Handing It to the Wrist for Forceful Grip
For most people, the hands and fingers are an important part of everyday life. Daily activities require the use of finger strength and coordination. Some jobs really depend on the strength of the fingers and hands to complete work tasks.

Grip strength has been measured and studied closely. Matching a worker's strength with the strength needed for job tasks is important. Static measures for grip and pinch strength are commonly used. This means the strength is tested in one position without moving the wrist or arm.

But what about jobs that require a certain amount of grip strength while moving? Does changing the wrist position change finger and hand strength? It makes sense that a different wrist position would change the force of each finger.

A study has been done using nine healthy adult men. All the men were right-handed. Their grip strength was measured while moving the wrist through its full range of motion. The wrist moved forward and back in flexion and extension. Motion also included side to side movement called radial and ulnar deviation.

A special device was used to measure the force (strength) of each individual finger. The strength of the fingers does depend on the position of the wrist. In general, the fingers are strongest when the wrist is extended and moved toward the ring finger. Strength didn't seem to vary or fluctuate much in this position. The fingers did show differences in strength when the wrist was bent.

Fingers work together to share the workload when the hand is gripping an object. To get the best grip with the strongest force, extend the wrist back and angle the wrist out slightly. Avoid extreme wrist positions.
References
Zong-Ming Li, PhD. The Influence of Wrist Position on Individual Finger Forces During Forceful Grip. In The Journal of Hand Surgery. September 2002. Vol. 27A. No. 5. Pp. 886-896.