If you are a runner, there is no doubt you have heard that running may be bad for your joints, and in particular the knees. Perhaps you are new to running and considering getting your running shoes out so that you can reap the many rewards associated with running, such as improved cardiovascular health or mood-boosting effects – to name a few (1).

However, perhaps you have read online, or have been told, that running isn’t actually very good for your joints or knees. Confused? Let’s break it down.

First of all, you are not alone if you have ever felt worried about running’s effects on your joint health – it’s a super common concern But the good news is that evidence tells us that running is largely beneficial for the joints (Hooray!)  

This myth was not pulled from thin air to stop runners from reaching the sought-after “runners high”, or to keep runners from skipping red lights at the pedestrian crossing to reach their PB on Strava (not recommended). But, based on the idea that running would put excessive load or pressure on the knee joint leading to the development of osteoarthritis.  

What is osteoarthritis? 

Osteoarthritis is the term used to describe degenerative changes within the joint. These changes are associated with increasing age, but other factors may influence its development. Just as our skin and our hair show signs of age, so do our joints. In the knee joint, the joint surfaces (cartilage) become less smooth, the joint space may narrow and the synovial fluid that helps with friction and hydrates the knee can become less viscous. This can lead to pain, stiffness and instability. As part of everyday life, our joints are exposed to constant low-level damage and our joints can go through stages of wear and repair, this is normal and not harmful. It is thought that in symptomatic osteoarthritis this repair stage is less effective (2). 

However, recent research has disregarded the myth that running causes osteoarthritis and indicates that those who recreationally run have a reduced risk of developing osteoarthritis compared to more sedentary (inactive) people. A study in 2017 showed that recreational runners who ran less than 25 miles per week had a 3.66% risk of developing osteoarthritis in comparison to sedentary individuals who had a risk of 10.23%, demonstrating the protective effects running may have on the joints (3). 

We should note that this study also looked at elite competitive runners (those who run for their country or professionally) and found they may have an increased risk of developing osteoarthritis at 13.3%. Although, to caveat this; from the study, it is hard to determine if this increase is due to the increased mileage, or due to the competitive nature of the sport leading to injury and driving the athletes to push through their injuries and pain to reach PB’s or win marathons (3). 

But exactly how would running protect our joints from osteoarthritis?

Well, it is thought that the stress or load that is placed on the joints when you run causes joint remodelling and the suppression of pro-inflammatory cytokines (cells that promote inflammation) improving the joint function and actually causing a reduction in tissue degenerative changes. Studies have also shown improved bone density, improved blood flow, better tissue extensibility and better mobility of the synovial fluid (4). 

Running may also help reduce pain in people who have osteoarthritis. 

The Osteoarthritis Initiative carried out a follow-up study on those who had already been diagnosed with osteoarthritis in their 50s. They found that those who followed a low-dose running programme had reduced knee pain and when they reviewed their x-rays there was no worsening structural progression of their knee joints. It is quite possible that as running helps to increase the strength of the lower limb muscles, this increased strength lessens the impact absorbed by the knee from the ground reaction force, lessening knee pain (5). 

The real factors that put you at risk for developing osteoarthritis are: 

Age – age above 50 years, with increased age comes increased age-related changes 

Sex – females have an increased risk of osteoarthritis particularly in the knee, it has been hypothesised that this is due to hormonal changes that occur in menopause. However, not confirmed. 

Strong family history- genetics may play a part

Previous injury and surgery – such as an ACL rupture and repair.

Obesity – increasing the systemic inflammation in the body and excessive load on the joints. 

Muscle weakness – as there is less support around the joints

Other joint conditions - rheumatoid arthritis or gout 

Perhaps it wasn’t osteoarthritis you were worried about…

Maybe you have a friend who took up running and then developed knee pain? This is all too common, indeed there is even a knee injury named after runners ‘Runner’s knee” also known as patellofemoral pain. This is indeed a common injury seen in runners, but it is not down to the act of running itself. We are born to run. Think back to our hunter/gatherer days when we would be running after our next meal. Running is what we were designed to do.  However, these days our joints and muscles are less prepared for the load associated with running as we move less and sit more.  With more sitting comes reduced muscle strength, imbalances and poor balance increasing our risk of an overload injury. For example, when we place stress on our muscles, joints or tendons with a new exercise, or progress too quickly with any exercise before our tissues have had time to adapt beyond what they have been conditioned to deal with, this can lead to injury (6,7).

So, now you know running moderately is a great form of exercise that is protective for your joints and may reduce your risk of osteoarthritis.

How can you do your best to prevent injury? 

Begin a beginner’s running programme – try the Couch to 5k, this will allow your body to adapt slowly to the demands that running places on the knees without overdoing it. 

Invest in a good pair of running shoes – whether you are street running or cross country running, invest in a good supportive shoe that is right for you.

Begin a strength programme to support your running – bridges, step-ups, lunges, dead bugs and squats would be a great start. 

Nutrition is key– underfuelling can increase your risk of injury 

Sleep – lack of sleep can increase injury risk by up to 1.7% (8)

Do not run every day – your body and collagen need time to repair following a run, ideally, wait 24 hours before your next run. 

Seek professional advice if you are in pain – if you do experience pain when you run, seek assessment from a physiotherapist.  A physiotherapist will be able to assess your running gait and check for any altered biomechanics that may be causing pain.