This Exerpuetic 900XL Magnetic Recumbent Bike with Pulse is great for exercise and also great for help in strengthening the knees. I use this bike often as well as my mom who has arthritis in the knees. Her doctor suggested a recumbent bike so this is the one we bought. It's a great bike for the price we paid. I use it a few times a week and love the workout I get from it. There are tons of different resistance levels to make for a lighter or more intense workout. I love the ease of use and how awesome my legs feel after a hard workout on this bike. The only thing I don't like is if I ride it for too long my feet and bottom start to fell numb or tingle. There are handles by the seat or in front of you by the screen which makes it nice to be able to change it up from time to time. If you are looking for something to use to get a great low impact workout I would highly recommend this bike.