INFLUENCE OF TEMPERATURE AND METABOLIC-RATE ON WORK PERFORMANCE WITH CANADIAN FORCES NBC CLOTHING

This study examined the effects of environmental temperature and metab olic rate on soldiers' work tolerance time (WTT) while wearing various levels of nuclear, biological, and chemical (NBC) defence protective clothing. There were 23 unacclimatized males (23 +/- 3 years, 76 +/- 8 kg, 1.77 +/- 0.08 m) assigned to exercise at either a light (walking 1.11 m . s-1 0% grade, alternating with lifting 10 kg) or heavy metabo lic rate (walking 1.33 m . s-1 7.5% grade, alternating with lifting 20 kg) in an environmental chamber at either 18-degrees-C, 50% R.H. (coo l) or 30-degrees-C, 50% R.H. (warm). Subjects were tested wearing thre e levels of clothing protection: combat clothing (L); combats and a se mi-permeable NBC overgarment (M); combats and NBC overgarment, gloves, boots and respiratory (H). WIT was the time until rectal temperature (Tre) reached 39.3-degrees-C, heart rate reached 95% maximum, dizzines s or nausea precluded further exercise, or 5 h had elapsed. During the light and cool trials (N = 5), wearing M or H did not impair WTT (277 +/- 47 min). For the light and warm experiments (N = 6), WTT was sign ificantly impaired with H (82.7 +/- 10.6 min). With the heavy and cool condition (N = 6), WTT was reduced with M (240.5 +/- 73.8 min) and H (56.7 +/- 17.9 min). Finally, during the heavy and worm trials (N = 6) , WTT was progressively impaired for L (172.5 +/- 52.8 min), M (65.8 /- 18.2 min), and H (34.0 +/- 9.7 min) levels of protection. These dat a quantify the impairment in physical work performance associated with wearing the Canadian forces NBC protective clothing as the metabolic rate and/or the environmental temperature is increased.