Health Library / Training
This content is for education only and is not medical advice. I'm a fitness coach, not a physician. Talk to your doctor before starting any medication, hormone, supplement, or new exercise program, especially if you have a medical condition or take prescriptions.
"My doctor told me to stop squatting because of my knees."
I hear this constantly and it's usually a misunderstanding of something more specific that got said. Because the actual guidance for knee osteoarthritis, across the major bodies that issue it, puts exercise first. Not rest. Exercise is the recommended treatment, ahead of most things people reach for.
Osteoarthritis is the wearing of cartilage, the smooth surface letting your joint glide. It thins, the joint gets irritated, and it hurts and stiffens.
The old model was that it's purely mechanical wear — you get a set number of miles and using them up is your fault for being active. That's been substantially revised. Inflammation plays a part. Body weight plays a large part. And cartilage responds to loading — it's living tissue that depends on being compressed and unloaded to move fluid through it, because it has no blood supply of its own.
Which means the joint that never gets loaded doesn't stay pristine. It gets worse.
That's the reframe: motion is not the enemy of a knee. Being still is.
Worth saying because people carry guilt about this. Recreational runners do not show higher rates of knee arthritis than sedentary people — and in several analyses show lower rates. Elite and high-mileage competitive running is a different question. Your 20 miles a week is not what did this.
What genuinely raises risk: previous joint injury, particularly ACL and meniscus tears, body weight, genetics, and certain occupations with heavy repeated kneeling and lifting.
If you're carrying extra weight, losing some is the most effective thing available for knee pain. The forces through the knee in walking are a multiple of body weight, so a few pounds off is worth several pounds of load per step, and it compounds across thousands of steps a day.
I know that's the least welcome sentence in this module. It's also the one with the most behind it.
Quadriceps. Strong quads are consistently associated with better function and less pain in arthritic knees. This is the most direct, best-supported training target there is for this.
Glutes and hips. How your hip controls your thigh determines what your knee has to tolerate. Weak hips send the knee places it doesn't want to go.
Full range where you have it. The instinct is to work in a tiny, safe arc. That tends to give you a knee that only tolerates a tiny arc. Work the range you can control without a pain spike, and expand it over time.
Low-impact volume — bike, pool, rower — to accumulate work without pounding.
Depth is the usual sticking point. Rather than abandoning squats, most people do fine going to the depth that doesn't provoke it and building from there. Box squats give you a consistent stopping point. Leg press lets you load without balance demands. Split squats and step-ups load one leg at a time with less total joint stress, and they build the single-leg control that matters for stairs and hills.
Tempo over load — slower, controlled reps, lighter weight — is often the difference between a knee that complains and one that doesn't.
Warm up longer than you think you need. Arthritic joints are markedly better ten minutes in.
Sore during and better after is usually fine. Sharp during, or swollen and worse the next day, means back off. That's the feedback loop, and it's individual enough that no article can set it for you.
Deep loaded knee flexion under heavy weight. Running on hard surfaces, if that's a clear trigger for you. Adding load and volume at the same time. Ignoring a knee that's talking to you for a month.
See someone for: a knee that locks or catches, one that gives way, significant swelling — especially rapid swelling after an incident,
inability to bear weight, night pain that's severe, or any knee that's clearly getting worse over weeks rather than better.
If you've been diagnosed with osteoarthritis, a physical therapist is the right person to individualize this. Severity, which compartment, your other joints and what you actually want to do all change the answer, and a program built for you beats general advice by a wide margin.
A diagnosis of arthritis is not a sentence to stop training. It's a reason to train differently, and specifically a reason to get strong, because the quadriceps are doing the work your cartilage can't.
The people I've seen do worst with arthritic knees are the ones who stopped. Weaker quads, more weight, stiffer joint, more pain, less movement. That loop runs fast and it's the thing to stay out of.
Last updated September 30, 2026