No Evidence of Racial Differences in Endothelial Function and Exercise Blood Flow in Young, Healthy Males Following Acute Antioxidant Supplementation

Abstract

This study investigated the effects of acute antioxidant supplementation on endothelial function, exercise blood flow and oxidative stress biomarkers in 9 young African American compared to 10 Caucasian males (25.7±1.2 years). We hypothesized that African American males would have lower exercise blood flow and endothelial responsiveness compared to Caucasian males, and these responses would be improved following antioxidant supplementation. Ultrasonography was used to measure blood flow during handgrip exercise. Endothelial function was assessed using flow-mediated dilation, and lipid peroxidation was assessed by measuring levels of malondialdehyde-thiobarbituric acid reactive substances. African American males exhibited lower endothelial function than Caucasians at baseline (8.3±1.7 vs. 12.2±1.7%) and the difference was ameliorated with antioxidant supplementation (10.7±1.9% vs. 10.8±1.8%), but the interaction was not significant (p=0.10). There were no significant changes in malondialdehyde-thiobarbituric acid reactive substances following antioxidant supplementation. There was a significant increase in brachial blood flow and forearm vascular conductance with exercise but no differences with antioxidant supplementation. There were no group differences in exercise responses and no differences with antioxidant supplementation, suggesting a lack of influence of oxidative stress during exercise in this cohort.

Attenuated forearm vascular conductance responses to rhythmic handgrip in young African-American compared with Caucasian-American men

“…Our major novel finding is that healthy young AA men present an attenuated elevation in FVC and FBF during moderate-and high-intensity rhythmic handgrip exercise compared with healthy young CA men. These findings extend previous studies (15,16) in which there were no significant differences in FVC and FBF between AA and CA individuals at lower handgrip intensities (10% and 20% MVC). Additionally, our study confirmed similar FBF responses between AA and CA individuals at low-intensity handgrip (15% MVC), which is within the range of handgrip intensities previously investigated (15,16).…”

“…These findings extend previous studies (15,16) in which there were no significant differences in FVC and FBF between AA and CA individuals at lower handgrip intensities (10% and 20% MVC). Additionally, our study confirmed similar FBF responses between AA and CA individuals at low-intensity handgrip (15% MVC), which is within the range of handgrip intensities previously investigated (15,16). Exercise elicits both sympathetic vasoconstriction and local vasodilation in contracting muscle.…”

“…Although racial differences in vascular responses to exercise have been investigated, the number of studies performed is minimal and equivocal results have been reported. Specifically, one study showed no significant difference between CA and AA individuals in the elevation of forearm blood flow (FBF) during rhythmic handgrip (16), whereas another study reported a lower FBF response in AA individuals (15). The reason for these discrepancies is unclear.…”

Cardiac Oxidative Stress and the Therapeutic Approaches to the Intake of Antioxidant Supplements and Physical Activity

“…Exerciseinduced changes in blood flow, arterial dilation, or vasodilatory responses can provide information about the cardiovascular function and endothelial dysfunction that is not visible at rest. In exercise-induced vasodilation, NO plays a key role [84], and higher free radicals and oxidative stress can also cause reductions in exercise-induced vasodilation because decreased vasodilation might reduce perfusion during exercise [85]. It is important to figure out how to increase vasodilation with exercise.…”

“…It is important to figure out how to increase vasodilation with exercise. It is also unclear how antioxidant supplementation would alter genetic variations in exercise or the possibility of increased exercise vasodilation and blood flow [84,85]. Exhausting activities, extended workouts, overtraining syndrome, and overcoming limitations as a phase of overtraining syndrome's early beginnings cause a significant oxidative stress response.…”