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Scheduling cycles of work for hot ambient conditions.
Ergonomics 1979 Apr; 22(4):427-439
Six male college students were monitored for changes in rectal (Tre) and mean skin (T) temperatures, heart rate (HR), and sweat production and evaporation to determine optimal work and rest periods based on muscular work and heat stress. Exercise cardiograms were recorded and maximal oxygen uptake was measured during a progressive treadmill stress test under warm and humid and dry and hot ambient conditions. Resting responses were tested under the same conditions as work, and under neutral ambient conditions. HR and Tre responses were similar for consecutive work and rest cycles under neutral conditions, and continuously increased from cycle to cycle when work and rest were under the same warm and humid condition. Both responses were reduced with rest at neutral ambience. Responses were less strained in hot and dry ambience in general and reduced further with rest in the neutral condition. When the metabolic demand of work was close to the maximal aerobic capacity, the allowable work period was shorter and the rest requirement was longer. The author concludes that the design of cyclic work can be based on the cumulative circulatory strain of the work load and heat stresses, and HR can be used as a strain indicator. Resting periods must be scheduled for cooler neutral ambient conditions when work is performed under humid ambient conditions.
NIOSH-Publication; NIOSH-Grant; Grants-other; Research-laboratories; Scientific-personnel; Work-time-standards; Work-scheduling; Work-planning; Work-intervals; Heat-exposure; Working-load; Stress-relaxation-tests; Rest-periods; Humans
Eliezer Kamon, The Noll Laboratory for Human Performance Research, Pennsylvania State University, University Park, Pa. 16802, U.S.A.
Issue of Publication
Other Occupational Concerns; Grants-other
Pennsylvania State University Park, University Park, Pennsylvania
Page last reviewed: November 6, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division