Natalie Voskanian says that any athlete can easily check his or her risk for knee injury with some simple tests developed by Sportmetrics, a nationwide anterior cruciate ligament (ACL) injury prevention program. Professional trainers often administer such tests in a gym, but, Voskanian says, "You can also do them by yourself with a mirror."
You can see a demonstration of these tests on YouTube or at the Sportsmetrics website, sportsmetrics.org/knee-injury-test.
Drop-jump test: Jump from a stable surface about 24 inches off the ground, land with both feet and immediately jump straight up again. If your knees cave in during either landing, you may be at extra risk for a knee injury.
Triple-hop stability test: Take three hops forward on one leg, and try to hold the final landing for five seconds. If you struggle to stay upright, you may need balance and strength training to protect your knees.
Single-leg squat test: Standing straight on one leg with your hands on your hips, bend your other leg to form a 90-degree angle at the knee. Squat down as low as possible five times, and then switch legs. If you have trouble keeping your balance, your knees could be in danger.