Researchers have found that the maximum fingertip pinch strength is least while the forearm is pronated, maximum key pinch strength is least while the forearm is supinated, and maximum three-jaw chuck pinch strength is unaffected by forearm position.
One hundred thirty five healthy adults were tested for the three types of maximum pinch strength with the forearm in a pronated, neutral and supinated position. The data was collected by three trained raters with subjects placed in specific upper extremity postures for the strength measurements. Findings were stratified for age, handedness, and gender.
The average, maximum, male fingertip pinch strength with the forearm in neutral position was 15.46 pounds for the right hand and 14.95 pounds for the left hand. The respective female strength measurement was 10.79 pounds for the right hand and 10.03 pounds for the left hand.
The average, maximum, male key pinch strength with the forearm in neutral position was 23.16 pounds for the right hand and 22.36 pounds for the left hand. The respective female strength measurement was 16.03 pounds for the right hand and 14.72 pounds for the left hand.
The average, maximum, male three-jaw pinch strength with the forearm in neutral position was 20.67 pounds for the right hand and 20.14 pounds for the left hand. The respective female strength measurement was 15.26 pounds for the right hand and 14.0 pounds for the left hand.
Stegink Jansen C.W., Kocian Simper V., Stuart H.G., and Pinkerton H.M. “Measurement of Maximum Voluntary Pinch Strength: Effects of Forearm Position and Outcome Score.” Journal of Hand Therapy 16: 326-336, 2003.
This article originally appeared in The Ergonomics Report™ on 2004-04-01.