Updated: May 27
The best night splint for Achilles tendonitis is no night splint at all. In this article, we explain why some people think that a night splint for Achilles tendonitis is a clever idea, why this may not be the best option, and what you should do instead to recover from your Achilles tendon injury. 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 our articles.
In this article:
We’ve also made a video about this:
Why do people recommend night splints for Achilles tendonitis?
One of the more common symptoms of Achilles tendonitis is a stiffness and/or pain in the injured tendon when people get up in the mornings.
A night splint or a Strassburg sock is something that holds your foot in a neutral (like when you’re standing) or pulled up position (like when you’re stretching a calf muscle) while you sleep.
The thinking is that holding your foot in this position keeps the Achilles tendon slightly stretched overnight so that it will not feel so stiff when you get up the next morning.
There is a scary myth going around that when you get out of bed and walk around on the stiff tendon, you are tearing little bits of your tendon. This is simply not true. Believe me, you will know it if you’re tearing your Achilles tendon. Here’s an article that busts this myth and that covers the issue of Achilles tendon stiffness and pain in the mornings more thoroughly.
What happens inside an injured Achilles tendon while you sleep?
A healthy Achilles tendon is made up of collagen fibres arranged parallel to each other. The fibres are arranged in bundles, also parallel to each other. This configuration is what makes a tendon much stronger than the sum of its parts, same as with a cable or rope.
When you have Achilles tendonitis, it's not every bundle and every fibre that is affected; usually it’s only a small portion of the tendon.
If we look at the injured part of an Achilles tendon under a microscope, we see that the collagen fibres are now somewhat disorganised, i.e. they are not nicely in parallel anymore, and there’s some extra fluid in between the fibres. This means that that part of the tendon is not as stiff and healthy as the rest of it.
Also, the injury causes some chemicals to be released inside the tendon (this happens in all injured tissue) that can irritate your nerve endings there if there’s too much of it.
When you sleep, you don’t move about as much as when you’re awake, which means that your circulation slows down. Therefore, the fluid and chemicals in the injured part of the tendon are not being flushed out as efficiently as during the day. This is why you may feel stiffness and/or pain in the tendon when you wake up and start moving about.
However, as you move around and your circulation gets going during the day, the fluid and chemicals inside the injured part of your tendon get processed better than when you were asleep, and the stiffness and/or pain you experienced first thing in the morning goes away or decreases.
Some people just feel stiffness. Some people just feel pain. Some people experience both. And others don’t have this at all. How long this lasts also differs from person to person; it can be from a few seconds to most of the day. Please note that the duration and severity of these symptoms are not indications of how bad your Achilles tendonitis is.
Why we don’t prescribe night splints
Firstly, the splint is actually holding your foot in a more stationary position while you sleep than it would be otherwise, so your circulation is even less able to carry away the fluid and chemicals in the injured part of your tendon.
A night splint for insertional Achilles tendonitis, which is a tendonitis occurring where the tendon attaches to the heel bone, can be quite irritating. Putting your foot in a stretched position would compress the injured tendon closer to the heel bone, which is somewhat like constantly prodding a bruise. If anything, this will cause even more discomfort in the morning.
Also, when we look at the research into night splints, there’s no good evidence to show that these things help.
Studies that compared them with some of the more conventional exercise-based treatments for Achilles tendonitis, such as calf raises or eccentric calf raises, found that when the night splits were added to those exercise regimes, there was no difference between the results for the patients who wore night splints and those who didn’t. A recent review of the research on night splints concluded that clinicians should not use night splints as treatment for mid-portion Achilles tendinopathy.
What to do instead of wasting your money on a night splint
So, buying a night splint for your Achilles tendonitis is a waste of money. What should you do instead?
The treatment approach for Achilles tendonitis that is best supported by the research has two components: relative rest and making the tendon more robust with rehab exercises.
Relative rest helps to maintain your injured tendon’s current strength, whereas prolonged periods of complete rest can actually cause its strength to decrease. As opposed to complete rest, relative rest means finding that sweet spot of an activity level that allows you to do as much as possible without making your pain worse.
Any pain you experience during an activity should not go above “niggle” level. Sometimes, injured tendons don’t complain while you’re doing an activity, only to flare up later that day or even the next day. So it’s important to also monitor your tendon’s 24-hour response to any activity that you do, whether it’s rehab exercises (see below) or going about your normal day-to-day business.
Here’s an article with more detailed advice on how to use pain to guide your activity levels.
Rehab exercises for Achilles tendonitis
The second part of this treatment approach is to make your Achilles tendon more robust.
You do this with strengthening exercises such as heel raises that get progressively more difficult as your tendon gets stronger.
The difficulty level at which you begin will depend on how strong the tendon is at that stage and on what it can tolerate based on the relative rest principle explained above.
Which difficulty level and what types of exercise you will eventually progress to will depend on what your aims and abilities are. The endgame for someone who just wants to walk their dogs will obviously be different from that of, say, a professional basketball player.
We have made a playlist of YouTube videos about exercises for Achilles tendonitis, if you are interested to know more.
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
Van Der Vlist, A. C., et al. (2021). "Which treatment is most effective for patients with Achilles tendinopathy? A living systematic review with network meta-analysis of 29 randomised controlled trials." British Journal of Sports Medicine 55(5): 249-256.
Martin, R. L., et al. (2018). "Achilles Pain, Stiffness, and Muscle Power Deficits: Midportion Achilles Tendinopathy Revision 2018: Clinical Practice Guidelines Linked to the International Classification of Functioning, Disability and Health From the Orthopaedic Section of the American Physical Therapy Association." Journal of Orthopaedic & Sports Physical Therapy 48(5): A1-A38.
De Vos, R. J., et al. "The additional value of a night splint to eccentric exercises in chronic midportion Achilles tendinopathy: a randomised controlled trial." British Journal of Sports Medicine 41.7 (2007): e5-e5.
De Jonge, Suzan, et al. "One-year follow-up of a randomised controlled trial on added splinting to eccentric exercises in chronic midportion Achilles tendinopathy." British Journal of Sports Medicine 44.9 (2010): 673-677.