specific cardio/aerobic routines that don't use your feet?

hausisse

Swimming, biking and rowing machines aren't options. I think I may have hurt my achilles tendon. I tried chair aerobics but didn't sweat at all... help?

neandermagnon

can you get info about how wheelchair athletes work out? e.g. from blogs. I'd expect a fair amount of it would require a wheelchair, which isn't an option but I'm sure they'd have variety in their workouts and other ways to do cardio.

some exercises like dumbbell crawling you do on all fours, well you use your toes for that one but maybe you could modify it to use your knees, or find others like it that you're on your hands and knees for?

RobinV_Seattle

Shadowboxing? My dad has issues with his feet - he props himself on a stool and starts throwing jabs and crosses for a few minutes at a time. It definitely gets his heart rate up!