Subjective estimates of one-handed carrying tasks

In this study, ten male and five female subjects, ranging between 21 and 23 years in age and in excellent physical health, voluntarily participated. Four different shapes of containers, 8.5 and 12.3 litres in capacity, were used to carry loads for distances of 100, 200, and 300 ft (30.48, 60.96, and 91.44 m, respectively). Individuals first subjectively estimated how much weight they could carry in a given type of container for the required distance and then verified it by actual carrying. The preferred (stronger) hand was used to hold the containers. In addition to the weight acceptable for comfortable carrying, pulse rate and ratings of perceived exertion (RPE) of the arm and whole body were also used as response measures. Results indicated that subjects could quite accurately estimate the amount of weight they could carry comfortably in one hand. RPE for one-handed carrying tasks was not one-tenth of the pulse rate as is the case for whole body tasks. The average pulse rate was 100 beats/min for the weights selected. Shape of the containers significantly influenced the amount of weight subjects were willing to carry in one hand. The acceptable amount of weight decreased with distance, but was found to increase with volume.