Abstract
The main objectives of this study were: (1) to determine the effects of work-rest ratios on physiological responses for manual lifting tasks performed over different levels of loads and frequencies of lift for a height of lift of 30" from floor level while keeping task duration and work output as constant, (2) to study for a given work period the effect of varied rest periods on energy consumption, (3) to study for a given rest period the effect of varied work periods on energy consumption, and (4) to investigate, for a given work-rest ratio, the effect of short work short rest periods versus long work long rest periods on energy consumption.In order to achieve the objectives of this research, an eloborate experiment was conducted. The independent variables studied were: frequency of lift and work-rest schedules. The response variables for this experiment were: heart rate, oxygen consumption, and minute ventilation.Eight male subjects, 20 to 34 years of age, participated in this experiment. A randomized complete block design with factorial treatment combinations was used. Each subject performed, in a random order, 34 treatment combinations for this experiment. All subjects underwent a training program before the data collection began.The results of this experiment were analyzed using the analysis of variance technique. By manipulating frequency of lift, load, and work-rest ratios whether there could be any significant difference in physiological strain and energy cost for this lifting task with fixed work output for a fixed time at a fixed height of 30 inches above floor level, was tested. It was identified from this experiment that the least work-rest schedule was found to be 12 minutes work followed by 6 minutes rest which was based on the average minimum energy consumption among all the treatments across all the subjects.