Differences in lifting strengths and postures between workers and novices among Taiwanese females

The effect of working experience on lifting strengths for males had been verified by Chen et al. (2011). This paper extends that study to compare the lifting strengths and the postures at various exertion heights between experienced workers and novices among Taiwanese females. Forty-six experienced workers and novices (23 of each) were recruited and were required to determine their static-lifting strengths under various height levels (10∼150 cm in increments of 10 cm) using two exertion methods (vertically upward lifting, VUL, and toward body lifting, TBL). Results showed that the VUL forces were much higher than the TBL at 15 height positions (p < 0.001). At lower heights (≤ 50 cm), workers' VUL forces were 5.67-7.40 kg higher than novices' and no differences were found in TBL at these heights (less than 2 kg). A reverse trend was found when lifting ranges were equal to or higher than 90 cm. Forces in all 30 task combinations showed no difference between the two groups at heights of 60-80 cm. Workers' strengths under all 15 lifting heights showed a relatively small fluctuation compared to novices' and they tended to adopt a fully squat and a more erect posture at lower and higher heights, respectively. The results suggested that lifting strength data generally collected on students should be carefully used in the task design.