A Bicep Curl Output Challenge.
Here we use a dynamometer to measure elbow flexion (biceps etc) output, with differing grips and wrist positions. As you can see, when we take the wrist out of the equation completely, we get a far higher strength reading. The implications are: If your goal is to maximally challenge elbow flexors then it might be useful to add in some exercises that exclude the wrist from time to time. This will allow you to generate greater force and lift heavier loads.