Abstract

We report the signs and symptoms (SAS) of heat exhaustion observed in 14 healthy, unacclimatized males during 8 days of heat acclimation (HA) by intermittent treadmill running in an environmental chamber (41.2 +- 0.5 degr. C dry bulb, 39.0 +- 1.7 RH). Twelve out of 14 subjects (85.7) experienced one or more SAS (e.g., dizziness, chills, abdominal cramps, vomiting). SAS occurred in 20 out of 112 trials (17.8). HA was important in reducing the incidence of SAS (days 1-4, 23 SAS, days 5-8, 10 SAS). SAS were not more prevalent at high exercise intensities; the greatest number of SAS occurred at 50-69 VO2max. Correlation coefficients (r2) of relationships between the number of SAS and physical characteristics were: age, 0.31; height, 0.16; mass, 0.03; surface area, 0.00; surface area/mass, 0.10; VO2max, 0.01 (all p > .05). It was concluded that SAS were not related to physical characteristics. Furthermore, physiological measurements taken at the time of premature termination of trials (39.5 degr. C rectal temperature) indicated that it was unlikely that subjects perceived hyperthermia as a threat to their well-being. Verf.-Referat