Maximal and graded effort perception by young females in stoop lifting, hand grip and finger pinch activity with comparisons to males

Ten normal young adult females (mean age 26.8 years, mean weight 50.9 kg, mean height 165.9 cm) performed maximal and subjectively graded exertions of the stoop lift, hand grip, and finger pinch. The levels of graded exertion required were 80%, 60%, 40% and 20% of maximal voluntary contraction (MVC). The sequences of all conditions were fully randomized. Each of the randomized conditions was tried three times in succession. The entire experiment was carried out on four different days at the same time of the day on Monday, Wednesday, Friday of one week and Friday of the next week. The data obtained were subjected to descriptive and statistical analysis with t-test, analysis of variance, and correlation and regression. There were significant differences in the effort produced in three different activities (p < 0.01). The levels of exertion from 20% to 80% were all significantly different from each other (p < 0.01). However, there were no significant differences between the three trials of any given condition and the exertions produced on four different days. The 80% and 60% of exertions were overestimated and 20% was underestimated compared to the objective values based on MVC (p < 0.01). At 40% effort there was no significant difference between the objective level of exertion and subjectively gauged and produced effort for all three activities. The reliability of perception among the female subjects was similar for finger pinch, hand grip, and stoop lift activities.