Hand/tool interface effects on human torque capacity

Abstract

Forty student subjects, involving 20 males and 20 females, participated in this study. Four handle shapes (circular, triangular, square and hexagonal), seven handle sizes, (25.4, 31.8, 38.1, 44.5, 50.8, 57.2 and 63.5 mm), and five types of gloves (surgical, single cotton, double cottons, leather and rubber) were tested for their effects on maximum volitional torque exertion (MVTE) for supination. The results indicated that all the main effects were significant ( p < 0.001). Female MVTE is about 62% of male. Triangular shape was the most favorable, followed by square, hexagonal and circular shapes despite of the moment arms being in the ratios of 1.155, 1.414, 1 and 1. The gloved MVTEs are generally found to be superior to without gloves, about 10% to 30% increment. A positive correlation between supination MVTE and glove thickness is also found. For handle size effect, the larger the handle size is, the greater the MVTE is. Female has more effective torque exertion than that of male for handle size less than 44.5 mm (1.75″).