Effects of glove, orientation, pressure, load, and handle on submaximal grasp force

While the use of gloves often aid in the safety of completing tasks, and in some cases can even increase performance, as occurs with torquing tasks, there is most often a trade off between increased safety and performance capability when donning gloves. This is especially true in the microgravity EVA environment. The objectives of the present program of research were to examine grasp force at maximal and submaximal exertions, and to address the possibility of a relationship tactility and grasp force. A series of studies were conducted to examine grasp force at the hand/handle interface under a variety of performance conditions. Experiment 1 was conducted to examine the effect of glove type, pressure differential, and lifted load on grasp force at submaximal exertions. Experiment 2 also examined the effect of glove type and lifted load on submaximal grasp force. In addition, handle size and handle orientation were also examined. Experiment 3 was an examination of the effect of glove type, load lifted, handle size and handle orientation on maximal grasp force. Findings indicated that grasp force was effected by frictional and load tactile feedback. Consistent with published evidence, there was a strong glove effect at maximal exertions. However, the glove effect was marginal at submaximal exertions. This suggests that the neuro-muscular mechanisms utilized during maximal exertions are differentially applied and/or different from those used during submaximal or `just holding' types of exertion. The implications for the designer are discussed.