Aerobic training and cutaneous vasodilation in young and older men

To determine the effect and underlying mechanisms of exercise training and the influence of age on the skin blood flow (SkBF) response to exercise in a hot environment, 22 young (Y; 18-30 yr) and 21 older (O; 61-78 yr) men we re assigned to 16 wk of aerobic (A; YA, n = 8; OA, n = 11), resistance (R; YR, n = 7; OR, n = 3), or no training (C; YC, n = 7; OC, n = 7). Before and after treatment, subjects exercised at 60% of maximum oxygen consumption ( (V)over dotO(2max)) On a cycle ergometer for 60 min at 36 degrees C. Cutane ous vascular conductance? defined as SkBF divided by mean arterial pressure , was monitored at control (vasoconstriction intact) and bretylium-treated (vasoconstriction blocked) sites on the forearm using laser-Doppler flowmet ry. Forearm vascular conductance was calculated as forearm blood flow (veno us occlusion plethysmography) divided by mean arterial pressure. Esophageal and skin temperatures were recorded. Only aerobic training (functionally d efined a priori as a 5% or greater increase in (V)O-2max) produced a decrea se in the mean body temperature threshold for increasing forearm vascular c onductance (36.89 +/- 0.08 to 36.63 +/- 0.08 degrees C, P < 0.003) and cuta neous vascular conductance (36.91 +/- 0.08 to 36.65 +/- 0.08 degrees C, P < 0.004). Similar thresholds between control and bretylium-treated sites ind icated that the decrease was mediated through the active vasodilator system . This shift was more pronounced in the older men who presented greater tra ining-induced increases in (V)over dotO(2max), than did the young men (22 a nd 9%, respectively). In summary, older men improved their SkBF response to exercise-heat stress through the effect of aerobic training on the cutaneo us vasodilator system.