In athletics, the amount of force an athlete can produce when he or she clenches their hands around an object can affect the outcome of an event. Training the hands is as significant as other exercises and should not be neglected or limited.
As a coach, trainer or athlete it is important to know the posture that allows the greatest output of hand strength to enhance development.
Grip-strength is highest when the elbow is fully extended. This can easily be seen by taking measurements with the elbow positioned at 0 degrees, 45 degrees, 90 degrees and 135 degrees of flexion and grasping as hard as possible.

Posture And the Grip
Not only does arm flexion affect grip power, but standing posture generally has a greater outcome than when sitting. The Pendulum Grip Pro is an upright gripping device that allows for arm extension, as well as standing so the athlete can choose the appropriate and optimal posture to maximize development.

Pendulum Power Grip Pro