Terminal Knee Extension Exercises

Terminal knee extension is the end of the range of motion for your knee. An injury or surgery can cause you to lose the ability to "lock out" your knee. Exercises to get terminal knee extension back are often an integral part of rehab programs.

Surgery to repair your anterior cruciate ligament (ACL) may lead to a difficult recovery. This ligament helps keep your knee intact, and injuring it may lead to instability and a limited range of motion. Injuries can occur during athletic competitions or at the gym while you're working out.

There are both partial and full tears of the ACL, according to the U.S. National Library of Medicine. A doctor can determine if you had a full tear and recommend surgery. If you have surgery to repair a torn ACL, going through the rehab process properly is essential for regaining healthy knee function.

One of the most important steps toward full recovery is regaining the ability to reach terminal knee extension. According to the University of Wisconsin, the goal in rehab is to get the injured knee back to the same range of motion as your healthy knee. That can mean a full lockout, plus up to 5 degrees of hyperextension.

Read more: What Muscle Groups Are Used to Flex the Knee?

As discussed above, your goal within the first four weeks of surgery is to restore your range of motion. A September 2017 study published in Current Reviews in Musculoskeletal Medicine states that achieving full knee extension lays the foundation for a safe rehab process and should be achieved as soon as possible. If you don't get full knee extension back quickly, it might never come back, as the researchers point out.

Exercises to achieve terminal knee extension, or TKE, are relatively simple but require a little bit of setting up. These are not the kind of exercises you'd use to get big, strong quads, but they're important in a rehabilitation setting.

A small study published in Biomedical Research in May 2017 discusses the steps you need to take after you regain terminal knee extension. Instead of patients going through ACL rehabilitation, they used people who had knee replacement surgery. Researchers concluded that functional exercises like squats, lunges and balancing drills may help reduce pain and strengthen the quadriceps.

Read more: Can I Do More Damage Walking on a Torn ACL?

Not sure where to start? Try the following knee extension exercises. Consider working with a physical therapist to help you learn proper form.

Move #1: Forced Leg Extensions

This incredibly simple exercise can help you regain terminal knee extension and focus on what you're doing. Emory Healthcare suggests performing this movement for five to 20 minutes, once or twice a day.

1. Sit on the floor with your legs straight.
2. Try to let the backs of both knees rest on the floor.
3. If one knee can't touch the table, take one hand and press it down until it can do so.
4. Hold this position for 30 seconds, then switch to the other knee.

Move #2: Prone Knee Extensions

This is another simple TKE exercise that only requires a table and a surface to lie on. The Dartmouth-Hitchcock Medical Center uses it as part of their ACL surgery rehab program.

1. Lie on a table or the ground on your stomach, with your legs straight.
2. Roll up a towel and place it under your shin bones near your feet.
3. Straighten your knees and hold for five seconds.
4. Slowly return to the starting position. Repeat 10 times.

Move #3: Quad Sets

The quadriceps muscle is in the front of the thigh. It's responsible for extending your knee, making it the most important muscle for knee extension. The following movement can help you isolate this muscle and use it to achieve terminal knee extension.

1. Sit on the ground with your tighter leg straight out.
2. The healthy leg can stay bent with your foot planted on the ground.
3. Prop yourself up with your hands or lean against a wall.
4. Press the back of the knee of the straight leg against the ground and squeeze your quad muscle.
5. If you can't touch the ground, place a towel underneath the knee.
6. Hold the contraction for six seconds then rest for 10. Perform eight to 12 repetitions several times a day, says Kaiser Permanente.