Exercise-heat acclimation in young and older trained cyclists

Objectives: The purpose of this study was to investigate the effect of age on the capacity to acclimatise to exercise-heat stress. This study hypothesised that age would not affect body temperature and heat loss effector responses to short-term exercise-heat acclimation in trained subjects. Design: Seven young subjects (19-32 years) were matched with 7 older subjects (50-63 years). Subjects were highly trained but not specifically heat acclimated when they exercised for 60 min at 70%VO2max in hot-dry (35 degrees C, 40%RH) and thermoneutral (20 degrees C, 40%RH) conditions, pre and post 6 days of exercise-heat acclimation (70%VO2max, 35 degrees C, 40%RH). Methods: Rectal temperature (T-r), skin temperature (T-sk), heart rate (HR), cutaneous vascular conductance (CVC) and whole body sweat loss (M-sw) were measured during each testing session and T-r and HR were measured during each acclimation session. Results: T-r, T-sk, %HRmax, CVC and M-sw were similar across age groups both pre and post heat acclimation. Following heat acclimation relative decreases and increases in T-r and M-sw, respectively, were similar in both subject groups. There was a significant reduction in heart rate (%HRmax) and increase in final CVC following the acclimation programme in the young group (all p < 0.05) but not the older group. Conclusions: When comparing young and older well trained adults we found age affected the cardiovascular adaptation but not body temperature or whole body sweat loss to exercise-heat acclimation. These data suggest age does not affect the capacity to acclimatise to exercise-heat stress in highly trained adults undergoing short-term heat acclimation. (C) 2013 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.