One of the many troubling aspects of having Arthrofibrosis in my knee is the lost of the ability to get a good cardio workout. I used to do serious cardio exercises 3-4 times per week on elliptical trainers, rowing machines, stationary bikes and treadmills and I can't use any of these machines anymore. I recently purchased at Amazon a hand ergometer, better known as a hand bike, with the accessory hand pedals, and am very pleased with it. It is called the Magne-Trainer ER Mini Exercise Bike Arm and Leg Exerciser. It seems well made and I think is a good deal for the price - under $250 here in the US. It will take me some time to build up enough upper body strength to be able to push into the cardio zone but with time, I'm confident I will get there. Here's to exercise!