Psychophysical determination of load carrying capacity for a 1-h work period by Chinese males.

This study used the psychophysical approach to examine the effects of container width, the presence or absence of container handles, and different load-carrying frequencies and distances on the maximum acceptable weight carried and the resulting response (heart rate and rating of perceived exertion) by well-conditioned males for a 1-h work period. After training, 12 male subjects performed a load-carrying task at knuckle height. Each subject performed 30 different carrying combinations. The conditions examined were container width, from 15.2 to 55.9 cm; carrying frequency, from 1 carry to 5 carries/min; and carrying distance from 1 to 6 m. The results were compared with prior studies and led to the following conclusions: (1) the use of container handles leads to the subjects carrying a significantly higher maximum acceptable weight than when containers do not have handles, which differs from the results of a previous study by Morrissey and Liou; (2) there were significant reductions in the maximum acceptable carrying weight with increases in container width, frequency and distance; (3) the presence or absence of container handles, different frequencies and load-carrying distances had significant effects on heart rate, although the effect of container width was not significant. In addition, the various frequencies and distances for load carrying had significant interaction effects on heart rate; (4) the effects of various frequencies and load-carrying distances on the rating of perceived exertion were statistically significant. The most stressed body parts were the wrists and arms.