Continuous vs. intermittent work with Canadian Forces NBC clothing.Aviat Space Environ Med. 1993 Jul; 64(7):595-8.AS
This study examined the benefits of work and rest schedules on soldiers' work tolerance (WTT) while wearing various levels of nuclear, biological and chemical (NBC) defence protective clothing in a warm environment (30 degrees C and 50% R.H.). Eight unacclimatized males were 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). Subjects were tested wearing three levels of clothing protection: combat clothing (L); combats and a semi-permeable NBC overgarment with the hood down (M); combats and NBC overgarment, gloves, boots and respirator (H). For each clothing configuration, subjects were evaluated using both a "continuous" exercise protocol and an intermittent work and rest schedule. WTT was defined as 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. Assuming a resting VO2 of 4 ml.kg-1 x min-1 an average metabolic rate was calculated for all trials. A decreasing hyperbolic function described the relationship between WTT and metabolic rate for M and H. These relationships facilitate quantification of appropriate work and rest schedules if the metabolic rate of a task is known.