Many doctors encourage their patients to workout regularly but will also tell them to stay away from the treadmill. While avid runners aren’t big fans of the treadmill, beginners all seem to flock toward them. Treadmills put far more stress on your knees compared to some other equipment you find in the gym. With every impact of your foot against the treadmill belt, you rely on your knee to cushion the blow; however, if you have had a knee injury or a tendency toward joint problems, your knees will be better off on a stationary bike than on a treadmill. Click the link to see which other workout machines are great for cardio training without the harsh wear and tear on your joints and knees.