My knee cries the same sob story as everyone else's: it hurts going up and down stairs, when I sit on it, cross my legs, and, most aggravating of all, when I try to exercise. If you've gone through an injury that has permanently damaged your knee, or you just a knee that likes to inflame itself when you want to play, there's still ways to exercise and get the most out of the beautiful spring weather outside. Here's some ideas how.
Rollerblade: Rollerblading is a not so jarring to the knees as running or jogging, especially if it is done for a moderate distance and time. You can keep it to flat level sidewalks and trails, or you can push yourself with a hill or two. Either way, you're building up your back end muscles and your quadriceps, which will help take strain off of your knees in other situations.
Biking: Keeping your bike in a lower gear can allow you to ride rather long distances with little pain. On a recent bike ride, I didn't realize that the more difficult the gear I was riding in, the more strain I was putting on my knee each time I pushed the pedal down. I changed the gear to get up a hill, and the twinges of pain I had been feeling eased considerably.
Walking: Walking with weights can increase the difficulty of your walk if you find you are no longer able to stand your usual jog or run. Ankle and hand weights are available from fitness and sports stores, ranging from light to heavy. Walking quickly and moving your arms as you would when you run also will increase your heart beat. Weights and arm movement increase the intensity of your work out, and you will likely feel just as challenged walking in this way as you would on a run.
Pilates: Pilates classes and videos to exercise from at home is another great way to exercise without causing your knees undue aggravation. The stretching and strengthening of other leg muscles will, in the long run, help compensate for your knee not being in the best of shape. Some Pilates work outs are more benign than others, and the more advanced ones will leave you breathing hard and burning calories.