1986 Volume 24 Issue 2 Pages 75-86
The purpose of this study was to apply psychophysical principles to establish the optimum work rate during load transportation on the head and by yoke. The metabolic and perceptual responses of 10 male students of average aerobic capacity (3.67±0.77 ιmin-1) were monitored while carrying external loads (11.6, 16.1 and 20.6 kg) at varying speeds (3.2, 4.4 and 5.6 km•hr-1) on a level motor-driven treadmill using the headpack and the transverse yoke modes of load carriage. The physiological and perceptual responses for the 2 modes of load car-riage were not statistically different (p>0.05). As such, the values for the 2 modes were averaged. In order to identify the optimum rate of work, the mean oxygen uptake (VO2), local ratings of perceived exertion and the overall body exertion were plotted against the walking speeds. The optimum work rate estimated by physiological (40% VO2max) criteria was higher than that by perceptual (RPE=12 on Borg's 15-point category scale) criteria. The findings suggest the need to take into consideration the subjective feelings of exertion in addition to the work rate conditions that elicit 40 VO2max when prescribing standardsf or external load transportation.