Understanding how your nerves may affect/cause Achilles tendinopathy

Updated: Nov 13, 2019

We’ve written a lot in the past about all the different causes for Achilles tendinopathy in runners which include things like pushing your mileage too quickly, too many high intensity sessions and not allowing enough recovery time. These types of training errors usually cause a reactive tendinopathy where the tendon is very painful and irritated. But there’s a “silent” type of tendinopathy that has been baffling clinicians and researchers, because it seems to develop in even very sedentary individuals where there’s no training error that we can blame.



I say it’s a “silent” tendinopathy because these individuals usually don’t have any of the typical symptoms (like pain and stiffness) that we associate with Achilles tendinopathy in the more active population. Interestingly, it is also this group of patients who are much more likely to rupture their tendons.


In this article:

  • What causes a “silent” tendinopathy?

  • The role that increased neural tension plays

  • Do I need special tests for this?


What causes a “silent” tendinopathy?


In truth, we’re not entirely sure, but it appears that your peripheral nerves may have something to do with it. Your peripheral nerves in your legs run all the way from your lower back, down your legs and into the tips of your toes. One of the most well-known ones is the Sciatic nerve.



Besides their most obvious functions of controlling your muscles and relaying information about sensation to and from the brain, your peripheral nerves in your legs also control the blood flow to all your tissues (tendons, muscles, bones etc.) in your legs AND it influences the creation of new cells, restoration of injured tissue and the inflammatory processes.


Studies done on animals have shown that an injury to a peripheral nerve can negatively affect the strength and quality of the collagen in the connective tissue (a rat MCL in this case) below the level of injury. It also appears that people who have had sciatica in the past may be more susceptible to Achilles tendinopathy in the future. What this suggests is that an injury to the nerves that supply your Achilles tendon may cause some of the degenerative changes that we see in tendinopathies.


But Webborn points out that most people with Achilles tendinopathy have never had a clear injury to a nerve like with sciatica – he suggests that there may be a more subtle cause for these “silent” tendinopathies.



The role that increased neural tension plays


Our nervous system is continuous from our brains to the tips of our toes. As we move our limbs, our nerves in our legs (the peripheral nerves) are meant to slide freely. Sometimes they can get a bit stuck, causing them to be compressed and to be stretched when we move. When this happens we say that you have “increased neural tension” in your leg.


This compression can happen where the nerves exit the spinal canal or where they pass through tight muscles (in the buttocks for instance) and it is often of such a low level that you don’t even know that it is happening. Webborn suggests that, although this increased tension on the nerves may not always cause you pain at the level of the compression, it may influence how well the nerve functions below that level and can therefore be partly or wholly to blame for why people develop Achilles tendinopathy.


And this seems to hold true with what we see in our patients. Some of our patients will be runners with no sign of increased neural tension and whose Achilles tendinopathy can be solely contributed to training error. Others will be sports people where there appear to be a combination of training error and increased neural tension as the cause. And then we also see patients who don’t do any running or jumping sports, but when tested display clear signs of increased neural tension.


Do I need special tests for this?


No. X-rays, MRI scans and even nerve conduction studies cannot identify if you have increased neural tension in your legs because the changes are too subtle. But the good news is that it can easily be tested through performing a simple movement test called the SLUMP test.


When a physio gets you to perform the SLUMP test, they will ask you to move your body in a certain way and then note your flexibility as well as how your symptoms change during the movement. It’s a standard part of our initial examination process that we use for all our online patients at TreatMyAchilles.com


We also always test our patients’ spinal mobility and gluteal/piriformis flexibility because a stiff lower back and tight gluteal muscles can contribute to this problem. Your treatment plan will, more likely than not, include exercises aimed at improving your lower back’s flexibility and the ability of the nerves to move freely in your legs as well as your specific Achilles strength training programme.


Let me know if you have any questions. Need more help with your Achilles injury? You’re welcome to consult us online via video call for an assessment of your injury and a tailored treatment plan.

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. Ackermann, P. W. (2013). "Neuronal regulation of tendon homoeostasis." International journal of experimental pathology 94(4): 271-286.

  2. Maffulli, N., et al. (1998). "Achilles tendon rupture and sciatica: a possible correlation." British Journal of Sports Medicine 32(2): 174.

  3. Webborn, A. (2007). "A neuropathic model to the etiology and management of Achilles tendinopathy."

Subscribe to our mailing list!

For weekly Achilles tendinopathy updates

Contact

Email:

contact@treatmyachilles.com

Phone:

Legal Stuff

Treatmyachilles.com is owned by ML Physio Ltd. (England No. 7434251) trading as Treat My Achilles. Registered office: 4 Frederick Terrace, Frederick Place, Brighton, East Sussex, BN1 1AX

© 2018 by ML Physio Ltd.