These 4 structures surrounding the ACL are there to protect and serve.
When someone suffers an anterior cruciate ligament (ACL) injury, most physicians and physical therapists will have them performing lots of work to strengthen other areas of the body that may not at first glance appear to involve the affected knee directly. But such an approach is with good reason. It turns out the health of the glutes, core, quads, and hamstrings is related to the ACL's health. You could call them the four bodyguards of the ACL. What's more, you don't have to sustain an ACL injury before you begin working to strengthen those other zones. There is plenty that you can proactively do today to make those bodyguards strong, so they can help prevent ACL and other knee injuries in the future.
Glutes – The muscles of the gluteus maximus together form the largest muscle group in the human body. With all that power behind them, the glutes have a role to play in just about all the lower body movements we engage in. When the glutes are healthy and well-toned, they work to stabilize the pelvis, abduct the hip, and rotate the thigh in an outward direction. When glute muscles are weak, however, thighs tend towards an internal rotation which is an abnormal position that puts increased stress on the knees and increases the risk for ACL injury.
Quads – Comprised of four separate muscles at the front of each thigh, the quadriceps attach to the kneecap. One of the most crucial jobs of the quads is to stabilize the knee joint. The quads are also excellent "shock absorbers" of the various impacts on the knee caused by everyday use or sports. Weak quadriceps muscles are clinically known to increase the risk of non-contact ACL injuries. Most people think of standard squats as the best way to strengthen the quads, but squats aren't the only option. Straight leg raises and wall sits are great exercises to strengthen the quads without putting undue pressure on the knees.
Hamstrings – While the quadriceps muscles come together at the front of each thigh, the hamstrings consist of three muscles at the thigh's back. The hamstrings also serve as protective knee stabilizers. Further, since the ACL works to restrain specific movements through the knee, the hamstrings act as the primary active restraint to those movements. In other words, strong hamstrings reduce knee injury risk by preventing the knee from moving too far forward or backward.
Core – Weak core muscles can result in a host of problems for the whole body, including the knees and the ACL. When the core is weak, it can cause the pelvis and hips to angle forward, thus forcing the knees to rotate inward. As previously explained, internal knee rotation is a significant risk factor for ACL injury. But there's good news! The ability to control bodily movements from a strong core can help relieve pressure and stress on the muscles surrounding the knees. While many people think of crunches when considering core exercise, there are many more activities to choose from. Planks and glute bridges are great alternatives to crunches and can help you keep activating your core by changing up the style of exercise you engage in.
Most people think ACL injuries are synonymous with elite athletes who play high-level sports, but that isn't true. Anyone, no matter their fitness level, can sustain an ACL injury. An abrupt stop on an otherwise uneventful jog around the block is enough to do severe damage. But you can help prevent injury by consistently showing some love to those muscles that support and protect your knees and your ACL. Keeping the ACL's bodyguards strong and ready is a powerful way to prevent knee injury now and well into the future.
Sources:
https://www.verywellhealth.com/acl-injury-prevention-strengthening-3120475
https://gonextlevelphysio.com/10-best-quad-exercises-for-bad-knees-from-experts/
https://nyulangone.org/news/five-ways-prevent-anterior-cruciate-ligament-injuries
https://parade.com/1335619/elizabethnarins/best-hamstring-exercises/