Peroneal Tendonitis in Runners: A Clear and Simple Explanation

There are fewer instances of peroneal tendonitis in runners than there are of other foot injuries like plantar fasciitis or achilles tendonitis

And because of this fact, most people, including runners, have never even heard of it. What is it? What are its causes? 

How can one prevent it? Or how can one treat it if one suffers from it? 

We’re going to answer all those questions here, as clearly and as succinctly as possible.

What is Peroneal Tendonitis? 

The first thing you should know is that a tendon is a band of fibrous tissue that attaches your muscle to your bone.

The second thing is that each of your legs contains what is called the peroneal tendons – “peroneal” means related to or situated in the outer side of the calf. Peroneal tendons run down each calf side by side and attach to the foot in two different spots.

There are two peroneal tendons in each leg. One of these attaches to the base of the pinky toe (called the 5th metatarsal) on the outside of the foot; the other to the inside of the arch from underneath the foot. When these tendons are overloaded and strained, they begin to rub on bone, which causes inflammation. This in turn causes swelling in the tendons.

And that, in simple terms, is what peroneal tendonitis is – an inflammation of the peroneal tendons.

If left untreated and continue to be overworked, the peroneal tendons will thicken in order to adapt to and be able to handle the excessive workload. This will make them vulnerable to other, more serious injuries, such as tearing.

What does peroneal tendonitis feel like?

Now that you have a visual sense of where the peroneal tendons actually are, you shouldn’t have a problem assessing and differentiating peroneal tendonitis from other kinds of running ailments. If you have peroneal tendonitis, you should be feeling an aching or sharp sensation along the tendons or on the outer part of your foot, around the ankle. Running with peroneal tendonitis will be painful, but standing still or applying gentle pressure to the area shouldn’t yield too much pain.

If you feel an excessive amount of pain even when resting or when doing gentle stretches, you might have a fracture or something else entirely.

Causes of Peroneal Tendonitis in Runners 

There are several causes of peroneal tendonitis. As we mentioned above, the main cause is overworking. Peroneal tendonitis in runners in particular is caused by faster running speeds. This is because the faster someone is running, the higher the level of activity in the muscles surrounding the ankle; and the higher that activity, the more strain the peroneal tendons have to contend with just to keep the foot stabilized.

Participating in high-intensity interval training, like Tabata, also increases your chance of getting peroneal tendonitis.

Other factors that contribute are:

  • Increasing weight-bearing activity (walking, running, or jumping) too quickly or suddenly
  • Improper running form
  • Inadequate or inappropriate running shoes

Previous research also indicates that higher foot arches are also a risk factor for peroneal tendonitis in runners. The higher your arch, the higher your risk.


In order to prevent peroneal tendonitis, you simply have to address and counteract the causes above.

  • If you wish to increase weight-bearing activity, do so gradually; avoid running faster too suddenly
  • Perfect your running form – click here for our article on how to do just that
  • Wear adequate and appropriate running shoes
  • You should also make sure to stretch properly before running

Treatment of Peroneal Tendonitis in Runners 

If prevention is no longer an option, treating it is. The first thing you’ll need to do is to determine whether or not the pain around your ankle is actually tendonitis or whether the pain stems from something else. This can only be done by getting a professional diagnosis from a doctor. An X-Ray or an MRI scan may also be utilized to rule out any abnormalities or fractures.

The mainline of treatment for peroneal tendonitis in runners is, almost common sensically, rest. Remember, peroneal tendonitis is an injury resulting from overwork and overuse; it follows that in order to heal, the tendons would require a little vacation.

In order to do this, you may have to completely make the foot immobile by using support to walk. Medication like ibuprofen can also help reduce swelling and pain, as can physical therapy. In rare cases, bracing might be required until the foot is healed; in even rarer cases, the doctor might recommend cortisol injections to reduce swelling and inflammation. But this last comes with a risk of rupture, which is why it’s not recommended in normal circumstances.

If all of the above nonsurgical options fail to deliver results, surgery might be necessary.

Final thoughts

If taken care of and treated in a timely fashion, peroneal tendonitis is a fairly harmless injury. The most important thing to remember is that you should take your time and ease back into running once you’re healed. And when you’re healing, it would behoove you to refrain from working your peroneal tendons at all – in fact, you should strive to keep weight off of the affected ankle.

If left untreated, the relatively harmless peroneal tendonitis can lead to a tear, which can increase the risk of a sprain or even nerve damage.

So remember to just play it safe and you’ll be back at it in no time.

Good luck!


  1. Kyle Kranz
  2. Run Research Junkie
  3. Runners Connect
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