The Association between Flow-Mediated Dilation and Oxidative Stress in Response to Acute Exercise

Abstract

A single bout of exercise has been used experimentally to investigate flow-mediated dilation (FMD) in response to acute physiological stress. We have previously observed the contribution of chronic physical activity (PA) in modulating the post exercise FMD response; however, the influence of oxidative stress has not been determined. Moreover, independent of PA status, some individuals exhibited a transient improvement in FMD (responder) while attenuation in FMD was observed in others (non-responder). PURPOSE: We sought to identify the association between oxidative stress and FMD in response to acute exercise in overweight men grouped by 1) PA status and 2) responders or non-responders. METHODS: FMD and TBARS were assessed in 14 overweight men at baseline and 1 hour following a single bout of moderate intensity (50% VO2peak) treadmill walking for 45 minutes. Of the 14 men, 7 were sedentary and 7 were active; 8 were non-responders and 6 were responders. RESULTS: No differences (p>0.05) in baseline FMD (8.2±1.2 vs. 6.1±1.2) or TBARS (17.4±2.5 vs. 17.8±3.1) was observed between the sedentary and active groups, respectively. Similar findings were observed between the responders and non-responders. An improvement in FMD following acute exercise was observed in both the active and responders groups, whereas a decrease in FMD was observed in the sedentary and non-responding groups. Controlling for baseline FMD, no differences in the TBARS response to acute exercise was observed between the sedentary (-1.2±1.0) and active group (-0.8±2.1); however, a significant (p=0.011) group × time interaction was observed such that the responders exhibited a reduction in TBARS (18.1±2.8 to 14.6±3.3), whereas an increase in TBARS (16.9±2.6 to 18.5±3.1) was observed in the non-responders. CONCLUSION: Oxidative stress in response to acute exercise does not appear to contribute to the FMD response in overweight active and sedentary men; however, when stratifying the same subjects into responders and non-responders, the FMD response appears to be associated with changes in oxidative stress. Supported in part by Gatorade Sports Science Institute and Indiana University HPER Research Grants.