I skate almost everyday hardcore for 2 hours, sometimes twice a day. I don't just sit and do tricks, I stay mobile 90% of the time. When I'm done, I'm soaked like gatorade commercial kinda of soaked, and quite exhausted. All the Muscles in my legs are sore along with some parts of my hips and abdomen. I sweat 10 times as much as opposed to doing sprints. I feel it could honestly be a viable cardio source. Anyone have any experience?