The Extended Time Course of Forearm Blood Flow Following a Maximal Bout of Exercise

Abstract

Chronic exercise is thought to improve endothelium-dependent vasodilation; however, studies evaluating endothelial dysfunction (ED) following an exercise training program lack a standardized time frame in which to measure vascular function (VF). Although most studies require subjects to abstain from exercise for 24 hours prior to any VF measures, no study to date has assessed VF longer than 24 hours after the cessation of 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 healthy male volunteers. METHODS: Twelve male subjects volunteered to participate. FBF was assessed before and during reactive hyperemia (RH). 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 baseline FBF and FBF during RH, was used as an indicator of VR. Blood samples were also obtained at each time point to evaluate the response of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-a), which are potential modifiers of VF. RESULTS: Baseline FBF and FBF during RH were significantly (P < 0.05) increased POST-E before returning to baseline values by POST-1. VR was significantly (P < 0.05) increased POST-E and was not significantly (P < 0.05) reduced until POST-48. Concentrations of IL-6 and TNF-a were unchanged in response to exercise. CONCLUSIONS: These results indicate that measurements used to verify improvements in VF following chronic exercise training should be employed more than 24 hours following a single bout of physical activity. Financial support was provided by the School of Education Research Initiation Awards Program at Virginia Commonwealth University