We have both the Cycle-core and the Cycle-Zen workouts.

They are basically a nice addition to trainer work, but if you are looking for core conditioning DVD's, there are much better and more comprehensive choices out there. That said, these videos do a good job and they are cycle-specific, which is nice. Many of the moves are the same as you'd find in other core-specific workouts.

My DH does these DVD's all the time (particularly the stretch one) because he finds them easier to follow than my other workouts. I think it's less intimidating to him to workout with a guy who's got similar flexibility challenges as he does. H does my workouts with me and gets annoyed that he can't really copy the moves because he doesn't have that kind of flexibilty. It's easier for him to follow the Cycle-core workouts and yet they are still plenty challenging.

As far as improvement? Neither of us has been consistent enough to see it...perhaps by next spring we'll be better equipped to answer that question!