ADJUSTMENT PERIOD EFFECTS ON PSYCHOPHYSICAL LIFTING CAPACITY FOR FEMALE PARTICIPANTS

ABSTRACT

The effect of adjustment period on psychophysically lifting capacity for males had been verified by Wu and Chen [32]. This paper extends Wu and Chen's study to investigate the adjustment periods effects of females and to examine the difference between genders. Eight female participates were recruited to perform 16 different combinations of lifting tasks involving four adjustment periods (20, 30, 40, and 50 min) and four lifting frequencies (1, 2, 4, and 6 lifts/min) from the floor to knuckle height for 8-h work shift. The adjustment period effects on the MAWL, and RPE values were significant. The MAWL decreased significantly as adjustment period increased. The participants lifted 4.2, 7.5 and 11.9% less MAWL when the lifting task was performed at 30, 40, and 50 min adjustment periods, respectively. The RPE value increased as the adjustment period increased. In addition, this paper verified that the effect of gender differences for the adjustment period and lifting frequency was not significant. Generally, this study shows that the MAWLs was overestimated by about 3.6% and 8.1% when the adjustment periods were decreased from 40-min to 30-min and 20-min, respectively.

Keywords:

• psychophysics
• adjustment periods
• manual materials handling
• maximum acceptable weight of lift