Knee osteoarthritis and training: what helps and what hurts

The doctor says osteoarthritis, and the first instinct is to walk less, squat less, do less of everything. That is the surest way to be worse off in six months. A knee you protect gets weaker and stiffer, and a weaker leg takes a bigger hit with every step.

Cartilage is not a tyre wearing down

The wear-and-tear picture of osteoarthritis is outdated and it sends people the wrong way. Joint cartilage has no blood supply; it feeds on joint fluid that only moves when the joint is loaded and unloaded in turn. Rest does not preserve a knee, it starves it.

Research generally shows that regular movement and strength training do not speed up joint damage. The effect on pain and function is not dramatic, but it is dependable and broadly comparable to what common painkillers deliver, with far fewer side effects.

The other surprise is that scan findings and pain match poorly. Plenty of people with marked changes walk about without trouble, and plenty with mild changes struggle out of a chair. An X-ray is not a verdict and it does not write your programme.

Thigh strength does the most work

The evidence is strongest for lower-body strength training, particularly the quadriceps and the hip muscles. A stronger quadriceps absorbs force that would otherwise go straight through the joint, and stronger hips show up as steadiness when you walk and when you come down stairs.

A workable frame: two to three sessions a week, five to seven exercises, two to three sets of 8 to 15 reps. Sit-to-stand from a chair, leg press, glute bridges, short-range lunges and hip abduction cover most of it. Resistance bands are enough equipment to start with if you have no gym nearby.

The load has to climb. Five weeks of the same reps with the same band gives the knee no reason to get stronger. Add a rep or a little tension each week, and give the programme 8 to 12 weeks before you judge whether it is working.

How much pain is allowed

This is the question that stops most people. A useful guide is a 0 to 10 scale: pain up to about 5 during the exercise is acceptable, provided it settles within an hour of finishing.

The real test is the next morning. If the knee is stiffer and sorer than the day before, you overshot — drop the weight or the number of sets by 20 to 30 per cent, but do not skip the session. If it feels the same or better, hold at that level.

What genuinely makes it worse

Flare-ups usually come from a jump in volume, not from exercise itself. Someone on 2,000 steps a day decides to do ten thousand from Monday, and by Friday can barely stand. The same applies to coming back to the gym after months off — the first six weeks need a plan rather than enthusiasm.

The second mistake is stopping completely at the first twinge. A few days on the sofa lowers the pain and the strength with it, so the next attempt is harder. The third is a programme built only from stretching and gentle movement — pleasant, but muscle does not grow from it.

Loaded deep squats pushed through sharp pain make no sense; nor does avoiding knee bend altogether. Cut the depth and the load instead of dropping the movement — knee pain in the squat usually has a fixable explanation, and the technique can be rebuilt from scratch even with arthritis.

Weight, walking and the things sold as solutions

For people carrying extra weight, losing 5 to 10 per cent of body mass usually brings a noticeable drop in pain, because the knee takes several times body weight with each step. Diet and strength training together work better than either on its own.

Twenty to thirty minutes of walking on most days is good, as long as the volume creeps up rather than doubles. A stationary bike on light resistance, with the saddle high enough to keep the knee from bending too far, suits sore days, and so does exercising in water.

A sleeve or brace makes some people feel steadier, but it does not change the joint. Evidence for supplements such as glucosamine and chondroitin is weak and inconsistent — if months of taking them have made no difference, there is no reason to persist.

When to see a doctor

Some signs are not for self-management. Get checked if the knee locks in one position or gives way underneath you, if it is hot, red and swollen alongside a temperature, or if severe pain started after a fall or a twist.

The same goes for pain that wakes you at night and does not shift when you change position, and for swelling that will not settle over several weeks. If three months of consistent strength work has changed neither pain nor function, that warrants a fresh assessment — not giving up on exercise.

The short version

• Rest does not protect the joint; leg strength is the best-supported way to cut pain and walk more easily.
• Two to three strength sessions a week, two to three sets of 8 to 15 reps, with the resistance going up over time.
• Pain up to 5 out of 10 during exercise is fine if the knee is no worse the next morning.
• Sudden jumps in step count or load cause flare-ups far more often than the exercises do.
• Locking, giving way, a hot swollen joint or pain after a fall all need a doctor.