Increased sensitivity of forearm skin vasodilation at a given increase in esophageal temperature after aerobic training was caused by increased cardiac stroke volume

Abstract

We examined the hypothesis that the enhanced sensitivity of an increase in forearm skin vascular conductance at a given increase in esophageal temperature (ΔFVC/ΔT_es) during exercise after aerobic training would be caused by concomitant increases in blood volume (BV) and cardiac stroke volume (SV). Twelve male subjects (age, 21.3±0.7 (SE) yr; Vo_2peak, 58.0±0.8 ml·min⁻¹·kg⁻¹) exercised on a cycle ergometer at 60% Vo_2peak, 1 hr·day⁻¹, at 30°C of room temperature and 50% of relative humidity for 10 days. Before and after training, ΔFVC/ΔT_es was determined by having subjects perform 20-min exercise (EX) at 70% of pre-training Vo_2peak in the same environment. After training, BV at rest increased by 5.1±0.9 ml·kg⁻¹ (P<0.001) which was accompanied by an increase in SV of 0.31±0.05 ml·kg⁻¹ (N=10, P<0.001) at 10 min of EX. ΔFVC/ΔT_es determined after the onset of forearm skin vasodilation was 18.5±3.3 units·°C⁻¹ before training, increased to 31.6±4.2 units·°C⁻¹ after training (P<0.0001). The increase in ΔFVC/ΔT_es for individuals was correlated with the increase in SV at 10 min of EX (N=10, r=0.83, P<0.005), which was also correlated with BV (N=10, r=0.68, P<0.001). Thus, the increase in ΔFVC/ΔT_es after aerobic training may be enhanced by increased SV partially due to increased BV. [Jpn J Physiol 54 Suppl:S238 (2004)]