Why Does My Knee Hurt When I Run?

Why Does My Knee Hurt When I Run?

Knee pain is one of the most common running injuries — and one of the most frustrating. The good news? Most knee issues are fixable with the right load management and strengthening.

Common Causes of Knee Pain in Runners

• Runner’s Knee (PFPS): Pain around the kneecap caused by overload or poor patella tracking.

• ITB Syndrome: Pain on the outside of the knee from repetitive friction and compression.

• Patella Tendinopathy: Pain under or below the kneecap, often worse on stairs or hills.

• Training Load Errors: Sudden increases in mileage, speed, or hills.

How to Self-Assess Your Knee Pain

Ask yourself:

• Does it hurt at the start, ease off, then return later?

• Is downhill running worse?

• Is sitting for long periods uncomfortable?

• Does it hurt at rest?

• Is the pain sharp or more of an ache?

  
  

These patterns help identify the specific issue.

Should You Run Through Knee Pain?

Mild discomfort that warms up is usually okay. Sharp, escalating pain is not. Typically I would look at it as a ‘Traffic Light System’

• Green 0-1/10 is ok

• Amber 1-4/10 is acceptable

• Red 5+/10 and rising is not acceptable

This traffic light system can be thought of as a way of measuring pain both during the exercise and for the following 24 hours.

Simple Strengthening That Helps

• Leg extensions

• Step-downs

• Split squats

• Glute strengthening

• Slow tempo squats

Start with bands or bodyweight and build gradually.

When to See a Physio

If knee pain changes your running form or lasts more than 2–3 weeks, get assessed.

Pain that makes you limp can create compensation patterns and injuries.

If you’re a runner in London looking for help with knee pain, you can book an assessment with me here.