title: Aerobic training and cutaneous vasodilation in young and older men.
abstract: 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 were 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 (VO2 max) on a cycle ergometer for 60 min at 36 degrees C. Cutaneous 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 flowmetry. Forearm vascular conductance was calculated as forearm blood flow (venous occlusion plethysmography) divided by mean arterial pressure. Esophageal and skin temperatures were recorded. Only aerobic training (functionally defined a priori as a 5% or greater increase in VO2 max) produced a decrease in the mean body temperature threshold for increasing forearm vascular conductance (36.89 +/- 0.08 to 36.63 +/- 0.08 degrees C, P < 0.003) and cutaneous vascular conductance (36.91 +/- 0.08 to 36.65 +/- 0.08 degrees C, P < 0.004). Similar thresholds between control and bretylium-treated sites indicated that the decrease was mediated through the active vasodilator system. This shift was more pronounced in the older men who presented greater training-induced increases in VO2 max than did the young men (22 and 9%, respectively). In summary, older men improved their SkBF response to exercise-heat stress through the effect of aerobic training on the cutaneous vasodilator system.
authors.affiliation: Noll Physiological Research Center, The Pennsylvania State University, University Park, Pennsylvania 16802-6900, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Thomas
authors.forename: J M
authors.initials: JM
authors.lastname: Pierzga
authors.forename: W L
authors.initials: WL
authors.lastname: Kenney
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001823:Body Composition / Q000502:physiology; D001831:Body Temperature / Q000502:physiology; D001950:Bretylium Tosylate; D015444:Exercise / Q000502:physiology*; D018882:Heat Stress Disorders / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology; D012867:Skin / Q000098:blood supply*; D013565:Sympatholytics; D014661:Vasoconstriction / Q000502:physiology; D014664:Vasodilation / Q000502:physiology*
chemical_list: D013565:Sympatholytics; D001950:Bretylium Tosylate