Why do my knees hurt when I run?

Knee pain is one of the most common complaints among new runners, and in most cases it isn’t caused by running itself: it’s caused by doing too much of it too soon, or by weakness elsewhere that the knee ends up absorbing.

The knee is a hinge caught between the hip and the foot. When either of those isn’t doing its job, the knee takes the load. That’s why the fix usually involves changing something other than your knee.

The most likely cause: too much, too soon

Your heart and lungs adapt to running within weeks. Tendons, ligaments and cartilage adapt over months. That mismatch is the single biggest source of beginner knee pain: your fitness outpaces your structure, so you run more than your tissues are ready for.

Signs this is what’s happening: the pain came on gradually, it’s worse during and just after runs, it eases with rest, and it appeared shortly after you increased your running.

The fix is the least satisfying one available: do less for a while, then increase more gradually. Roughly ten percent more running per week is the usual guideline, and beginners frequently exceed it without noticing: adding a session, a week, and a longer interval all at once.

Runner’s knee

Pain around or just behind the kneecap, often worse going downstairs, sitting for long periods, or after a run, is commonly described as runner’s knee. It’s typically related to how the kneecap tracks in its groove, which is influenced by hip and glute strength more than by anything happening at the knee.

The most useful thing most beginners can do about it is strengthen their hips and glutes. Glute bridges, side-lying leg raises, and slow step-downs from a low step, done a couple of times a week, address the actual weak link.

Pain on the outside of the knee

A sharp or burning pain on the outer edge of the knee, often arriving at a predictable point in the run and easing when you stop, frequently relates to the iliotibial band, a thick band of tissue running down the outside of the thigh. It’s associated with hip weakness, sudden increases in mileage, and a lot of running on cambered surfaces like the sloped edge of a road.

Varying your route, avoiding always running on the same side of a cambered road, and the same hip and glute work all tend to help.

Things worth changing before anything else

Slow down. Impact forces increase with speed. Running at a genuinely conversational pace reduces load per stride considerably. See How slow should a beginner run?.

Take shorter strides. Overstriding, landing with your foot well ahead of your body, leg straight, sends impact straight up through the knee. Quicker, shorter steps with your foot landing closer beneath you is gentler.

Take rest days. Adaptation happens between runs, not during them. Running on consecutive days as a beginner is a common route to joint pain: see How many times a week should a beginner run?.

Check your shoes. Not the brand, the mileage. Worn-out shoes lose their cushioning long before they look worn out.

When to stop and get it checked

Take a break from running and see a physiotherapist or doctor if you have any of the following:

• Pain that makes you limp or alter how you walk
• Swelling around the joint
• The knee locking, catching, or giving way
• Pain that persists at rest or wakes you at night
• Pain that hasn’t improved after a week or two of reduced running
• Pain that arrived suddenly during a run rather than building gradually

Running through knee pain that fits any of these descriptions is how a few weeks off becomes a few months off.

The realistic timeline

Most beginner knee pain settles within a couple of weeks of reducing your running and adding some hip and glute strength work. You usually don’t need to stop entirely: often a shorter, slower session on softer ground is fine while things calm down. But if it isn’t improving, get someone to look at it rather than waiting it out.

This is general information, not medical advice. If you’re in pain, please see a doctor or physiotherapist, they can assess what’s actually going on in a way an article can’t.

Pace builds up gradually on purpose, with run/walk intervals that only become continuous running around week six and finish at a full 5K: the slow ramp that gives your joints time to catch up. Free to your first 5K. Try Pace.