Sweat distribution before and after repeated heat exposure

We investigated the impact of short-term, moderate humidity heat acclimation upon sweat distribution. Eight males completed six daily heat exposures [cycling: ambient temperature 39.5 (0.2)°C, relative humidity 59.2 (0.8)%], during which auditory canal temperature (T _ac) was maintained 1.4°C above pre-exposure levels for 70 min by manipulating the work rate. On days 1 and 6, T _ac and local sweat rates (m˙ _sw: eight sites) were monitored. The pre-exposure, resting T _ac and the T _ac sweat threshold decreased from day 1 to day 6 [36.83 (0.05)°C vs 36.62 (0.05)°C, and 36.90 (0.05)°C vs 36.75 (0.05)°C, respectively; both P<0.05]. However, the sweat-onset time, sweat sensitivity (Δm˙ _sw/ΔT _ac) and established m˙ _sw were unaltered (P > 0.05). There was also no evidence of a post-acclimation redistribution in established m˙ _sw between the eight skin regions, though both the sweat sensitivity and established m˙ _sw for the forehead and hand were significantly greater than at the remaining sites (P<0.05). It is concluded that the 5-day heat acclimation regimen provided only a minimal stimulus for sudomotor adaptation. Accepted: 3 March 1997