Many gyms offer rowing machines, upper body ergometers, swimming pools, and boxing rooms. These can all be used by those with limited leg function. A rowing machine provides aerobic workouts to the biceps, triceps, pectoralis muscles, and the upper back muscles. An upper body ergometer (arm bike) looks like an upside-down bike that is pedaled with your hands. In the pool, shallow water arm movements with leg stabilization can be done to stress the arms, chest and upper back. With assistance, a seated modified boxing workout can be completed with the aid of medical personnel.
Basic cardio. start off by pumping your arms up and down for 10 counts. Push your arms out to your sides for 10 counts. Now alternate pushing your arms up, then down, then out to your side and back. Do that sequence for 25 counts. Now push your arms straight out in front of your chest then bring your arms back as you pull your elbows back behind you. Complete 25 of these moves. If possible, you can use your thighs to alternate lifting your knees high or kick as you do each upper body move.
http://www.bing.com/videos/search?q=how+to+do+cardio+with+only+one+leg+by+livestrong&qpvt=how+to+do+cardio+with+only+one+leg+by+livestrong&FORM=VDRE#view=detail&mid=7A9E43240D7BAF3D34607A9E43240D7BAF3D3460
http://health.howstuffworks.com/wellness/diet-fitness/exercise/leg-injury-upper-body-cardio-workout-in-bed.htm
Hi there. Well, have you ever tried water aerobics? I'm a big fan. You can do shallow water work outs in which you stand and do the work out with the part of your body that isn't injured. Great resistance and you can get a non impact cardio work out in. It's great!