I did a study on motor unit muscle recruitment and elbow angle effect on strength/motor unit recruitment while gripping something (in this experiment's case it was 3 grippers). I'm not going to post the graphs unless someone really wants me to, but we had about 15 people do the test, which was 3 grippers at 3 different elbow angles (30 degrees, 90 degrees, and 180 degrees.. so each gripper at each angle, then move up in gripper strength, repeat, etc.) and the results were interesting: people recruited more motor units in their forearm at 30 degrees (arm near shoulder) than at 90 degrees (2nd place) or 180 degrees (arm stretched out). Also, predictably, people recruited 250% more motor units at a higher resistance level (IronMind #1) than the lowest level (random store brand gripper "Medium"). It was a pretty interesting study, and although there are a variety of factors which could have played a role in the results, it would be wise for someone to try and position their arm in different ways before seein what kind of arm position works best for their grip.