Most ACL tears happen with nobody else around: a landing, a hard stop, a cut. That's good news for adults who still play, because the things that protect the knee can be trained.
Ask anyone who has torn an ACL how it happened and you'll hear a version of the same story. They weren't tackled. Nobody fell on them. They came down from a rebound, planted to change direction, or caught an edge on the last run of the day, and the knee just went. A pop, a lot of swelling, and a long year ahead.
That story is the norm, not the exception. The majority of ACL tears are non-contact injuries. The knee gives out during a movement the person has done thousands of times before. That sounds scary, but I read it the other way. If most of these injuries don't come from someone crashing into you, then most of what causes them is under your control. That's where ACL injury prevention exercises come in, and it's why I think every adult who still plays something should be doing them.
When people hear "ACL," they picture a high school soccer player or a college point guard. Those athletes do carry high risk, and that's where most of the research has been done. But I work with a lot of adults in their 40s, 50s and 60s who are still competitive about something: a Tuesday night volleyball league, pickleball four mornings a week, a men's soccer league, the annual ski trip out to Colorado. Those are cutting, landing and twisting sports, and the people playing them usually have a decade or two of desk work between them and the last time they trained for it.
That gap is the problem. Your skill stays. You still know where to be and when to move. What fades, unless you work to keep it, is the strength and reaction speed that let your knee handle a hard stop. You play like you're 30 on a body that has been sitting for 20 years. That's a setup.
The ACL's job is to keep your shin bone from sliding forward and twisting under your thigh bone. It gets into trouble in a fairly predictable position. You're landing, stopping or cutting, the knee is close to straight, and it collapses inward while the foot stays planted. Coaches call that inward collapse knee valgus. Picture the knee caving toward the other leg as you land.
In that position, the muscles that should be absorbing the force aren't doing their share, so the ligament takes it. The hamstrings are a big part of this. They pull the shin back and help protect the ACL, and in a lot of adults they're weak compared to the quads. Add tired legs late in a match, slower reactions, and a foot that's stuck to the court or locked in a ski binding, and you have the recipe.
None of this means you're fragile. It means the parts of the system that protect the ligament can be trained, and most people have never trained them on purpose.
The best evidence comes from structured warm-up programs built for soccer and other cutting sports, the FIFA 11+ being the best known. They combine strength work, balance, landing practice and change-of-direction drills, and they take about 15 to 20 minutes. Across many studies, teams that did them consistently had meaningfully fewer ACL injuries than teams that didn't, often around half as many.
Two details in that research matter more than the headline. First, the benefit depended on doing the program regularly. Teams that did it now and then got much less out of it. Second, the programs that worked weren't stretching routines. They taught people to land and cut well, and they built strength in the muscles that control the knee. That's the part most adults skip.
Most of those trials used younger athletes, so I won't pretend we have the same precision for a 52-year-old pickleball player. But the mechanics of the injury don't change with age, and adults have more to gain from the strength side because they've lost more of it.
When an adult who plays a cutting or landing sport comes to me, these movements show up in their program in some form. The exact version depends on their history, their knees and what they play.
You'll notice none of that is exotic. That's the point. ACL injury prevention isn't a special category of training. It's good lower-body strength work plus deliberate practice at the exact movements that hurt people: landing and stopping. I've explained [why squats aren't the enemy of your knees](/blog/no-squats-arent-bad-for-your-knees), and the same logic holds here. Loading the knee well makes it more durable, not less.
The landing and stopping drills are where coaching earns its keep. Most people can't feel their own knee caving in. Watching someone land from the front, or filming it on a phone, usually shows the problem within the first few reps. Once you can see it, it's very fixable.
You don't need to live in the gym. Two strength sessions a week that include single-leg work and hamstrings, plus five or ten minutes of landing and deceleration practice before you play, covers most of it. Do the harder sessions on days you aren't playing, and keep the pre-game piece short and sharp so it warms you up instead of wearing you out.
Effort matters too. These sets should be challenging, not a light circuit you breeze through. I use the [RPE scale](/blog/rpe-scale-explained) with clients so we're both honest about how hard a set actually was. For most adults, that means pushing a little harder than they're used to on the strength work and being a lot more careful than they're used to on the jumping.
And start before the season, not during it. If your league starts in January or the ski trip is in February, the time to build this is now. Six to eight weeks of consistent work changes how your legs handle a hard landing. Two weeks of cramming doesn't.
The reason to do any of this is so you get to keep doing the thing you love. I'd rather you spend an hour or two a week building legs that can take a bad landing than spend a year rehabbing a reconstruction. Plenty of the adults I train around Affton and South County are playing harder at 50 than they did at 35, and it's because they stopped treating the sport as their training and started training for the sport.
If you want a plan built around your sport, your knees and your schedule, that's exactly what we build in [personal training](/services/personal-training).
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