Role of physical work capacity and load weight on psychophysical lift ratings

This study examined the effect of load weight, and physical work capacity (PWC) on psychophysical lift ratings of 33 men and 58 women. Each subject lifted seven boxes that ranged in weight from 6.8 kg to 40.9 kg and rated each lift with Borg's CR-10 scale. The lift components were a Vertical distance of the hands to the floor of 53 cm, and a vertical lift distance of 48 cm. Subject PWC was assessed two ways: arm, shoulder, torso, and leg isometric strength; and fat-free weight determined from skinfold fat, Physical work capacity was significantly correlated with CR-10 ratings for each of the seven lifts and the women's ratings were significantly higher than those of the men. Multiple regression showed that the CR-10 ratings were a function of lift weight and PWC (R = 0.87). Logistic regression quantified PWC levels for psychophysically acceptable lift loads defined by CR-10 ratings less than or equal to 7. These results showed that lift load and PWC are independent factors of psychophysical lift ratings.