1) I agree with everyone here about the need to streamline the process. Once screen for entry, etc...
2) What does each term mean? I know most of them, but whats an "exercise group?" People who don't work out a lot may not know what other things mean. E.g. reps = repetitions. Put something like "number of repetitions" instead.
3) A lot of workout programs are something like: Run a little for 4 weeks. Run a medium amount for 4 weeks. Run a large amount for 4 weeks.
If thats how I'm doing things, I don't want to enter 12 weeks worth on info, I want to enter 3 weeks and have each one repeated. I'm not 100% sure how I would redesign the interface, for this, you can try a few things out...
4) Why are the numbers in drop downs? To me, thats very unnatural (others might disagree).
5) Having it so that anyone can edit and delete a workout could be a bit chaotic.
Edit: 6) One more. After I create a workout, the link at the bottom says "Index." What does that mean? A button that says "Done" or something would be more clear.