Self-Paced Heat Acclimation Procedures

• Main Authors: Armstrong,Lawrence E, Hubbard,Roger W, DeLuca,Jane P, Christensen,Elaine L
• Format: Report
• Language: English
• Subjects: ACCLIMATIZATION; ARMY PERSONNEL; ARMY TRAINING; AS879; BODY TEMPERATURE; CASUALTIES; ENDURANCE(PHYSIOLOGY); EXPOSURE(PHYSIOLOGY); HEART RATE; HEAT STRESS(PHYSIOLOGY); HEAT TOLERANCE; ILLNESS; MILITARY EXERCISES; PE62777A; PHYSICAL FITNESS; RECRUITS; Rectal temperature; Stress Physiology; SWEAT GLANDS

The purpose of this investigation was to evaluate thh effectiveness of self-paced heat acclimation (SPHA) procedures. fourteen males performed 100 nmin of intermittent exercise during 9 SPHA work-rest cycles, on eight days. Exercise consisted of 8.279 P or - 0.527 to 9.799 + or - 0.433 km of treadmill running per day. SPHA trials were effective in improving heat tolerance in that significant (p .05) reductions were observed (day 1 vs day 8) in final heart rate (HR), Delta HR, final rectal temperatures (Tre), Delta Tre, final mean weighted skin temperature (Tsk), and Delta Tsk. Resting plasma volume expanded significantly (p . 05) from day 1 to day 4, but sweat rate was unchanged. Group mean exercise intensities and ratings of perceived exertion were not statistically different from days 2 - 7, let the number of trials terminate because subjects exceeded HR and Tre safety limits (22 out of 112 trials) declined during heat acclimation (days 1-4 = 16, days 5-8 = 6). Symptoms of heat illness (piloerection, chills, dizziness, vomiting) were observed in 16.1% of all trials; 11 out of 14 subjects (78.6%) experienced one or more or these symptoms during SPHA trials.