Besides seeing a doctor- that hand crank machine can really work up a sweat.

Have you tried boxing? I've often worked up a sweat punching on speed bags and heavy bags. Knees and legs are not required for this activity. If you can pay some fool to stand in front of you with some focus mitts for an hour, you can do some punching on the focus mitts too.

Also, you'll want to try and work with weight training. Muscle burns fat, so with the increase in muscle, you'll at least be working on keeping yourself from getting over fat.

Koffee