Preventing ACL Tears

There are modifiable and unmodifiable factors that predispose to knee injury. Some factors are out of your control such as your age (young patients and teens are at highest risk), sex (females may have a 2-6x greater risk than males during the same activity), soft tissue composition (lax joints), bony geometry (high tibial slope, discussed elsewhere), and history of ACL tear (if you have torn your ACL you are at a higher risk of retearing the same knee or your other knee). By strengthening the muscles around the knee and improving the way they activate, you can optimize the way the bones of your knee move, shifting high loads during landing and contact to the surrounding muscles and tendons instead of to the deeper ACL. Research confirms this, as a training program can prevent tearing(1) or re-tearing your ACL, with the risk of injury decreased by as much as 73%.

Even our cherished sports heroes such as Tom Brady, Derrick Rose, Rob Gronkowski, among many others, have torn their ACL even when in top shape and at the top of their game. Anyone is susceptible to injury, and we are not always thinking about protecting ourselves when in the heat of competition. One interesting finding is that prevention programs not only lower injury rates but also boost athletic performance, like improving sprint speed and vertical jump, which might motivate athletes to stick with them(2).

While you can do a training program on your own individually, best results are with an involved parent or coach who can watch your form and ensure you are properly warmed up prior to competition. Whether you are in season or off, carving out 15-20 minutes 2-3 times a week ensures optimal results. Consistency is best, and it helps to tie in training with scheduled sport participation, ideally prior to practices or games, or on off days or days you are in the gym.

There are a few strategies of ACL tear prevention training, each with unique exercises supported by high-quality evidence. These strategies include I. neuromuscular training, II. plyometric training, III. strength training, IV. agility and cutting technique training, V. core stability training, and VI. flexibility and dynamic stretching training.

Neuromuscular Training

• How It Works(3): Top athletes have great control of their nervous systems. The nerves need to properly communicate with muscles for coordination, muscle activation, and joint stability. This reduces abnormal knee movements (e.g., valgus/inward collapse) during sports, lowering ACL stress.
• Specific Exercises:
  • Single-Leg Balance: Stand on one leg for 30 seconds, progressing to eyes closed or on an unstable surface (e.g., foam pad). Enhances proprioception (joint position) and knee stability.
  • Lateral Hops: Hop side-to-side over a line for 10-15 reps, focusing on soft landings with knees slightly bent. Trains lateral stability and control.

Plyometric Training

• How It Works(4): Enhances explosive power of the muscles, teaching athletes to absorb force correctly. This relies heavily on landing mechanics, reducing knee load during jumps. This strengthens muscles like the quadriceps and hamstrings, which protect the ACL.
• Specific Exercises:
  • Tuck Jumps: Perform 10 jumps, bringing knees to chest mid-air, landing softly with knees bent. Improves power and landing control.
  • Box Jumps: Jump onto a 12-18 inch box, stepping down carefully, for 10-15 reps. Trains proper knee alignment during takeoff and landing.

Strength Training (Focus on Hamstrings and Quadriceps)

• How It Works(5): Strong muscles surrounding the knee, particularly the hamstrings, can counteract anterior(forward) shifting of the tibia(shin bone) that strains the ACL. Balanced quad-hamstring strength stabilizes the joint.
• Specific Exercises:
  • Nordic Hamstring Curls: Kneel with a partner holding your ankles, slowly lower your body forward, resisting with hamstrings, for 6-8 reps. Builds eccentric hamstring strength.
  • Squats: Perform 3 sets of 10-12 reps with body weight or light resistance, keeping knees over toes. Strengthens quads and glutes for knee support.

Agility and Cutting Technique Training

• How It Works(6): Changes in direction can generate rotational torques on the knee that can give way by falling into valgus (inward collapse). Teaching the knee to stay in a balanced position during changes in direction and reduce injury by preventing the knee from going into a risky position. These exercises are particularly helpful for a coach or parent to supervise.
• Specific Exercises:
  • Shuttle Runs: Run 10 yards, pivot, and return, focusing on keeping knees aligned with feet, for 5-10 reps. Enhances cutting control.
  • Figure-8 Drills: Run in a figure-8 pattern around cones 5-10 feet apart, maintaining low center of gravity, for 3-5 circuits. Improves agility and knee positioning.

Core Stability Training

• How It Works(7): Strengthens the core (abdominal and lower back muscles) to improve overall body control, reducing compensatory knee movements that stress the ACL during sports.
• Specific Exercises:
  • Planks: Hold a plank position for 30-60 seconds, keeping spine neutral, for 3 sets. Stabilizes the trunk for better leg alignment.
  • Side Planks with Leg Lift: Hold a side plank and lift the top leg 10 times per side, for 3 sets. Enhances lateral core strength and hip stability.

Flexibility and Dynamic Stretching

• How It Works(8): Increases range of motion and reduces muscle stiffness, allowing the muscles to counteract strain on the ACL during rapid movements.
• Specific Exercises:
  • Dynamic Lunges: Step forward into a lunge, keeping the front knee over the ankle, for 10 reps per leg. Great exercise when warming up.
  • Leg Swings: Swing one leg forward and back 10-15 times per side, holding a wall for balance. Improves hip and hamstring flexibility during warm ups.