A-29 Thematic Poster - Vascular Control Wednesday, May 28, 2014, 9:30 AM - 11:30 AM Room: 102 B
African Americans (AA) have altered vascular function, even with a normal brachial blood pressure and beginning as early as 21 years of age. However, it is unknown if this impacts the blood flow response to exercise, or if there are changes with exercise training. We investigated baseline blood flow before and following exercise, and before and following training, in AA and Caucasians (CA).
PURPOSE: To determine if there are ethnic specific responses in forearm blood flow before and after a maximal exercise bout and following exercise training.
METHODS: Baseline and post acute peak exercise measurements were obtained in 75 sedentary subjects (38 AA and 37 CA, mean age=24 years). Resting forearm blood flow in addition to peak forearm blood flow and area under the curve (AUC) following reactive hyperemia measurements were assessed using strain gauge plethysmography (Hokanson) before and following VO2peak exercise. The 8 week endurance training program consisted of 30-60 min of endurance exercise at 60-90% of HRmax 3 times per week. Pre- and post-intervention values were compared between ethnicities using a repeated measures (2×2) ANOVA. When the interaction was significant, the responses were evaluated with paired samples t-tests within each group and independent t-tests between ethnicities.
RESULTS: AA had lower values of all measures compared to CA at all time points. Pre-training from rest to post acute exercise, AA vs CA had significantly lower values of FBF (presented in ml/100ml/min: 2.49 to 2.97 vs 3.15 to 3.50), peak FBF (18.59 to 19.28 vs 23.11 to 25.97) and AUC (58.20 to 62.65 vs 81.66 to 92.78), and this relationship did not change following 8 weeks of endurance training. In addition, AA had no increases in FBF, peak FBF or AUC following maximal exercise, in comparison to CA who had significant increases in AUC (both before and after training), peak FBF (before training), and FBF (after training) following maximal exercise.
CONCLUSIONS: AA have reduced forearm blood flow at rest and following exercise compared to CA. This racial difference is not improved by exercise training. This response could potentially be due to decreased nitric oxide bioavailability, which could be a factor in the endothelial dysfunction previously seen in AA.