Should knee physiotherapy hurt? Is it really no pain, no gain?

Acceptable discomfort versus warning pain

Many physiotherapists use a simple pain scale from zero to ten. During exercise, discomfort up to around three or four out of ten is usually acceptable, especially for arthritis and tendon problems, as long as it settles quickly afterwards. Muscle fatigue and the burning feeling of a hard set are expected and are not a sign of harm.

Warning pain is different. It is sharp, catching or stabbing, it builds during the session, or it is felt at a specific point in the joint. Pain that leaves the knee more swollen, stiffer or more painful the next morning means the load was too much for the knee at that stage.

Why pushing through can backfire

Overloading a recovering knee usually causes more swelling, and swelling switches off the thigh muscles. The knee then feels weaker, so the next session goes badly, and the cycle repeats. After surgery, forcing bending or loading too early can also stress a repair or graft before it is ready.

The opposite mistake is just as common: avoiding all discomfort and never progressing. Tendons, muscles and cartilage adapt to load, and a programme that never challenges the knee rarely gets it back to sport or heavy work.

What to do if a session hurts

• Tell your physiotherapist which exercise hurt and where
• Reduce the weight, range or number of repetitions rather than stopping everything
• Use ice and raise the leg if the knee is swollen after the session
• Use the next-morning response to guide the following session

If pain is getting steadily worse over a couple of weeks, or the knee starts locking, giving way or swelling more, a review by a knee specialist is sensible. Seek urgent care for a hot, red, very swollen knee or fever after surgery.