Heat Intolerance, Heat Exhaustion Monitored: A Case Report.

A 32 year-old male S.H. monitored during an 8-day heat acclimation HA investigation, unexpectedly exhibited heat intolerance and heat exhaustion. Thirteen other males completed HA without indications of either heat intolerance or heat exhaustion. Because S.H. responded normally to HA on days 1 - 4, the intervention of an unknown host factor on days 5- 8 was suggested. S.H.s heat exhaustion episode day 8 was apparently forewarned by loss of body weight and increased heart rate, skin temperature days 5 - 8 and rectal temperature days 7 - 8 during daily 90 min trials. His symptoms indicated classical salt depletion heat exhaustion, but the calculated salt deficit was mild. Post-heat exhaustion serum enzyme levels were either normal or acutely elevated. Blood beta-endorphin and cortisol levels were 6 times and 2 times greater than control values, respectively. This case report is unique because physiological measurements and blood analyses were performed before, during, and after heat intolerance and heat exhaustion. Keywords Exercise Sodium Potassium Plasma volume Sweat Serum enzymes Beta-endorphin Aldosterone Plasma renin Cortisol.