Your anterior cruciate ligament, or ACL, is a type of connective tissue inside your knee joint that helps provide knee stability. Injuries to the ACL are fairly common in people who participate in sports and activities that generate significant knee stress. If you damage your ACL, you will likely need to perform certain types of cardiovascular or aerobic exercises as part of your rehabilitation program.
Basics
Your ACL runs diagonally across your knee joint from the back of your femur to the front of your tibia. It gets the "cruciate" portion of its name because it crosses the posterior cruciate ligament, or PCL, which runs through your knee in the opposite direction. Tears in your ACL usually occur when you experience a twisting force on your knee while your foot is planted on the ground. You can also tear your ACL if you receive a blow to the outside of your knee. Women damage their ACLs anywhere from two to eight times more frequently than men.
Initial Rehab Exercises
Non-athletes and older people who lead inactive lifestyles may not need to get their ACLs repaired, according to Massachusetts General Hospital Orthopaedics. However, active young people and athletes typically need to get their ACLs repaired in order to avoid further injuries. In either case, you typically need some form of rehabilitation to recover function in your knee. For the first week or so of rehab, you will usually perform non-aerobic exercises designed to strengthen your knee joint.
Initial Cardiovascular Exercises
In the second week of rehabilitation, your doctor may ask you to start riding a stationary bike once or twice daily on most days of the week. While stationary biking is usually a cardiovascular activity, your purpose at this stage is simply moving your knee joint and increasing your joint flexibility. In the third week of rehab, your doctor may also recommend that you get cardiovascular exercise by going swimming. If this is the case, you will typically only perform less demanding swimming strokes like a freestyle flutter kick.
Later-Stage Cardio Exercises
Between your sixth and 12th weeks of rehab, you can usually start to regain your cardiovascular conditioning with exercises such as walking, rowing, elliptical training, stationary biking and swimming or other water workouts. You will typically only perform these exercises once or twice a week in 20- or 30-minute intervals. After 12 weeks of rehab, you can start getting cardio exercise three to five days a week. If you're healing well, your doctor may also let you run on soft ground while wearing a flexible knee brace.
If you're an athlete, the next step in your rehabilitation will be exercises and activities related to your specific sport. Complete recovery from an ACL injury can take as long as six months. In addition to cardiovascular and strengthening exercises, ACL rehabilitation programs commonly include range-of-motion exercises.
References
- Sports Injury Clinic: Torn Anterior Cruciate Ligament/ACL Knee Injury
- Massachusetts General Hospital Orthopaedics: Anterior Cruciate Ligament Injury (Pages 1-17)
- University of Connecticut Health Center - New England Musculoskeletal Institute: Frequently Asked Questions; Anterior Cruciate Ligament (ACL) Injuries
