Superior skin microvascular vasodilator function in trained versus untrained male adolescents

In youth, remedial benefits of exercise training on conduit vessel endothelium-dependent vasodilator function have recently been documented, however it remains to be established whether exercise training also impacts on endothelium-dependent vasodilator function at the microvascular level in youth who are free from chronic disease.

PURPOSE: To determine whether a group of trained youth have superior skin microvascular endothelium-dependent vasodilator function compared to untrained healthy controls.

METHODS: Forearm skin blood flow (SkBF) was assessed in 17 trained (14.6 ± 0.2 yrs, VO2peak: 54.9 ± 1.5 mL.kg-1.min-1, Self-assessed Tanner stage 2 - 4) and 9 untrained (15.6 ± 0.2 yrs, VO2peak: 43.1 ± 1.7 mL.kg-1.min-1, Tanner stage 2 - 4) male adolescents using laser Doppler flowmetry at baseline (basal SkBF) and following physiological provocation. Endothelium-dependent vasodilator function of the skin microcirculation was assessed physiologically through local heating to 44°C for 30 minutes (maximal SkBF) and post-occlusive reactive hyperaemia (PORH), which involved SkBF assessment following 3 minutes of arterial occlusion. Cutaneous vascular conductance (CVC) (SkBF/MAP) was calculated at baseline and at maximal thermal flux.

RESULTS: Maximal SkBF was significantly higher in trained versus untrained youth (Trained: 281.7 ± 29.2 vs Untrained: 204.2 ± 22.6 PU, p=0.04). Maximal flux during PORH was also significantly higher in trained compared to untrained youth (Trained: 50.4 ± 5.2 vs Untrained: 35.2 ± 5.0 PU, p=0.04). Trained youth also demonstrated significantly greater basal SkBF and basal CVC (basal SkBF Trained: 11.2 ± 0.9 vs Untrained: 8.6 ± 1.0 PU, p=0.03; basal CVC Trained: 0.12 ± 0.01 vs Untrained 0.08 ± 0.01 PU/mmHg, p=0.04) and possessed superior maximal CVC (Trained: 3.00 ± 0.34 vs 2.02 ± 0.23 PU/mmHg, p=0.03) compared to their untrained counterparts.

CONCLUSION: Skin microvascular endothelium-dependent vasodilator function is significantly enhanced in healthy, trained male adolescents. This may have implications for the prevention of endothelial dysfunction with aging and chronic diseases such as diabetes.