Psychophysically determined 1-h load carrying capacity of Chinese females

Abstract

This study used psychophysical approach to examine the effects of container width, carrying rate, and distance on the maximum acceptable weight carried (MAWC) and the resulting responses (heart rate and rating of perceived exertion) to a 1-h work period of carrying tasks. After training, 12 Chinese females performed 27 different load-carrying tasks in random order. The conditions examined were container width (24.7, 35.6 and 46.5 cm), carrying rate (22.5, 36.0 and 49.5 s per carry), and distance (2.1, 3.5 and 4.9 m per carry). The results obtained lead to the following conclusions: (1) The container width significantly affected the MAWC, heart rates and overall RPE values. Although the heart rates increased with the container width, the MAWC and the overall RPE values did not decrease with the container width. (2) The carrying rate had significant effects on the MAWC, heart rate and overall RPE values. The MAWC declined with an increase in the carrying rate. However, the heart rate and RPE values increased with the carrying rate. (3) The carrying distance significantly affected the MAWC, heart rate, but had no significant effect on the overall RPE values. The MAWC decreased with an increase in the carrying distance and the heart rate increased with the carrying distance. (4) Both the carrying rate with container width and the carrying rate with distance had significant interaction effects on the MAWC. (5) The mean carrying heart rate of the subjects was approximately 53.6% of their maximum heart rates and the mean predicted carrying oxygen consumption was about 29.4% of VO 2 max. The most stressed body parts were the legs (RPE=13.5). (6) The MAWCs of Chinese females were 61% of the MAWC for Chinese males. Relevance to industry The results of this work can be used to design safe manual carrying tasks for Chinese females.