During the active summer and fall months, few things get more wear than the knees, but you can help protect your knees from injury by stretching, the Reebok Aerobic Information Bureau advises.

Start by warming up your body for two to five minutes. Be careful to feel the stretch in your hips rather than ankles, and don't strain so much that you feel stress in your lower back. The best injury prevention, according to The Physician and Sportsmedicine magazine, is to keep the knee joint flexible by stretching. This helps keep the knee aligned during movement.