Why do my knees hurt when I run?
According to Sports Medicine Australia, 42% of all running injuries occur on the knee. Today, let’s look at why knee pain can be common, why it might be a technical issue, and how we can correct it.
Knee pain can be a complete nightmare, at times it is unpredictable or affects life outside of your running and workouts. Why are the knees so much more often than the hip and ankle? Well, try to think of the knee as the unlucky middleman. Above is the hip, and below are the foot and ankle. Often technical or biomechanical discrepancies at either of the three joints can cause excess stress and friction at the knee. It takes a load of the load for its two best friends.
- The overstride.
- Rotation control.
- Training load and lifestyle.
- Previous medical History
The Overstride
If you overstride, it simply means you are landing in front of your centre of mass creating braking forces. Imagine you are sprinting with perfect technique and are asked to come to a stop as quickly as possible. Naturally, you will shorten your steps and start to dig your heels into the ground in front of you with each stride until you stop – it’s stressful and takes significant effort. When overstriding this is happening on a smaller scale every stride. It will also usually occur with a straight leg, particularly at the knee joint. Overstriding can increase the forces going through your kneed by up to six times your body weight – if you do this repetitively, your knee is likely to break down due to the repetitive overload of force. Compound that with a relatively straight leg on landing means your muscles are not functioning at the right range to attenuate the force. Imagine your quad is like a spring, if your leg is straight the spring is fully compressed. It is no longer in a good position so absorbs force which will worsen the impact of the overstride. If you run repetitively with these braking forces, your knees will hurt. Once you control that overstride and improve your technique, stress on the knee and body overall will be significantly reduced.
Rotation Control
The knee joint is a simple hinge joint in the sense of movement and running. It has muscles that cross the joint which allows you to powerfully contract it in two directions – forward and backward. It has ligaments within the joint to make sure that forwards and backwards motion doesn’t go too far – the anterior and posterior cruciate ligaments. Two external ligaments that make sure it doesn’t move medially or laterally at all! The medial and lateral collateral ligaments. This brings me to what is called valgus stress. If you picture a person staring up, and you get on the outside of their knees and push them together (inwards), this is valgus stress. It is awful for the knee and the medial collateral ligament is there to resist this stress. Enough of the anatomy, the knee does not like rotational forces, and when analysing runners on video, those who have a lack of rotation control tend to fall in at the knee. From the frontal or posterior view, you will see an apparent rotation at the hips, then on landing that load continues into the knee causing quite a nasty valgus stress. With repetition, this will often lead to medial (inside) knee pain and can cause long-term cartilage damage. Ouchie! But this again can be rectified. Is it a strength issue? Are your lateral hip muscles and core not currently strong enough to halt that momentum when you land? If so, hip strength and control through an exercise programme will correct it. Alternatively, is it a purely habitual movement issue? Once you see it on video and have some corrective technical coaching, that body will be moving in straight lines again as you build stronger more technically minded habits.
Training Load and Lifestyle
This is a much more simple explanation for knee pain. Are you running too much? Are you running too slowly? Is your training programme right for you? Do you do any strength work?
Are you just overloading yourself? Injury can come in the form of overtraining and not giving the body time to recover before repeat efforts. Refer to last month’s blog on overtraining and familiarise yourself with the symptoms. Overload will also come in the form of excess time on your feet while running slowly. This is possible if you only run a certain distance (usually 5-10km) at the same pace three plus times per week. This builds a lot of time on the ground particularly if you are running slowly. As we have said many times in our blogs – faster running means less ground contact time, means less load through your body. Do you have enough hills and intervals in your programme? Adding hills will improve leg strength and reduces the impact on the knee. Running faster intervals reduces the time load through your knees, and you are likely to be running with a better technique when focusing on speed. Are you storing? You can do the perfect running programme but at the end of the day, joint and tissue resilience comes from strength. There are plenty of remedial exercises that do not take long and will prime your knees for running. Please don’t skip the strength!
Previous Medical History
The title says it all. In sports the highest predictor of injury is……… Previous injury history. If you had an accident or a trauma on your knees in the past, it is likely you will encounter some kind of knee pain when running. But it’s about managing your lifestyle and running if that’s what you love. I encourage you to get some help, start slow, walk run, get a strength programme and build up to a consistent and manageable amount of running that fits your lifestyle. Happy running!
Recap
- Oversteering significantly increases stress in your body.
- Knees like to go forwards and backwards – control that rotation
- How often and what type of running do you do? Is this contributing to your pain?
- If you have a history of knee trauma, get some advice, and then run!
If you want to find out more about how you move, where your strengths and weakness lie, then our Foundation Running Assessment would be an ideal why to move forwards and help you get to the bottom of your problem.