3 weeks into the 2015 NFL preseason, there were 25 NFL players that suffered a torn ACL. When these types of injuries occur, the athlete is guaranteed to miss the entire season as it takes 9 months to fully recover. After this many season-ending injuries occurred in the preseason, many questioned the importance of having a preseason, especially for starting athletes that have already built a reputation. One of these athletes was Aaron Rodger's (Green Bay Packers' QB) star wide receivers, Jordy Nelson, who went down with a non-contact ACL injury in a preseason game against the Pittsburgh Steelers. "It's difficult to lose a guy like that – in a meaningless game. It's disappointing that you have injuries like this in preseason." Rodger's said. According to the American Medical Society of Sports Medicine, an estimated 200,000 ACL-related injuries occur annually in the United States, with approximately 95,000 ACL ruptures. Approximately 100,000 ACL reconstructions are performed each year. The incidence of ACL injury is higher in people who participate in high-risk sports such as basketball, football, skiing, and soccer.
How Does an ACL Injury Happen?
Researchers believe there are external and internal factors associated with ACL injury. External factors include any play where the injured athlete’s coordination is disrupted just prior to landing or slowing down (deceleration). Examples of a disruption include being bumped by another player, landing in a pothole, or a ball deflection. Other external factors which have been studied include the effect(s) of wearing a brace, shoe-surface interface (how certain types of athletic footwear perform on different surfaces), and the playing surface itself. Internal factors include, increased hamstring flexibility, increased foot pronation (flat-footed), and variations in the nerves and muscles which control the position of the knee. Nerve/muscle factors pertain to the interaction and control of the knee by the quadriceps and hamstrings muscles in the legs.
Careful study of videos of athletes tearing an ACL show that approximately 70 percent of these injuries are non-contact and 30 percent occur during contact, according to the American Orthopedic Society of Sports Medicine. The non-contact injuries usually occur during landing or sharp deceleration. In these cases, the knee at the time of injury is almost straight and may be associated with valgus (inward) collapse). The athlete often lands with a flat-foot position and the leg is placed in front or to the side of the trunk.
How can an ACL Injury be Prevented?
The focus of current prevention programs is on proper nerve/muscle control of the knee. These programs focus on plyometrics, balance, and strengthening/stability exercises. Plyometrics is a rapid, powerful movement which first lengthens a muscle (eccentric phase) then shortens it (concentric phase). The length-shortening cycle increases muscular power. An example would be an athlete jumping off a small box and immediately jumping back into the air after contact with the floor. Balance training commonly involves use of wobble or balance boards. On-field balance exercises may include throwing a ball with a partner while balancing on one leg. To improve single-leg core strength and stability, athletes perform exercises such as jumping and landing on one leg with the knee flexed and then momentarily holding that position.
High-intensity plyometrics may be key in reducing the number of ACL injuries. To be most successful, plyometric training should be performed more than once per week for a minimum of six weeks. Athletes are taught proper landing techniques which emphasize landing on the balls of the foot with the knees flexed and the chest over the knees. The athlete should receive feedback on proper knee position to prevent inward buckling. Many of the newer programs are being adapted by coaches as an integral part of warm-up during practice, such as jumping over a football and landing in the correct position.
7 Knee Exercises for ACL Injury Prevention
Knee Exercise 1) Basic Squat
- Stand with feet shoulder-width apart.
- Lower your body with your glutes first as if you were to sit back in a chair.Do not let your knees go past your toes.
- Come back up to starting position, driving your weight through your heels and not your toes.
Knee Exercise 2) Jump Squat
- Doing the same thing as your basic squat, but jumping in the air after lowering your glutes
- Make sure that your hip, knees and feet are aligned.
- Land softly on your heels, in a seated position – this will focus on your hip strength.
- Do not let your knee bend inside when jumping and landing- this is known as knee valgus or knee collapse.
Knee Exercise 3) Lateral Bound
- Assume a half squat position facing 90 degrees from your direction of travel. This will be your starting position.
- Allow your lead leg to do a countermovement inward as you shift your weight to the outside leg.
- Immediately push off and extend, attempting to bound to the side as far as possible.
- Upon landing, immediately push off in the opposite direction, returning to your original start position.
- Continue back and forth for several repetitions.
Knee Exercise 4) Step Ups
- Place your right foot on a an elevated platform.
- Use your heel to drive yourself up, lifting your other knee high.
- Flex your hip and knee muscles as you lower yourself in the starting position.
Knee Exercise 5) Ball Hamstring Curl
- Start by laying on your back with your feet on top of the ball.
- Extend your legs out so that your ankles are on top of the ball when fully extended. This is your starting position.
- Raise your hips up with majority of the weight on your shoulders and feet.
- Flex your hamstrings as you pull the ball in towards you, flexing your knees. Hold this flexed position for a moment, then return to your starting position.
- Increased level of difficulty by doing single leg hamstring curls.
Knee Exercise 6) Ball Walk Out with Kick Up
- Lay on top of the physio ball and begin to roll over it until your shins are on top of the ball with your hands on the the ground holding your body parallel to the ground.
- Kick each leg up slowly as you focus on strengthening your core.
- Begin to walk back with your arms as your roll back to the starting position. Do 5 sets of Ball Walk Outs.
Knee Exercise 7) Single-leg Deadlift
- Hold the weight in the opposite hand from the leg that you will have planted.
- Keep your knee slightly bent as you begin to lower your upper body down, bending at your hip with your other leg extending back behind you to balance yourself.
- Lower the weight until you are parallel to the ground, you will feel your hamstring stretch.
- Return to the upright position with thrusting through your hamstrings, hip and lower back.
- An ACL injury occurs 70% of the time from a non-contact move. This non-contact move normal occurs in sudden deceleration and landing positions.
- Knee Valgus(knees bend inward) can associated with a higher risk of an ACL injury.
- Plyometric training and balance exercises are great ways to trigger your nerves/muscles to respond better to your knees' rapid twists and turns.
- Our Enerskin Knee Sleeves have been worn by many athletes recovering from a torn acl and have garnered great responses to speed recovery and help prevent future knee injuries.
Knee Exercises AAOS
Daily Snark - 2015 Torn ACL Team
Suntimes - NFL players ACL Injuries