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Achilles tendon pain – what surfaces are best to run on?

I find that the first instinct of an injured runner is often to switch to running on soft surfaces. Interestingly, the research has found that this may not be the best option when you have an injury like Achilles tendinopathy or tendonitis.



In this article:

  • Quick recap on how the Achilles works

  • Why softer surfaces may cause trouble

  • What running surface is best when you have Achilles pain?

Like to watch rather than read? Here's a video where I explained this:



Quick recap on how the Achilles works


Your Achilles tendon acts like a spring when you run and walk. When you land it absorbs and stores the force from the landing (this can be up to 6 times bodyweight) and then it releases this force back into the ground and propels you forward.


The Achilles obviously can’t do this on its own and works closely with the calf muscles as well as the rest of the leg. The calf muscles and Achilles tendon combined produce about 50% of the force that propels you forward!


Why softer surfaces may cause trouble


What the research is showing is that running on soft surfaces like track and sand increases your risk of developing Achilles tendinopathy. In contrast, running on hard surfaces like asphalt seems to have a small protective effect on your Achilles tendon.


One of the biomechanical properties that scientists measure when they analyse runners is how much stiffness they have in their legs when they run. Think about the whole leg as a spring. The “stiffer” the spring, the more energy it can store and release and essentially the better it can propel itself forward.


If you bounce a “stiff” spring on a hard surface it will find it very easy to bounce. The softer the surface, the more energy is lost into the ground and the harder you have to throw the spring to get it to bounce at the same height.


What researchers have found is that when a person runs on soft surfaces they adapt their running style to try and increase the stiffness in their legs (their springs) to make up for the energy that is lost to the softer surface. They do this by contracting their muscles more forcefully and keeping their joints stiffer and not allowing their joints to move through such a big range of movement. This happens automatically - your brain does this without thinking about it.



Researchers think that this increased muscle action and joint stiffness (due to running on a soft surface) places more strain on the Achilles tendon, causing it to sustain more micro-damage. In the case of running on sand, I would also argue that the Achilles will have to work through a much larger range of motion (because you tend to sink into sand) which may also lead to more micro-damage.


What running surface is best when you have Achilles pain?


From the discussion above it would seem that you may be better off running on hard surfaces like tarmac when you have Achilles pain. I would, however, always advise to also experiment and find your own best surface. Our bodies are all different and our injuries are also all different. If your Achilles feels better when you run on slightly softer surfaces, then go for it.


Let me know if you have any questions. Need help figuring out a treatment plan for your Achilles pain? Check out our online service for treating Achilles tendinopathy/tendonitis.

Best wishes

Maryke


About the Author:

Maryke Louw is a chartered physiotherapist and holds an MSc in Sports Injury Management. You can follow her on LinkedIn, Facebook, Twitter or Instagram.




References:

  1. Knobloch K, Yoon U, Vogt PM. Acute and overuse injuries correlated to hours of training in master running athletes. Foot & ankle international 2008; 29(7):671-76.

  2. Lorimer AV, Hume PA. Achilles tendon injury risk factors associated with running. Sports Medicine 2014; 44(10):1459-72.

  3. Willy RW, Paquette MR. The Physiology and Biomechanics of the Master Runner. Sports medicine and arthroscopy review 2019; 27(1):15-21.

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