How Stretching Can Help With Recovery From ACL Injuries

woman doing kneeling hip flexor stretch

Verywell / Ben Goldstein

The knee is the body's largest and most complex joint, with lots of moving parts held together by four main ligaments. These ligaments, which include the anterior cruciate ligament (ACL), are non-stretchable connective tissues that attach muscles to bones. Unfortunately, these ligaments can be injured, and injury can even be severe enough to require surgery.

Causes of ACL Injury

There are many ways to injure an ACL but most often these accidents happen while playing sports. Basketball players, football players, and soccer players are particularly vulnerable to ACL injuries. Young, female athletes are of greatest risk for ACL sprains and tears, with teenage soccer players at the highest risk, followed by male athletes playing football.

Even if you aren't a high-level athlete, you can still injure your ACL. Tears can happen in contact injuries, in which a direct blow to the knee pushes it into an abnormal position. In non-contact injuries, which are more common, the person swiftly changes direction, pivots, or hyperextends the knee while in motion, resulting in a tear.

Symptoms of ACL Injury

Common symptoms of an ACL tear or sprain include:

  • Sudden knee pain, sometimes accompanied by a popping sound
  • Reduced knee mobility
  • Knee swelling that lasts more than 48 hours
  • Difficulty bearing weight on the knee

Sometimes an ACL injury is evident at the time of the injury, but not always. It's vital to get checked by a doctor if you suspect an ACL injury to prevent further damage.

What's in a Knee?

Three bones come together to form the knee joint: the thigh bone (femur), the shin bone (tibia), and the kneecap (patella). The muscles that connect them are the quadriceps (the large muscles that make up the front of the thigh); the hamstrings (the complementary large muscles in the back of the upper leg); the adductors (the muscles of the inner thigh, which help stabilize the knee joint) and the calf muscles of the lower leg.

Additionally, there is the length of connective tissue called the iliotibial (IT) band that connects the hip bone to the knee. The ACL and other ligaments hold everything together.

Easy Stretches for ACL Injury Recovery

While you can't change the structure of the ligaments or bones that make up the joint, there's a lot you can do to help rehabilitate, stabilize, and protect the knee. One important way to aid recovery from an ACL injury is to keep the muscles that support the knee flexible with stretches. These muscles need to be pliable enough to allow the joint to move through a full range of motion and strong enough to support them.

Studies show that progressive exercise programs, including some of the ACL stretches below, are a key component to ACL injury recovery. Additionally, people who use ACL stretching regimes in recovery see a significant improvement compared with those who do not.

These stretches can help support ACL injury treatment. They can be a great place to start under the care of your doctor and physical therapist. Always consult your doctor or physical therapist before beginning a new exercise regime, particularly post-injury. Doing these exercises should not cause pain. If something hurts, stop and consult your provider.

Calf Stretch

Towel Calf Stretch
Verywell / Ben Goldstein
  1. Sit on the floor with your legs out in front of you.
  2. Flex your right foot and wrap a towel around the ball of the foot (just below your toes).
  3. Gently pull the ends of the towel, keeping your right knee straight. You may feel the stretch behind your heel or your knee, depending on where the muscle or tendon is particularly tight.
  4. Hold for 15 to 30 seconds, and then slowly release.
  5. Rest for a few seconds, and then repeat the stretch 3 to 5 times on each leg.

Quadriceps Stretch

Standing quadriceps stretch
 Verywell / Ben Goldstein
  1. Stand next to a sturdy chair or recruit a friend to help you. Place your left hand on the chair or your partner's shoulder. 
  2. Bend your right knee behind you to bring your heel toward your right buttock. Reach back with your right hand and grab the front of your right ankle.
  3. Keeping your right knee pointed downward and next to your left knee, gently pull your heel closer to your butt until you feel gentle tension along the front of your thigh from knee to pelvis.
  4. Hold for 30 seconds, breathing normally, then lower your foot to the ground and switch sides. Do both sides two times. 

Hamstring Stretch 

Hamstring Stretch
Verywell / Ben Goldstein
  1. Sit on the ground with your right leg extended in front of you.
  2. Bend your left knee and rest the bottom of your foot against the inside of your right thigh.
  3. Keeping a slight curve in your lower back, reach your chest toward your knee. Go only as far as you can without hunching over.
  4. If this is far enough to feel a stretch along the back of your leg, stop here. If you have the flexibility to reach forward and grab the toes of your right foot with both hands without losing the curve in your back, that will give your hamstring a little extra stretch.
  5. Breathing normally, hold the stretch for 30 seconds, then repeat with the other leg.

Inner Thigh Stretch

Inner Thigh Stretch
Verywell / Ben Goldstein
  1. While still seated on the ground, extend both legs in front of you, then widen then as far apart as comfortable. 
  2. Keeping the slight curve in your low back, reach both hands in front of you toward the ground between your legs. 
  3. Go just far enough to feel a stretch in your inner thigh.
  4. Hold the stretch for 20 seconds and repeat three times.

Hip Flexor Stretch

Hip Flexor Stretch
Verywell / Ben Goldstein
  1. From standing, step far forward with your right leg.
  2. Drop your left knee down to the ground.
  3. Place both hands on top of your right thigh and lean forward, keeping your hips square with your shoulders.
  4. If you can do this while staying balanced, reach behind you with your left hand and grab your left ankle to pull your foot closer to your buttocks.
  5. Hold for 20 seconds and repeat on the other side.

The Importance of Exercise

In addition to stretching, ACL health and recovery require complementary strengthening exercises. Building up the muscles surrounding the knee help keep it strong enough to safely take on a person's body weight as well as the stopping and starting motions that happen in sports.Greater strength and motor control make for a more stable knee, will enhance rehabilitation, and may prevent future injury.

Research is mixed on how big an impact ACL exercises and stretches have on preventing ACL injury. However, there is evidence, particularly for teen girls, that physical training can reduce the incidence of ACL injury by as much as 72%. The American Academy of Pediatrics recommends that young athletes incorporate knee-supporting strengthening and stretching exercises into their training.

Athletes of all ages can follow this recommendation to help protect their ACLs. Research is clear that keeping the muscles surrounding your ACL both strong and flexible will result in a stronger knee.

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Article Sources
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  1. Wolf SF. ACL injuries in young athletes. American Academy of Pediatrics. Updated March 29, 2019.

  2. American Orthopaedic Society for Sports Medicine. Sports tips: The injured ACL. Updated 2016.

  3. Bordes A. What exercises are best to strengthen my knees?. American Council on Exercise. Updated November 16, 2011.

  4. Eitzen I, Moksnes H, Snyder-Mackler L, Risberg MA. A progressive 5-week exercise therapy program leads to significant improvement in knee function early after anterior cruciate ligament injury. J Orthop Sports Phys Ther. 2010;40(11):705-21. doi:10.2519/jospt.2010.3345