If your cat eats dry food, he's more prone to constipation than a cat who eats wet food due to the decreased moisture content. Your vet will do a simple test to determine your cat's hydration level by pinching a fold of skin on his shoulders and pulling up. If it snaps back into place when released, he's well hydrated.
Comparing the Calorie Burn. In terms of calories, a 30 minute treadmill running session at 6mph for an 155lb adult will burn around 350 calories. The same size adult will burn around 260 calories in 30 minutes on a Spin bike at a steady pace. However, a Spinning class is much more intense so you can expect to burn anywhere from 400-600 calories if you push yourself.
I ride a bike 3 times a week for about 1.5-2 hours and do approx 25 miles on the road (avg 15 miles/hr). We wondered in spin class the other day how many miles we go (we do warm-ups, jumps, sprints, intervals, climbs (1st, 2nd, 3rd positions) for a 60 min class taught by a 25 year old playing pop/hip hop. Update: So I guessed 15 miles and got laughed at!