BLOG: Why do we train deceleration after ACL injuries?

March 2, 2022 Tom Heeley

By Tom Heeley (MD, Optimum)

The first thing to understand is how the Anterior Cruciate Ligament (ACL) is ruptured and when most occurrences of injury occur.

I have worked with a lot of athletes who have suffered ACL injuries and were keen to return to sport post surgery, as well as those who have not had surgery yet and want to make their knees and lower body as strong as possible before they go into hospital.

Biomechanics

Most ACL injuries occur when changing direction and some can seem relatively innocuous to the naked eye at the time.

Changing direction requires slowing down, planting your foot and pushing off again. Some sports like; rugby, football, NFL, NBA, skiing and netball require sharp changes of direction and decelerating rapidly. As a result, these sports see a greater incidence of ACL injuries.

Netball and NBA have the added difficulty of a hard surface with a LOT of grip causing rapid deceleration. That’s perfect for the game and those who play it but players need to be really well conditioned for those conditions.

Skiing also has the added equipment which is long and can cause excessive rotation forces at the knee as well as large braking forces too.

CHANGE OF DIRECTION

The ACL passively prevents excessive anterior translation and external tibial rotation.

A combination of both of these movements in sport puts the knee in a vulnerable position, however it also provides a lot of power to cut and change direction quickly.

Athletes need to train hard to make their bodies robust enough to accept the movements and use them to their advantage.

Deceleration

To change direction and turn, we have to plant load and decelerate. The ground reaction forces of running are calculated around 2.5 times bodyweight, cutting and change of direction is greater and more towards 6 times body weight so it is easy to see the stresses placed on athletes’ bodies in these circumstances.

Individual tolerance needs to be addressed to deal with increased external load with hamstrings, quadriceps and all matter of other lower limb muscles involved in this conditioning.

If you have suffered from, or would like to protect yourself from an ACL injury, please get in touch and we can explain routines and exercises that can help.