Neuromuscular training programs significantly decrease anterior cruciate ligament (ACL) injury in female athletes participating in high risk jumping and cutting sports, like soccer, basketball, volleyball, field hockey and lacrosse. In seven ACL injury prevention-training studies, the decrease of ACL injuries ranges from 24% to 82%. There are over 50,000 debilitating ACL injuries occurring in female athletes each year. At the college level it is 1 in every 20 athletes, while in high school it is 1 in every 50 to 100 athletes per year. The female athlete is on average four to five times more likely to sustain an ACL injury when compared to the male athlete playing the same sport.
For the female athlete, an ACL injury is devastating to their athletic career. ACL injuries result in surgery followed by six months of rehabilitation. Most surgeries are successful and within a year the female athlete returns to the playing field at her previous level of performance. More important, 50% of the athletes will demonstrate some signs of irreversible arthritis within ten years, therefore prevention training is a must.
Most ACL injuries occur through a non-contact mechanism during deceleration while landing or making a lateral pivoting maneuver. Female athletes demonstrate four neuromuscular imbalances that may put them at greater risk. These neuromuscular imbalances include:
- Ligament dominance which increases load on the knee joint.
- Quadriceps dominance that decreases knee flexion recruitment and strength.
- Leg dominance that increases leg-to-leg differences in muscle coordination and strength.
- Trunk dominance, which increases motion of the body over the body's center of mass or pelvis.
Training programs alter and improve active knee joint stabilization. A trained female athlete reduces her increased rate of ACL injuries to equal the untrained male athlete in the same sport.
The untrained female athlete allows increased tension to develop in her ACL to stabilize her knee rather than using the athletes controlling muscles. This occurs during deceleration and pivoting against ground reaction forces. This results in a ligament-dominant rather than muscle control position (increased flexion and knock-kneed), which causes increased ACL tension and injury.
A second problem is imbalance of the quadriceps and hamstring muscles. First the hamstring muscles are relatively weak compared to the quadriceps muscles. Second, female athletes have a tendency to activate the quads over the hamstrings to stabilize the knee joint. This occurs in both timing and full recruitment of muscle contraction. The imbalance stresses the ACL to stabilize the knee joint.
The next imbalance is leg dominance. The female athlete often demonstrates greater strength and coordination in one leg as compared to the other. Limb dominance places both the weaker and less coordinated limb and the stronger limb at increased risk of ACL injury. The weaker limb is compromised because of its inability to dissipate force while the stronger limb is subject to higher forces due to increased dependency in high demand situations.
Finally trunk dominance is characterized by increased motion of the body's center of mass. Motion of the females trunk is often excessive and directed by the body's inertia rather than by the athletes core and lower leg muscle contraction pattern and strength.
Successful neuromuscular training programs incorporate the following:
- A dynamic warm-up followed by plyometric and jump training emphasizing body posture and control, trunk positioning, dynamic core balance and entire body control.
- Also included are strength training for the core and lower extremities and sports specific aerobic and skill components through both pre-season and in-season training programs.
- Neuromuscular training programs are successful and decrease the injury rate by teaching the female athlete to avoid vulnerable positions, improve strength, flexibility and proprioception, which is the awareness of their body position in space.
I highly recommend all female athletes become involved in a neuromuscular training program before participating in a high level recreational, high school or college sport.