Maximum acceptable weight of lift by Chinese experienced male manual handlers

This study uses a psychophysical methodology to determine the maximum acceptable weight of lift (MAWL) for 13 Chinese experienced male subjects, and examines the effects of variations in box size (including 300, 450 and 600 mm, sagittal distance from body) and lifting frequency (including one-time-maximum, 1, 4 and 6 lifts/min) on the MAWL, and the resulting responses [heart rate and rating of perceived exertion (RPE)]. The results are compared with prior studies and lead to the following conclusions: (1) Increases in both the box size and lifting frequency induced a significant decrease in MAWL, and a significant increase in RPE and heart rate. However, overall RPE ratings were not increased significantly with box size. (2) For Chinese inexperienced male subjects, the overall MAWL and heart rate were approximately 85% and 91% of their experienced male counterparts, respectively. The decrement in MAWL with Occidental subjects was about the same for both experienced and inexperienced groups; (3) The average MAWL values of Chinese subjects were smaller than those of Occidental subjects, and the average rate of decrease in MAWL with increasing of lifting frequency for the Chinese subjects was much sharper than in Occidental subjects; (4) There was no significant difference in overall heart rate and RPE ratings between the Chinese subjects and Occidental subjects. However, the body part RPE ratings were different from the previous studies. The present study found the most stressed body parts were the back and wrist, which may have been caused by the height of the table (760 mm) and the smaller body size of the Chinese subjects compared with the Occidental subjects.