Accession Number:

ADP012448

Title:

Symptoms at Exhaustion from Uncompensable Exercise-Heat Stress

Descriptive Note:

Corporate Author:

ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA

Report Date:

2002-04-01

Pagination or Media Count:

6.0

Abstract:

Exhaustion occurs over a broad range of core temperatures during uncompensable exercise-heat stress. This study examined the symptoms at heat exhaustion and whether they differed among individuals terminating exercise at low vs. high core temperatures. Forty-seven healthy, heat-acclimated volunteers exercised to exhaustion during uncompensable heat stress on one or more occasions for a total of 133 trials. Mean core temperature - sd at exhaustion was 38.7 - 0.5 deg C range 37.4 to 39.8 deg C and was generally consistent within an individual. Volunteers stopped primarily due to ataxiadizziness 42, followed by physical exhaustion 25, headachenausea 17, dyspnea 12 and muscle cramps 4. Volunteers who terminated at lower core temperatures - 38.4 deg C were limited by physical exhaustion at a rate similar to those stopping at higher - 39.0 deg C core temperatures. However, those who stopped at lower core temperatures had a higher incidence of dyspnea and lower incidence of both ataxiadizziness and headachenausea when compared to volunteers terminating exercise at higher core temperatures Xsup 2 - 10.6 P 0.05. Therefore, heat intolerant persons were more likely to develop respiratory distress while heat tolerant persons were able to continue until cardiovascular and illness symptoms limited further effort. These data suggest that different physiological mechanisms contribute to the inter-subject variability in tolerance to uncompensable exercise-heat stress.

Subject Categories:

  • Medicine and Medical Research
  • Stress Physiology

Distribution Statement:

APPROVED FOR PUBLIC RELEASE