Updated: Jun 6
Not everyone who has Achilles tendonitis has to stop running, but this doesn’t mean that it’s OK to keep on running regardless of pain or other symptoms. This article explains how you can decide whether running with Achilles pain is OK and how to adapt your running so that your Achilles can heal and recover. But first, it’s important to understand what happens in your tendon when it is injured and how to interpret your symptoms. 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:
Quick recap - What is Achilles tendonitis/tendinopathy?
Achilles tendonitis is an overuse injury. It develops when you overwork your Achilles tendon either by increasing the intensity or volume of your running too quickly or if you don’t allow it enough recovery time between hard training sessions.
The Achilles tendon is mostly made up of collagen fibres that are packed tightly in parallel. It is this parallel arrangement that makes the tendon so strong.
Your Achilles tendon (and muscles) sustain microdamage when you train. This is natural, and if you allow your body enough recovery time, it repairs the damage and your tendon grows stronger than before and is able to handle even more load.
If you don’t allow sufficient recovery time, the microdamage accumulates, and eventually the collagen fibres in a portion of the tendon lose their parallel arrangement. That part of the tendon loses some of its strength and can no longer cope with the normal forces and loads of running. This article discusses some of the warning signs that your calves / Achilles tendons are not getting enough recovery time.
How to interpret your Achilles tendonitis symptoms
The most common symptoms that people with Achilles tendonitis or tendinopathy complain of are pain and stiffness. The pain and stiffness are usually worst first thing in the morning and improve as you start moving about.
Not everyone will feel pain and not everyone will feel stiffness. For some the stiffness outlasts the pain and for others it’s the other way around.
Pain is not a good measure of whether you can run
It’s important to understand that Achilles tendonitis usually does not affect the whole tendon – just a portion. And just because you have a lot of pain does not mean that your tendon is very weak.
Pain is the alarm system of the body. Some people have the ability to switch the alarm system off (most endurance athletes can ignore pain). Other times, the alarm system can get super sensitised and cause pain that is disproportionately high compared to the actual damage.
A recent study by Hanlon et al. confirmed what we've also observed in practice. They showed that some patients can have really high levels of pain while their scans indicate only minor structural damage. In these cases, their alarm systems are a bit too sensitive. This can happen when you ignore your pain and just continue to train through it – the alarm system starts shouting louder and louder to get your attention. But other factors like your thoughts, beliefs, and feelings can also affect it.
Other people may have nearly no pain but quite a lot of structural damage.
So, it is possible to have quite a strong tendon but a lot of pain or have a tendon that’s lost a lot of its strength but feel nearly no pain.
Therefore, we can’t just rely on pain to know what volume or intensity of running is safe for you. We have to look at other factors too.
What does the level of tendon stiffness signify?
We don’t really know. I’m not aware of any studies that have investigated whether there is a correlation between the amount of tendon stiffness a patient reports and the level of tissue damage seen on their scans.
What I know from experience is that once my patients start reporting improvements in the intensity or duration of stiffness they experience first thing in the morning, we usually start seeing good results with their rehab. I’ve learnt to see it as an indication that their rehab and running are pitched at the correct level and their tendon is recovering.
Why ignoring Achilles pain and stiffness is not a good idea
It might mean that you’re making your injury worse
If you continue to overload your tendon and don’t do anything to restore the lost strength, it can cause your tendon to rupture. This is not very common, as most people seek help before this happens. It is very easy to avoid by applying the concept of load management that I explain lower down.
It can cause your body’s alarm system to become super sensitive
As I explained earlier, just because your Achilles hurts more does not always mean that you’ve damaged it further. It might just mean that you’ve set your alarm system off. But if you continue to irritate the alarm system, your Achilles pain can eventually become so bad that it stops you from doing anything, which is also not useful.
Adapting your running to allow tendon healing
An Achilles tendon that is weakened by injury may no longer be able to cope with your normal running load, but it might be able to cope with a reduced running load.
So, if you can adapt your training to a level within the current capacity of your tendon, you can continue to train without aggravating your injury. In fact, by continuing to train within this “safe” zone, you’ll also maintain your tendon’s strength. This approach is called “relative rest”, and research has found that this is better than complete rest for an injured tendon.
Some of the adaptations that we find can work for running safely with Achilles tendonitis:
Avoid fast running
Avoid hill sessions or hilly runs
Avoid running on very soft surfaces, like sandy beaches
Keep your runs short
Do fewer running sessions per week.
Reducing the running intensity and volume will not work for everyone. Sometimes it is necessary to take a break from running and switch to cycling or swimming to maintain fitness while you restore your tendon’s strength through targeted exercises.
Keep in mind that you should not just adapt your running; you should also be doing specific rehab exercises to regain the strength in your Achilles tendon and rest of your body.
Be guided by changes in your symptoms
When you have Achilles tendonitis, you will have a certain “normal” level of pain and stiffness that varies throughout the day. This is seen as your base level of symptoms.
When we want to know whether an activity was beneficial or perhaps too intense, we look for changes in the base level both while your doing the activity and in the 24 hours after you have completed it.
It is quite normal to feel that your tendon pain improves while you run, only for it to become really painful and stiff in the 24 hours after the run. Tendons are sneaky this way – they seldom let you know in the moment that you’re overdoing things.
This is why it is important not only to focus on how much pain or stiffness you feel while you’re running, but also to monitor the 24-hour symptom response.
It is normal to experience a slight increase in pain and/or stiffness during an activity or somewhat later, but it should not cause a significant increase and it should settle back down quickly. A general rule that seems to work well for our patients is that a run is usually pitched at the correct level if:
Your pain increases only slightly (no more than 3/10) while you’re doing the run, and
your discomfort settles back down within an hour or two after the run, and
the amount of pain or stiffness you normally feel does not increase in the 24 hours after.
It is usually a sign that your run was too long or too intense if:
You felt more than a slight discomfort (more than 3/10) during the run, or
you experienced a significant increase in your normal level of pain or stiffness, and it lasted for more than 24 hours after the run.
Help, there’s a very important race that I have to run despite my Achilles pain!
I’ve had several messages from runners desperate to run the London marathon or similar races for charity. It is usually a very important event for them, as they are often doing it in memory of a loved one who has passed away.
There are some things that you can do to help you run and finish a race even if you have Achilles pain, but you have to understand that this will not protect your Achilles tendon or stop the injury from worsening. Things that might help you get through the race include:
In training, significantly reduce your running, e.g. switch to run-walk sessions, or stop running altogether and cross train instead. Try to maintain fitness but at the same time get your Achilles to calm down. You’re better off doing shorter and slower pain-free runs than trying to continue doing long runs and aggravating your injury further. If you want help figuring out what the optimal mix of running and cross training is for you, this is something that our team can help you with via video call.
Adjust your goals for race day. You will not be able to run it as fast as you like, because fast running loads the Achilles tendon significantly more. You are much more likely to finish the race if you go slow and walk large parts of it.
It might help if you place small heel lifts in your shoes to take some of the strain off your Achilles tendons. This can be a gamble if you’ve not tested it out before race day, as they may not work for you and cause discomfort in other areas. It is best to test them during training and only use them in the race if it feels 100% comfortable.
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
Cook J, Docking S. “Rehabilitation will increase the ‘capacity’ of your …insert musculoskeletal tissue here….” Defining ‘tissue capacity’: a core concept for clinicians. British Journal of Sports Medicine 2015;49(23):1484-85. doi: 10.1136/bjsports-2015-094849
Hanlon, Shawn L., Ryan T. Pohlig, and Karin Grävare Silbernagel. "Beyond the diagnosis: Using patient characteristics and domains of tendon health to identify latent subgroups of Achilles tendinopathy." Journal of Orthopaedic & Sports Physical Therapy 51.9 (2021): 440-448.