The Science Behind ACL Tears and How Strength Training Protects Against Them

The ACL is one of the most feared injuries in soccer. It can end a season and set an athlete back a full year. Most ACL tears aren’t bad luck, though. They follow a predictable pattern, and that pattern can be trained against.

What actually happens when an ACL tears

The ACL stops the shinbone from sliding forward and rotating under the thigh bone. About 70% of tears are non-contact and happen during a hard cut, a sudden stop, or a landing. Research shows the ligament usually fails within 50 milliseconds of the foot hitting the ground, which is faster than any conscious reaction. In that moment, the body does whatever it has been trained to do.

The typical injury position is the knee caving inward, the foot planted, and the body landing upright with a nearly straight knee. The quads pull the shinbone forward, the hamstrings can’t resist, and the ligament takes force it was never built to handle alone.

Why some athletes are at higher risk

Female soccer players tear their ACL at two to eight times the rate of male players. Much of that difference comes from factors that can be trained:

• Quad dominance. The athlete relies on the quads to stop, and the hamstrings are too weak to counter them.

• Weak hips. The glutes can’t control the thigh, so the knee collapses inward.

• Poor trunk control. The torso sways and shifts load onto the knee.

• Growth spurts. Bones grow faster than strength and coordination can keep up.

• Fatigue. Mechanics break down late in games and late in the season.

How strength training changes the equation

You can’t strengthen the ligament itself, but you can build the system that protects it. One large meta-analysis found that strength training cut sports injuries to less than a third of their usual rate.

• Hamstring strength (Nordics, RDLs) pulls the shinbone back against the quads.

• Hip and glute strength keeps the knee tracking over the foot.

• Deceleration training teaches athletes to absorb force through bent hips and knees.

• Landing and cutting mechanics get drilled until they’re automatic.

• Trunk strength keeps the body stacked during change of direction.

Why consistency matters

Programs like the FIFA 11+ reduce ACL injuries by about half, but only for teams that do them consistently. Two to three short sessions a week, all year long, is what makes these patterns stick.

At VA Revolution, our Strength & Performance sessions are built around exactly these qualities. Athletes develop the hamstring, hip, and trunk strength that protects the knee, and they practice landing, cutting, and deceleration until good mechanics become second nature. It’s consistent, year-round work designed to keep players healthy and on the field.

Bottom line

ACL tears happen in a split second, but the risk builds over months. Stronger hamstrings, stronger hips, and good landing mechanics give the knee its best chance of holding up when it counts.