If you have suffered a serious knee injury in the past have had recent knee surgery, activities that in-volve a lot of running are going to be counterproductive for you. However, if you can find an effective low impact workout that is gentle on your joints, your previous injuries should be of no concern.
If you have bad knees, one of the most important things to keep in mind is that running is your adversary. When you are running, every stride you take puts the equivalent pressure of three times your body weight on each of your knees. If you have bad knees, you should do your best to avoid running, jogging, jumping, lower-body weight training activities (such as squats), and most high impact sports.
An exercise that uses the leg muscles without putting much strain on the joints is bicycling. Whether you ride an actual bike or an exercycle, cycling can be the perfect exercise for someone with bad knees as it is low impact. Often, the exercycle is a favorite tool of trainers and physical therapists for their pa-tients’ rehabilitation.
Elliptical machines (crosstrainers) provide many of the same benefits as running, but like bicycles, they do not exert must strain on the joints. The motions employed by elliptical machines are something of a cross between biking and walking or running, using mainly the legs to propel movement. They also pro-vide a workout for the arms, albeit to a lesser extent, as they are the secondary force in making the ma-chine move.
A favorite exercise for people with bad knees or people rehabbing from injury is swimming. Because of the combination of resistance provided by the water and the simulated weightlessness it projects on the body, swimming can burn a lot of calories without straining the knees or other joints. It is a great cardio-vascular exercise that is a great option for weight loss, rehabilitation, or basic fitness activity.
Any workout that can avoid using the lower body altogether is ideal for people with bad knees. Upper body weight training, including bench presses, curls, chin-ups, and pushups among other activities can be used for general fitness (using less weight for more repetitions) or for muscle growth (using more weight with less repetitions). Similarly, workouts that focus on the midsection such as crunches can be added to a fitness routine without any effect on the knees.