I tried the closed fist drill for a few lengths in a pool. I alternated between closed fist drill and normal swimming as fast as possible, with full rest between. However, the times were the same between closed fist and normal, and when using closed fist, both stroke rate and stroke per length increased slightly, resulting in the same time.
How should I interpret the numbers?
Stroke rate and strokes per length increased, which should mean you were working harder for the same speed. Closed fist is less resistance so there can be a little less effort there, but your regular stroke should still be faster at AFAP speeds. I suspect your form is better with closed fist. One reason to do closed fist is to work on EVF. If your EVF is better closed fist than regular swimming that would explain the discrepancy.
I see swimmers using paddles that are too big for them, or the swim gloves, who start dropping their elbow so that their form is worse. That may be analogous to your problem.
Stroke rate and strokes per length increased, which should mean you were working harder for the same speed. Closed fist is less resistance so there can be a little less effort there, but your regular stroke should still be faster at AFAP speeds. I suspect your form is better with closed fist. One reason to do closed fist is to work on EVF. If your EVF is better closed fist than regular swimming that would explain the discrepancy.
I see swimmers using paddles that are too big for them, or the swim gloves, who start dropping their elbow so that their form is worse. That may be analogous to your problem.
