An injury to the anterior cruciate ligament (ACL) of the knee, particularly one that requires surgery, can sideline even the most dedicated athlete for months, if not longer.

Straighten Up: While lying on your back, straighten your leg, then slowly raise it as high as possible and hold for a few seconds. You may not be able to elevate the straight leg very high in the beginning, but stick with it. In fact, you can simply place the foot / ankle on a support and straighten it without lifting if necessary.

Contract the Quad: Again lying on your back, straighten the knee and tighten the quadriceps (the large muscle group located in the front of the upper leg) for 10 seconds. Release and repeat 10 times several times a day.

Hang ‘Em Low: Lie on your stomach on an elevated surface such as a bed or table, with the edge of the surface just above your knee. Let your legs hang off the edge for 1 minute or as long as you can, whichever comes first.

Take a Slide: Lying on your back on the bed or a comfortable surface, slide the heel of the foot toward your butt, attempting to bend the knee while keeping the heel flat. Hold whatever position you can achieve for 10 seconds; then slowly slide the foot back to the starting position. Repeat 15-20 times, several times a day.

If you’ve recently suffered an ACL injury and/or undergone surgery for an ACL injury, your doctor should be providing you with these and similar exercises to start you on your road to recovery. And if you’ve never suffered a knee injury, but want to make sure things stay that way, your doctor can teach you simple stretches and strengthening exercises to keep your knee out of trouble.