What could you do for cardio exercise if you have achilles tendinitis?

Swim: Or lay off lower body and perform upper body excercises.

NWB: Limit weight bearing exercise, a recumbant bicycle is good as well as swimming.

Exercise : Swimming is great without using your feet too much also circuit weight lifting with sitting. Sit ups can increase heart rate as well when done quickly.

Have a pool?: Swimming is a great exercise for patients with achilles pain, just watch the kicking. Also elliptical trainers are easy on the achilles if you keep your foot flat and do not raise up on the toes or forefoot. Biking can be ok depending if you have mid tendon tendinitis or insertional tendinitis. Try adjusting the seat height and place the pedal back farther than normal.