MEDICAL CORNER: Preventing ACL Tears


By JOHN SMITH, MS, PT, Cert. MDT

ACL Tears in Football Players: How can we help prevent them?

It is said that an ACL tear is by the far the worst injury that a football player can suffer. It wasn’t long ago that an ACL tear was thought to be a career ending injury, and even with today’s surgeries and medical advances, it is still not guaranteed that an athlete incurring this injury will be able to return to the same performance level. 


As you may know, a hot topic in the NFL this year has been the return of Adrian Peterson to football just eight months after suffering an ACL injury. This is a feat that most athletes with this injury do not achieve for many reasons including, but not limited to, healing time, rehabilitation progress, and surgery procedures.  


You may also remember when Jerry Rice, the NFL hall of fame wide receiver who suffered an ACL tear, returned to play 16 weeks after the injury, but then suffered another knee injury that ended his season during that game.  Jerry Rice himself even said that he probably returned too quickly to the game consequently re-injuring his knee.  

Average high school and younger athletes can typically return to the sport between 8-11 months after the injury. There are many criteria that decide whether an athlete is able to return to sport, including confidence in the knee, muscle strength, the ability to perform a single leg test (on the side that has undergone surgery) above 85-90 percent of what the opposite leg can do, and many others that need to be considered as well.


Research shows that there any many factors that lead to ACL injuries.  I have noticed an increasing trend of healthcare and sport performance professionals who offer programs that provide education and injury prevention for ACL.  It is important to remember that athletes will always suffer injuries on the football field because it is a contact sport. 


However, it is my professional opinion that performing certain exercises and educating ourselves on proper mechanics, we can certainly decrease our chances of having an ACL injury.

What can we do to prevent ACL injuries? ACL prevention should include flexibility, strengthening and plyometric exercises. It should also include education on the proper mechanics for jumping and the avoidance of vulnerable positions for the knee. 


When an athlete has poor flexibility and weakness in the lower extremity, plus poor postural alignment and technique with sport activity, there is an increase in stress on the ligaments in the knee, therefore making the knee more vulnerable for injury.  Below are some tips on how to prevent ACL injuries.

First, it is important to increase flexibility in the lower extremities. Increasing flexibility will normalize the range of motion in the knees and the hips, decrease joint stiffness and reduce soreness after play. This includes both static and dynamic stretching for the hamstrings, calves, hip flexors and quadricep muscles.  I prefer dynamic stretches for athletes over static stretches because they are functional and they stress the eccentric phase of the muscle contraction. One example of a dynamic stretch is performing walking lunges in multiple planes, such as to the side, front and back (moving forward or backward).  One example of a static stretch, on the other hand, is when we hold a hamstring stretch for at least 30 seconds without bouncing. Though my preference is concurrent with the recent trends in leaning toward a majority of dynamic stretches, the combination of both dynamic and static is still important in keeping the muscles and joints flexible and ready for movement.


Secondly, strengthening the muscles in the lower extremity is equally important in the prevention of ACL tears. When the muscles in the leg are stronger, particularly those in the back such as the hamstrings and gluteal muscles, the stress we put on the ligaments in knee is lessened. Balanced strength that includes the joints below and above the knee is critical in decreasing the stress on the knee as well. I also emphasize single leg strengthening exercises and encourage training of the non-dominant side. Strong gluteal muscles help control and prevent against inward stress on the knee during activities such as cutting, pivoting and jumping. I am a strong believer in eccentric exercise, and research has shown that more injuries occur in this phase of movement, so I strongly encourage the inclusion of these kinds of exercise in your strength training.  Athletes should also incorporate the whole chain of muscles which includes the upper body, core and legs when performing sport specific strengthening exercise. So revisiting your off season strength training program may be beneficial.


Third, is avoiding vulnerable positions that create stress on the knee. When you squat or perform a lunge, the knee should stay in line with the foot and stay behind the toes.  Any movement of the knee moving inward when doing these activities creates more stress on the knee.  Athletes should practice jumping and squatting in front of a mirror, while paying close attention to the knees to ensure they don’t move inward when initiating the jump and with landing. Another good exercise is a single leg lateral step up. This exercise can be performed on the bottom step facing sideways with one leg on the step and the other off the side. When performing the exercise, you lower the leg that’s off the step toward the ground while bending the knee on the step. It is important to the keep the hips level while bending the knee on the step. While doing the exercise you should concentrate on keeping the knee over the foot, behind the toes and don’t let the knee move inward when it is bending.


Fourth, you should improve your proprioception, which is a fancy word for balance.  In physical therapy we use proprioceptive exercise for injuries because injured soft tissue loses its proprioceptive feedback. It is also important to do this type of exercise for preventive measures. This kind of exercise will challenge the muscles and joint receptors, so they learn to respond more quickly to different types of surface or positions during sport activity. There are many exercises that can be used to challenge your balance; one of my favorites is the one-legged squat and reach. This exercise can be easy or advanced by simply changing the surface you stand on (ex: flat surface or foam) and by changing the directions or height at which you reach (ex: reach for a cone on the floor across the body or just reach forward for the back of a chair). It is also important to point out that when you perform this exercise you should avoid an inward movement of the knee.


Lastly, you should include plyometric exercises.  Plyometrics are exercises designed to produce powerful, fast movements. Most plyometric exercise includes jumping, so it is important that you avoid the stressful movements like hyperextension and inward movements of the knees. I also like to emphasize a soft landing when performing plyometric exercises to encourage control and prevent excessive jarring and stress on the joints. Great plyometric exercises for the ACL include lateral/forward/backward hops over cones, squat jumps/vertical jumps, box jumps and two legged stadium stairs jumps.


So, whether you play football or a different sport, these are great preventive measures for both male and female athletes.  It is important to remember that these are suggestions for athletes without injury. If you suspect an injury in your knee I would advise that you seek assistance from your athletic trainer, orthopedic physician or physical therapist.


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John Smith MS, PT Cert. MDT is a Physical Therapist and the clinic director at Preferred Physical Therapy (www.kcppt.com) located at 8437 State Ave KCK. He specializes in orthopedic injures and his professional interest include spine rehab, injuries of the shoulder and knee, sports injuries, running injuries and post operative rehab.