Training With Knee Pain

Knee pain is one of the most common reasons people cut back on training or quit it altogether. Yet for many knee conditions, properly dosed exercise is not a threat but a treatment. The editorial team explains how to tell overload from a serious injury and how to adapt training.

Where knee pain comes from

The knee joint bears a significant share of the load during squats, lunges, running, and jumping, so pain in it is one of the most common complaints among people who play sports. The causes vary widely, and it is precisely the cause that determines which training approach to choose.

In young active people, patellofemoral pain is most common — unpleasant sensations at the front of the knee, around or under the kneecap, that worsen with squatting, going down stairs, or sitting for a long time with bent knees. The second most common is patellar tendinopathy, “jumper's knee,” with pain below the kneecap.

In older people the issue is more often osteoarthritis — gradual changes in cartilage and bone accompanied by pain, morning stiffness, and reduced mobility. Acute injuries stand apart: damage to the menisci and ligaments, which usually has a clear moment of onset.

For practice it is important that most chronic knee conditions related to overload are linked to an excessive or too sharp increase in load, rather than to “wrong” movement as such. That is why the first step is always to analyze what has changed in training over the past weeks.

Warning signs: when you need a doctor

An acute injury with a characteristic mechanism — a twist on the planted leg, a blow, a crunch followed by rapid swelling — requires examination by a doctor. Such symptoms may indicate damage to the anterior cruciate ligament or the meniscus.

• rapid knee swelling within a few hours of the injury;
• a sensation of the joint “giving way” or being unstable;
• locking — the inability to fully straighten or bend the leg;
• the inability to put weight on the leg;
• redness, heat of the skin over the joint, an elevated body temperature;
• pain that does not decrease over several weeks despite reduced load.

Redness and heat over the joint combined with fever may indicate an infectious process that requires urgent medical care. Such a condition should not be self-treated with ointments or warming.

But if the pain arose gradually, without an injury, worsens during certain exercises, and is not accompanied by warning signs, it is usually a condition that responds well to load correction and exercise. Still, it is better to establish the exact diagnosis with a specialist.

Can you squat if your knee hurts

A common myth holds that deep squats “destroy” the knees. A review by Hartmann, Wirth, and Klusemann on the load on the knee joint and spine at different squat depths concluded that in healthy people, deep squats with proper technique do not increase the risk of knee injury compared with shallow ones.

It is another matter when the knee already hurts. Then depth, tempo, and weight become variables you can manage. Pain at the front of the knee often worsens within a certain range of flexion; temporarily limiting the range to a pain-free or mildly painful one lets you keep training.

Useful options: box squats with a controlled height, squats with the weight in front of the body (goblet), leg presses in a limited range, and isometric holds. For patellar tendinopathy, physical therapy often uses isometrics and slow heavy exercises with gradual progression.

The 2018 consensus on patellofemoral pain (Collins et al.) recommends exercise as the basis of treatment, especially a combination of exercises for the hip and gluteal muscles. In other words, “not squatting at all” is rarely the best path.

Training with knee osteoarthritis

In osteoarthritis, many people intuitively reduce movement, fearing they will “wear out” the joint. Yet international guidelines — in particular the 2019 OARSI guidelines and those of the American College of Rheumatology 2019 — name physical exercise as one of the key methods of treating knee osteoarthritis.

A Cochrane review by Fransen and colleagues showed that therapeutic exercise reduces pain and improves function in knee osteoarthritis. The effect is comparable to that of painkillers, but without their side effects.

An optimal program usually combines strength exercises for the thigh muscles, low-impact aerobic activity (cycling, swimming, walking), and balance exercises. Excess body weight is an additional factor of load on the knees, so reducing it often complements training.

Pain during and after exercise in osteoarthritis does not always mean harm. In many programs, moderate pain that passes within a day is considered acceptable. But if pain and swelling increase, the load must be reduced and discussed with a doctor.

Prevention and load management

The most effective preventive measure is gradual progression. A sharp increase in squat volume, adding jumps or running after winter, switching to a new program with a large volume of leg work — these are typical triggers of knee pain.

Strength of the thigh and pelvic-girdle muscles increases the knee's tolerance to load. Regular work on the quadriceps, hamstrings, and gluteal muscles is not only a path to better results but also a form of prevention.

The warm-up before heavy work should include a gradual build-up to the working weight in the same exercise. Neuromuscular warm-up programs developed for team sports have demonstrated a reduction in knee injury rates, particularly in football.

It also helps to monitor overall fatigue: after a hard week, technique breaks down more often, and the knee “loses” stability. Deload weeks and quality sleep are part of injury prevention.

Editorial conclusions

Knee pain in people who train is most often related to overload: patellofemoral pain, patellar tendinopathy, and, in older age, osteoarthritis. Acute injuries with swelling, instability, or locking require examination by a doctor.

In most chronic cases complete rest is not needed. Managing range, weight, and tempo, exercises for the hip and glutes, and gradual progression form the basis of current recommendations.

In osteoarthritis, exercise is a treatment, not a threat to the joint. The program should be built together with a physical therapist, taking into account the knee's response the next day.

We also recommend our articles on training with a shoulder injury, on training after 50, and on how to train after a break.

References

1. Collins NJ, Barton CJ, van Middelkoop M, et al. 2018 Consensus statement on exercise therapy and physical interventions (orthoses, taping and manual therapy) to treat patellofemoral pain: recommendations from the 5th International Patellofemoral Pain Research Retreat. Br J Sports Med. 2018;52(18):1170–1178.
2. Hartmann H, Wirth K, Klusemann M. Analysis of the load on the knee joint and vertebral column with changes in squatting depth and weight load. Sports Med. 2013;43(10):993–1008.
3. Bannuru RR, Osani MC, Vaysbrot EE, et al. OARSI guidelines for the non-surgical management of knee, hip, and polyarticular osteoarthritis. Osteoarthritis Cartilage. 2019;27(11):1578–1589.
4. 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 Care Res. 2020;72(2):149–162.
5. Fransen M, McConnell S, Harmer AR, et al. Exercise for osteoarthritis of the knee: a Cochrane systematic review. Br J Sports Med. 2015;49(24):1554–1557.
6. Malliaras P, Cook J, Purdam C, Rio E. Patellar tendinopathy: clinical diagnosis, load management, and advice for challenging case presentations. J Orthop Sports Phys Ther. 2015;45(11):887–898.