Signs and Symptoms of Heat Exhaustion During Strenuous Heat Acclimation Exercise

摘要

This investigation reports the heat exhaustion signs and symptoms (SAS) which fourteen healthy, unacclimatized males experienced during 8 days of heat acclimation (HA) in an environmental chamber (41.2 + or - 0.5 C db, 39.0 + or - 1.7 % RH). Daily HA trials consisted intensities of 63.0 + or - 2.8 to 71.8 + or - 2.9 (range: 51 - 95) %VO2max. Typical physicological adaptations to heat occured. Mean day 1 vs day 8 values were: final HR = 169 + or - 3 vs 144 + or - 5 beats min-1, final Tre = 39.19 + or - 0.10 vs 38.55 + or - 0.17 C, final Tsk = 37.56 + or - 0.21 vs 36.52 + or - 0.26 C, %PV = 7.33 + or - 0.89 vs 5.85 + or - 1.31. Mean entering body weight was stable from day 1 to day 8, except that subject N lost 5.44 kg from day 5 to day 8. Subject N was one of four subjects who exhibited a lack of physiological adaptations in HR, Tre, Tsk and % delta PV. 12 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%). SAS were not more prevalent at high exercise intensities; the greatest number of SAS occurred at 50 - 69 % VO2 max. Keywords: maximal aerobic capacity; heart rate; rectal temperature; plasma volume; running.