Training with knee pain: what to change, what to keep
Keep training, change the dose. A Cochrane review of 54 trials found land-based exercise gives a moderate reduction in knee osteoarthritis pain that lasts months after the programme ends[1], and the 2019 rheumatology guideline recommends it strongly[2]. Reduce depth, load and speed rather than removing squats, accept mild pain that settles within a day, and see a doctor for a knee that locks, gives way or swells.
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First, rule out the things that need a doctor
Most knee pain around training is a load problem, not an injury, but a few presentations are not and should be seen rather than trained through. A knee that gave way, locked, or swelled quickly after a specific incident; a knee that is hot and swollen with no obvious cause; pain that wakes you at night; or any inability to bear weight — these belong to a doctor first.
Everything below assumes the ordinary case: an ache at the front of the knee on stairs and squats, or a stiff, grumbling joint that is worst for the first few minutes of moving. That case has a well-studied answer, and the answer is not rest.
Exercise is the treatment, not the risk
For knee osteoarthritis this is about as settled as clinical evidence gets. A Cochrane review pooling 54 trials and 5,362 participants found that land-based exercise produced a moderate benefit for pain, equivalent to a reduction of 12 points on a 0–100 scale, with the improvement still present two to six months after the supervised programme ended[1]. The 2019 American College of Rheumatology guideline gives exercise its strongest recommendation for knee, hip and hand osteoarthritis[2].
Patellofemoral pain — the ache behind or around the kneecap that is common in younger and more active people — is managed the same way. Clinical guidance puts exercise therapy, targeting the muscles of the knee and hip, as the first-line treatment[5].
The instinct to stop training until the knee stops hurting usually makes things worse, because a deconditioned quadriceps is less able to absorb load and the knee gets more sensitive, not less.
Are squats bad for your knees?
No. Squatting is a fundamental human movement and a loaded squat is one of the better ways to build the quadriceps strength that protects a painful knee. What a sore knee usually needs is not the removal of the movement but a change to its dose.
- Depth. Shallower squats reduce the load across the kneecap. Work in the range that does not provoke pain and extend it as it becomes comfortable.
- Load and volume. Lighten the bar and keep the sets. A lighter set that you can do pain-free trains the muscle; a heavy set you abandon trains nothing.
- Speed. Slow the descent. Control removes the impact spikes that provoke an irritable joint.
- Choice of exercise. Leg press, split squats, step-downs and leg extensions in a tolerable range all build the same muscle, so if one hurts, another usually does not.
A useful rule used in rehabilitation is to accept mild pain during the session that settles within twenty-four hours, and to reduce the dose if it does not. Pain that climbs session after session means the dose is too high, not that the exercise is wrong.
What body weight does to a knee
The knee is a joint where body mass shows up mechanically. In a study of overweight older adults with knee osteoarthritis, each kilogram of weight lost reduced the load on the knee by roughly four kilograms per step[3]. The arithmetic of walking makes that multiply into something large over a day.
The IDEA randomised trial then tested the combination: among overweight and obese adults with knee osteoarthritis, intensive diet plus exercise aiming for a loss of at least 10% of body weight produced less pain and better function at eighteen months than either diet or exercise alone[4]. Combined beat both single arms — which is the practical instruction for anyone carrying extra weight and a sore knee.
A week that works around a knee
Two or three strength sessions covering the quadriceps, the hamstrings and the hip muscles, each in a range that does not provoke pain, plus walking, cycling or swimming for the aerobic side. Cycling is often the kindest option early on because the range is controlled and the impact is close to zero.
Give it twelve weeks before judging it. Strength adaptations and the sensitivity of an irritable joint both move on that timescale, not on a fortnight. If you are also eating in a deficit, the guide on how fast you can safely lose weight covers the rate that is sustainable alongside training, and does exercise earn back calories explains why the sessions you add should not be eaten back twice.
Sources
- Fransen M, McConnell S, Harmer AR, Van der Esch M, Simic M, Bennell KL. Exercise for osteoarthritis of the knee. Cochrane Database of Systematic Reviews 2015;1:CD004376. ↩
- Kolasinski SL, Neogi T, Hochberg MC, et al. 2019 American College of Rheumatology/Arthritis Foundation Guideline for the Management of Osteoarthritis of the Hand, Hip, and Knee. Arthritis & Rheumatology 2020;72(2):220–233. ↩
- Messier SP, Gutekunst DJ, Davis C, DeVita P. Weight loss reduces knee-joint loads in overweight and obese older adults with knee osteoarthritis. Arthritis & Rheumatism 2005;52(7):2026–2032. ↩
- Messier SP, Mihalko SL, Legault C, et al. Effects of intensive diet and exercise on knee joint loads, inflammation, and clinical outcomes among overweight and obese adults with knee osteoarthritis: the IDEA randomized clinical trial. JAMA 2013;310(12):1263–1273. ↩
- Dutch multidisciplinary guideline on anterior knee pain: patellofemoral pain and patellar tendinopathy, 2024. ↩