Influence of temperature and metabolic rate on work performance with Canadian Forces NBC clothing.

This study examined the effects of environmental temperature and metabolic 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 metabolic 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. (cool) or 30 degrees C, 50% R.H. (warm). Subjects were tested wearing three levels of clothing protection: combat clothing (L); combats and a semi-permeable NBC overgarment (M); combats and NBC overgarment, gloves, boots and respiratory (H). WTT was the time until rectal temperature (Tre) reached 39.3 degrees C, heart rate reached 95% maximum, dizziness 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 significantly 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 warm 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.(ABSTRACT TRUNCATED AT 250 WORDS)