bFBF, rhFBF, and VR: 49.12±40.31, 111.03±81.61, 61.91±54.14 ml/100 ml/min × sec). Concentrations of IL-6 and TNF-α were unchanged in response to exercise in both groups. CONCLUSIONS:An acute bout of maximal exercise significantly increased forearm endothelium-dependent vasodilation in non-obese and obese males. Although VR prior to exercise is significantly correlated to percent body fat (r=0.508, P=0.011), excess adiposity does not contribute to impairment in forearm blood flow in otherwise healthy obese males following an acute bout of maximal exercise.