The anterior cruciate ligament (ACL) provides stability and support to the knee joint. It connects bone to bone and prevents the lower leg from sliding too far forward as well as preventing excessive motion in the knee.

Unfortunately, ACL sprains or tears are one of the most common types of knee injuries and they are especially common among athletes. Sports that require frequent direction change, starting/stopping, and jumping see an especially high rate of ACL injury.

Luckily, there are some steps that athletes can take to try to prevent these injuries. By focusing on flexibility, strength, and plyometric exercises, athletes can reinforce the muscles surrounding the knee, making an injury to the ACL less likely. Here are a few suggestions for exercises that do just that:

Flexibility—it’s always a good idea to stretch before exercising to warm up the muscles, reduce stiffness, and prevent injury.

1. Calf stretch
Stand with your right leg slightly forward and bend at the waist until your hands are touching the ground. Make sure to keep your right leg slightly bent and your left leg straight with your left foot flat on the ground. Hold for 30 seconds and repeat with the other leg.

2. Inner thigh stretch
Sit on the ground with your legs evenly spread and bend forward at the waist, keeping your back straight. Reach to the left with your left arm and bring your right arm over your head. Hold for 30 seconds and repeat with the other side.

3. Hip flexor stretch
Lunge forward with your right leg and drop your left knee to the ground. Place your hands on top of your right thigh and push your hips forward, making sure they stay square with your shoulders. Hold for 30 seconds and repeat with other side.

Strength—these exercises will strengthen the supporting muscles in the knee as well as increase agility and coordination.

1. Wall squats
Lean your back against a wall with your feet 15-20 inches away from the wall. Slowly bend your knees and slide down the wall until your knees are directly over your ankles. Hold the position for 20-30 seconds and repeat 5-10 times.

2. Walking lunges
Lunge forward with your right leg, making sure that your right knee is above your right ankle and that your left (back) knee drops straight down. Next, lunge forward with your left leg. It’s important that the motion is controlled and that your knee does not cave inward when lunging. Do this 10 times on with each leg and then repeat the exercise.

3. Single Leg Balance
Stand on one leg with your knee slightly bent and your hip, knee, and foot aligned. Keep your balance for 20-30 seconds and repeat 10 times on each foot.

Plyometrics—these exercises increase strength and agility in the knees as well as build power.

1. Lateral hops and front/back hops
The most important part of this exercise is the landing. Weight should land softly on the balls of the feet and roll back gently onto the heels. It’s also important for the knees to be slightly bent and the hips to be straight when landing.

For lateral hops, place a cone (or other 6” object) to your left and hop over it, landing softly as detailed above. Repeat this exercise to the right, and do about 20 reps total. Then, do front to back hops.

If you participate in sports that require frequent direction changes or starting and stopping, it’s a good idea to consult a physician about which ACL prevention steps are the right ones for you to take. Taking preventative measures may save you from a painful ACL injury and a long road to recovery.