Physiological Responses to Intermittent Exercise as Modified by Heat Stress and Protective Clothing
Abstract
Time-weighted averaging is a method employed in heat stress analyses to consolidate the rate of heat production (M) from complex intermittent exercise patterns into a single continuous level of heat production. Physiological responses during intermittent and continuous exercise were studied in 4 subjects exposed to heat stress in which evaporation was either free or severely restricted. Intermittent work consisted of repeated 10 min exercise/ rest patterns. Continuous work was at the time weighted average of intermittent exercise. When heat stress was uncompensable, intermittent work induced more physiological strain than continuous work: endurance time was 14 min les (p<.05) , core temperature at 60 min was 0.40 C higher (p<.05), and the rate of core temperature rise was 33% greater. The difference in the rate of heat storage was not satisfactorily explained by a discrepancy in average M or in the calculated rate of surface heat loss. Alternatively, results may be explained by interruptions in the rate of heat transport via the cutaneous circulation. These interruptions may be associated with postural and workload transitions. While the mechanisms are not totally understood, it is clear that application of the time-weighted averaging method should be applied with discretion.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1991
- Accession Number
- ADA237447
Entities
People
- Kenneth K.
- Richard R. Gonzalez
Organizations
- United States Army Research Institute of Environmental Medicine