There are a couple of things we can do to help our knees and protect them from injury. Obviously, most of us know at least one or more people that have suffered from a knee injury. We know that they exist, certainly. And even if you're not having any problems, but you're very active you might want to consider a couple of things.
Number one, when you're weight-bearing or when you're playing sports especially, you might want to wear what's called a neoprene sleeve. This is basically a flexible, pliable, basically brace that you can put over your leg and this can give it a little bit more support for the sport or recreation. They typically have a little cutout in the middle where the kneecap can fit and in general, for all of your weight-bearing activities and certainly your sports, you might want to consider using it.
Number two is proper stretching techniques both before and after sports. Stretching out your quads, your hamstrings, your calf muscles, even your hips. Before and after, if you really want to be serious about prevention and protection. Some strengthening exercises are also probably important. If you're involved in certain sports or certain repetitive sports, like running or cycling, just getting on the floor once or twice a week and doing some isolated exercises for the knee, some leg exercises, some leg curls, in addition to your typical run or your typical sport, might be suggested.
Lastly again, even if there's no pain, you might want to consider icing your knee after sports and after recreation. Typically, there's a buildup of activity that can lead to the swelling and the pain. To be ultra-preventative, you might want to use ice after all sports. It can really be a fool-proof plan. It's stretching, and exercise, some icing, and certainly wearing some sort of protective sleeve or brace can be the four ways to prevent injury.