Hand grip performance with the bare hand in the extravehicular activity globe

Abstract

Astronauts have complained of difficulty in grasping tools, hand fatigue, and hand/forearm pain during extravehicular activities. This study was conducted to examine hand grip performance with a bare hand and in a spacesuit glove at two different pressures, with three hand positions and two elbow positions. Sixteen subjects, selected from the suited-subject pool at the Johnson Space Center, gripped a hand dynamometer encased in a vacuum chamber designed to simulate the operating pressures in space. The results for the bare hand condition showed a significant effect for hand position and a significant elbow/hand interaction. The spacesuit glove at operating pressure was responsible for an average 42% grip strength decrement from the bare hand condition. A new procedure for determining hand size from projected hand surface area revealed that bare and gloved-hand grip strength was highly correlated with hand size, as were body weight, height, and forearm circumference.