We were in Sears today and for fun we tried out some of the cycling machines. I boosted the seat up on one to have proper leg stretch and rode on one for a minute or so. It said I was doing about 18 mph and I had it set with enough resistance that it felt right doing a higher cadence. I'm guessing 90-100rpm. Anyway after I was done, my upper legs and butt muscles felt like I had really worked them out.
I don't get this when I ride my bike for any amount of time. Why would this be?