Effects of interdigital spacing, wrist position, forearm position, grip span, and gender on static grip strength

To analyze the effects of factors which may decrement static grip strength, a study was performed using 20 subjects (10 males and 10 females). Three levels of interdigital spacing were examined: 0, 4, and 8 mm to correspond to bare hand, a thermal/spectra knit layered glove, and a chemical glove. Three wrist positions (neutral, 45 degree extension, and 45 degree flexion) and three forearm positions (neutral, full supination, and full pronation), as well as two levels of grip spacing (6.1 and 7.4 cm on the hand dynamometer) were varied in the study. Thus, each subject performed 54 trials, which were presented in random order. The results indicate that the following were significant main effects: gender, grip span, forearm position, wrist position, and interdigital spacing. As expected, males exerted 63.7% more strength, on average, than females. Also, full pronation had a significantly lower mean grasp strength than either neutral or full supination. The 8 mm spacing differed significantly from both 0 and 4 mm spacing and both 4 and 8 mm spacing had a lower mean grasp strength than 0 mm. Also, the 7.4 cm position on the hand dynamometer had significantly lower mean grasp strength as compared with the 6.1 cm position. Wrist position affected mean grasp strength as well; with a neutral wrist position, the strength was significantly higher than either flexed or extended, with a greater decrement from flexion than extension.