By: Dr. Rebecca Van Heuklon, DPT, FAFS, FMR
In the introductory article on ACL tears, the different risk factors for having an anterior cruciate ligament (ACL) tear are discussed. For review, there are a number of modifiable risk factors for ACL tears, including weakness and decreased coordination in the core, hips, and legs, decreased sense of body position and movement in the legs, and over-reliance on the quads with weakness in the hamstrings.¹ Research shows that an imbalance of strength, coordination, and motor control in one leg compared to the other can also increase the risk of experiencing a torn ACL.¹ Addressing these modifiable risk factors proactively are a critical component to reducing the risk of an ACL tear. Based on a thorough review of ACL injury prevention programs in the research, here are the key strengthening exercises that should be incorporated into all athletes’ exercise programs.
An important part of any strengthening program is a thorough dynamic or functional warm-up to increase blood flow to the muscles, wake up the nerves, increase joint mobility, and prep the body for sport-specific activity, all of which reduce the risk of injury. Here’s a great instructional video that contains a variety of tri-planar movements included in a typical functional warm-up.
The most important muscles to strengthen are located in the trunk, hips, and hamstring, since weakness of the core and hips contribute to excess inward motion of the knees. Next, the exercises require a commitment of time and adequate instruction on behalf of the athletes and coaches for optimal effectiveness, as high compliance is associated with lower rates of ACL injuries.² Strength exercises are most effective when performed 2-3 sessions each week during both the preseason and throughout the regular sports season.² When the exercises were performed only during the pre-season, they were not effective at preventing ACL tears during the regular season.²
These strengthening exercises are helpful for athletes at any age, but the target age range is athletes between 10-25 year olds who are involved in sports with a high risk of ACL injury such as soccer, basketball, football, or lacrosse. An ACL prevention program is most beneficial in females at pre-adolescence (ages 10-13), as this is the age when young females begin to show strength and coordination deficits compared to their male counterparts.¹
Finally, excellent exercise technique is necessary to gain any benefit at preventing injury; therefore, they are best instructed by a strength and conditioning coach, athletic trainer, or physical therapist who is trained in giving feedback to ensure correct exercise form. Each exercise should be demonstrated with active cueing to improve each athlete’s technique. Once athletes have mastered the correct technique, they can transition to performing the exercises independently. Athletes can also perform the exercises in front of a mirror at home to see their form in real-time to correct any movement errors.
The table below lists the key strengthening exercises to prevent ACL tears for beginners along with advanced options for each exercise. Below the table are pictures and descriptions of each exercise. Pay close attention to the photos and instructions to learn how to maintain joint alignment and utilize good technique. The optimal program for each exercise consists of 2-3 sets of 8-15 repetitions, and is performed 2-3 sessions per week.
| Strengthening Exercises | Beginner | Advanced |
|---|---|---|
| Squat | Squat with Weighted Ball Overhead | |
| Single Leg Squat | Single Leg Squat with Opposite Foot in Different Positions | |
| Forward Walking Lunges | Forward Walking Lunges with Trunk Rotation | |
| Lateral Lunges | Lateral Lunges with Trunk Rotation | |
| Bridge | Single Leg Bridge | |
| Prone Plank | Prone Plane with Lateral Step | |
| Side Plank from Knees | Side Plank from Feet |
Squat
Beginner:
1. Stand with feet shoulder-width apart with arms straight in front of you for balance.
2. Squat back, folding at the hips, aligning the knees over the second toe. Do not allow the knees to fall inward or go forward past the toes.
Advanced:
1. Stand with feet shoulder-width apart. Hold a weighted ball (heavier = more advanced) centered over the head.
2. Squat back, folding at the hips, aligning the knees over the second toe. Do not allow the knees to fall inward or go forward past the toes.
Single Leg Squat
Beginner:
1. Stand on one foot. Hold arms straight out in front of you for balance.
2. Squat back, folding at the hips, aligning the knee over the second toe. The depth of the squat is determined by how deep full control of the knee is able to be maintained. Do not allow the knee to fall inward or move forward past the toes.
Advanced:
1. Stand on one foot. Hold arms straight out in front of you for balance.
2. Squat back, folding at the hips, aligning the knee over the second toe. This time, hold the opposite leg behind you. The depth of the squat is determined by how deep full control of the knee is able to be maintained.
Do not allow the knee to fall inward or move forward past the toes.
Note: This squat can be performed with the non-stance leg positioned out in front, out to the side, or as pictured with the foot behind you.
Forward Walking Lunges
Beginner:
1. Step forward, taking a bigger step than normal, lunging onto your front foot.
2. Lower your hips and bend both knees to a 90-degree angle. Maintain a tall trunk, and do not allow the knee to fall inward or move forward past the toes.
3. Step forward with the back leg, walking forward into the next lunge.
Advanced:
1. Step forward, taking a bigger step than normal, lunging onto your front foot.
2. Lower your hips and bend both knees to a 90-degree angle. Twist the trunk by rotating both hands towards the front lunging leg. Maintain a tall trunk, and do not allow the knee to fall inward or move forward past the toes.
3. Step forward with the back leg, walking forward into the next lunge.
Lateral Lunges
Beginner:
1. Stand with both feet together and pointing straight ahead.
2. Step one leg laterally to lunge, folding at the hip and maintaining the lunging knee behind the toes.
3. Return back to the start position, or continue on to perform a walking lateral lunge.
Advanced:
1. Stand with both feet together and pointing straight ahead.
2. Step one leg laterally to lunge, folding at the hip and maintaining the lunging knee behind the
toes.
3. Rotate both hands towards the lunging leg, turning chest with hands.
4. Return back to the start position, or continue on to perform a walking lateral lunge.
Bridge
Beginner:
1. Lie on your back with knees bent up and feet flat on the floor.
2. Lift hips up so the knees, hips, and shoulders are in a straight line.
3. Hold for 3-5 seconds and slowly lower back down.
Advanced:
1. Lie on your back with knees bent up and feet flat on the floor.
2. Straighten one leg and then lift the hips up so the knees, hips, and shoulders are in a straight line.
3. Hold for 3-5 seconds and slowly lower back down.
Prone Plank
Beginner:
1. Prop yourself up on your elbows and toes, keeping shoulder blades pulled down and back.
2. Brace the abs to hold the body in a straight line. Avoid letting hips or stomach sag.
3. Hold for 30 seconds ; perform 3 times.
Advanced:
1. Prop yourself up on your elbows and toes, keeping shoulder blades pulled down and back.
2. Brace the abs to hold the body in a straight line. Avoid letting hips or stomach sag.
3. Tap one leg out to the side, and repeat with the opposite leg.
4. Perform 2-3 sets of 15 reps.
Side Plank
Beginner:
1. Lie on your side with knees bent and shoulders, hips and knees in a straight line.
2. Prop yourself up on your elbow and knees with your top hand resting on your hip, keeping your body facing forward.
3. Hold for 30 seconds; perform 3 repetitions on each side.
Advanced:
1. Lie on your side with shoulders, knees, and feet in a straight line.
2. Prop yourself up on your elbow and knees with your top hand resting on your hip, keeping your body facing forward. Do not let the hips sag.
3. Hold for 30 seconds; perform 3 repetitions on each side.
Evidence from research shows that a program that contains both strength and plyometric (jumping) exercises are most effective for preventing ACL tears. Next month, we will introduce excellent jumping and, more importantly landing, technique and identify the key plyometric exercises for preventing ACL tears. If you have questions on whether these exercises are right for you or your athlete, or if you are interested in additional modifications or progressions for these exercises, contact Rebecca@motionworkspt.com. The Doctors of Physical Therapy at MotionWorks are trained in sport specific ACL Prevention program design for teams and individual athletes, as well as rehabilitation for ACL tears both before and after reconstructive surgery. Contact MotionWorks Physical Therapy for more information at info@motionworkspt.com or call 920-215-2050.
1. Hewett TE, Myer GD, Ford KR, et al. 2016. Mechanisms, Prediction, and Prevention of ACL Injuries: Cut Risk with Three Sharpened and Validated Tools. J Orthop Res. 34(11):1843-1855.
2. Arundale AJ, Bizzini M, Giordano A, et al. 2018. Exercise-Based Knee and Anterior Cruciate Ligament Injury Prevention: Clinical Practice Guidelines Linked to the International Classification of Functioning, Disability and Health from the Academy of Orthopaedic Physical Therapy and the American Academy of Sports Physical Therapy. J Orthop Sports Phys Ther. 48(9): A1-A42.