| Keywords |
Cold intervention; Heat acclimation; Heat tolerance; Time memory; Acclimation program |
| Abstract |
Heat exposures induce heat acclimation but it needs to investigate whether or not heat acclimation occurs when the heat exposure is conducted along with cold exposure. We hypothesized that short-term heat acclimation through the cold-interrupted heat exposure would occur even though the heat exposure is intermittently interrupted by cold exposure.
The heat exposure program consisted of a 2-h treadmill exercise in an environment (30oC in Ta and 60%RH in air humidity, afternoon session) for 14 consecutive days. A 2-hour cold exposure was conducted in a cold environment (10oC in Ta and 40%RH in air humidity, morning session) before heat exposure program each day. Eight male subjects participated in a heat tolerance test (afternoon session) before (PRE) and after (POST) the 14-day cold-interrupted heat exposure program. Both changes of mean skin and mean body temperatures were lower in POST than those in PRE (P<0.05) while no statistical difference was found for change in rectal temperature between PRE and POST. There were no statistical differences in heart rate, systolic and diastolic blood pressures, and local sweat rates between PRE and POST. Subjects felt less hot, less uncomfortable, and less wet on their hands in POST when compared to those in PRE during the heat tolerance test (P<0.05). These results showed the possibility that heat acclimation was interfered with repeated cold exposures. |