Arthritis and exercise: what to do, how much, and when to back off

A practical arthritis training plan: how many sets and reps per week, how to read pain on a 0-10 scale, and the signs that mean you should see a doctor.

An arthritis diagnosis still gets read as a ban on training, even though controlled loading is one of the best-supported parts of treatment. The gap is that nobody tells you how much, at what intensity, and what to do on the days it hurts. This covers exactly that, with numbers.

Osteoarthritis and rheumatoid arthritis are different problems

Osteoarthritis (OA) is cartilage breakdown plus changes in the bone underneath, most often in the knee, hip, thumb and spine. The pain is mechanical: worse after load, better with rest, and morning stiffness is short, usually under 30 minutes.

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease. It hits the small joints of the hands and feet, usually symmetrically, morning stiffness lasts over an hour, and the joint can be warm and swollen. RA is treated with medication prescribed by a rheumatologist, and training is an addition rather than a replacement. In OA, training itself is first-line treatment alongside body-weight control.

Why loading helps and rest backfires

Cartilage has no blood supply and feeds by diffusion, with synovial fluid moving in and out during cycles of loading and unloading. A joint that does not move gets fed less, and the muscles around it start losing strength after 7 to 10 days of full rest. A weak quadriceps means the knee absorbs a larger share of the force on every step, every stair descent and every time you stand up from a chair.

So the goal is the opposite of protecting the joint from work: enough load to make the muscle adapt, enough control that the joint is not overwhelmed. A realistic window for the first measurable change is 6 to 12 weeks of consistent work, not 10 days.

The weekly plan in numbers

Strength: 2 to 3 sessions per week

Knee extension or leg press through a pain-free range: 3 sets of 10-15 reps
Box squat or split squat, partial range to roughly 60-90 degrees: 3 x 8-12
Glute bridge or Romanian deadlift: 3 x 10-12
Quad isometrics for bad days: 5 holds of 45 seconds, 60 seconds rest between

Work at RPE 5-7 out of 10, leaving 2 to 3 reps in reserve at the end of each set. When you hit the top of the rep range in all three sets without symptoms worsening, add 2.5 to 5 percent load.

Cardio: 150 minutes per week

Five sessions of 30 minutes or three of 50. A stationary bike at low resistance and 70-80 rpm, swimming, and walking on flat ground are the easiest on knees and hips. If one long walk hurts, split it into 3 x 10 minutes a day. A daily target of 6,000 to 8,000 steps is a more sensible goal than the usual ten thousand.

Mobility and balance: 5 to 10 minutes daily

Two sets of 10 slow reps through whatever range you have, without holding a painful position. For knees and hips, add single-leg stands, 3 x 30 seconds per side, holding a support if you need one.

The pain rule: a 0-10 scale

Pain up to 5 out of 10 during exercise is acceptable if it settles back to your pre-workout level by the next morning.

Rate your pain from 0 to 10 before the session.
During work it may rise to 5, but not beyond.
If pain 24 hours later is higher than before, drop the load 10 to 20 percent next time or cut one set.
If swelling lasts more than 48 hours, replace that specific movement pattern rather than scrapping the whole session.

Adjusting when it hurts

Reduce range of motion before you reduce weight. Squatting to 60 degrees instead of full depth often solves it.
Swap impact for non-impact: running becomes cycling, jumps become sled pushes or fast uphill walking.
More short sets beat long sets taken to failure.
Warm up for 10 minutes before working sets; a warm joint tolerates more.
While a joint is warm and swollen, stay on isometrics and unloaded movement.

Body weight, food and sleep

During walking, the knee feels every kilogram of body weight as roughly three to four kilograms of force. For someone at 90 kg, losing 5 kg already makes a measurable difference, and the largest effects show up at around 10 percent body weight lost combined with strength training. A rate of 0.5 to 0.75 percent of body weight per week is plenty.

For protein, count 1.2 to 1.6 grams per kilogram per day, roughly 84 to 112 grams for a 70 kg person, spread across 3 to 4 meals of 25-40 grams. Oily fish twice a week and a vitamin D check are worth it, since deficiency is common at northern latitudes. Fewer than 6 hours of sleep for several nights in a row measurably lowers your pain threshold. No food cures arthritis; body weight and consistency do most of the work.

When to see a doctor

A red, warm, markedly swollen joint, especially with a fever. That can be an infection and needs urgent assessment.
Morning stiffness lasting over an hour in several small joints symmetrically, going on for more than 6 weeks. Rheumatoid arthritis needs ruling out, because early treatment changes the course of the disease.
The joint locks, catches, or gives way under load.
Pain wakes you at night or does not ease with rest.
Numbness, weakness, or loss of sensation spreading down an arm or leg.
No improvement at all after 12 weeks of consistent work.
Before taking anti-inflammatories regularly for more than a week or two, ask a doctor or pharmacist, especially with a history of stomach, kidney or blood pressure problems.

The short version

Strength train 2-3 times a week, 3 sets of 8-15 reps at RPE 5-7, plus 150 minutes of moderate cardio.
Pain up to 5 out of 10 is fine if it returns to baseline within 24 hours; if it does not, cut load by 10-20 percent.
Change range of motion and exercise selection first, weight second.
Losing 5 to 10 percent of body weight and eating 1.2-1.6 g of protein per kilogram daily work together with the training.
A hot red joint with fever, a locking joint, or symmetric morning stiffness over an hour is a doctor visit, not a gym session.