Originally Posted by wphamilton

Swimming is a more full-body exercise than either running or cycling and has those concurrent benefits. If all you care about is health of your heart, even just walking briskly gets you 90% or better of the benefits.

For strictly workouts I'll admit that I personally prefer running to cycling, increasingly so as I get older. I know, that's backwards from most people, and I don't actually *enjoy* running like I do cycling, but it's just more beneficial in less time. Purely for cardio, a nice long ride with an elevated heart rate is, like walking, all that's really needed.