I find that the first instinct of an injured runner is often to switch to running on softer surfaces. Interestingly, the research has found that this may not be the best option when you have an injury like Achilles tendinopathy or tendonitis. Remember, if you need more help with an Achilles injury, you're welcome to consult one of our team via video call.
The terms tendinitis, tendonitis, tendinosis, and tendinopathy mean the same thing for all practical purposes, and we use these interchangeably in most of our articles.
In this article:
Like to watch and listen rather than read? Here's a video where I explain this:
Quick recap of 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 your body weight), 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 athletic tracks 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, keeping their joints stiffer, and not allowing the 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 you to 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.
How we can help
Need more help with your Achilles injury? You’re welcome to consult one of the team at TMA online via video call for an assessment of your injury and a tailored treatment plan.
We're all UK Chartered Physiotherapists with Master’s Degrees related to Sports & Exercise Medicine. But at Treat My Achilles we don't just value qualifications; all of us also have a wealth of experience working with athletes across a broad variety of sports, ranging from recreationally active people to professional athletes. You can meet the team here.
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.
Comments