If you’re a runner dealing with pain in the back of your heel or along the inside of your ankle, a tendon may be the source of the problem. In many cases, the tendon has been asked to handle more load than it can currently tolerate. This does not necessarily mean something is structurally broken.
Runners are especially prone to two tendon issues: Achilles tendinopathy and tibialis posterior tendinopathy. Knowing the difference between these conditions can help you understand your symptoms and determine the right approach to recovery.
Achilles Tendinopathy in Runners
The Achilles is the strongest and thickest tendon in the body. It also takes a significant amount of stress during running, with forces reaching four to eight times your body weight. Achilles tendinopathy usually causes pain in the tendon itself. The pain may increase with touch, stretching, or activities that load the tendon.
Many runners also experience stiffness, especially first thing in the morning. Some people may notice that the tendon becomes thicker over time. Achilles tendinopathy is classified as either mid-portion or insertional, depending on where the pain occurs. Mid-portion Achilles tendinopathy is more common.
Many runners worry that Achilles pain means their tendon is going to rupture. However, tendinopathy does not mean that a rupture is about to happen. Achilles ruptures usually happen suddenly during forceful movements, such as sprinting or cutting, rather than from a gradual increase in tendon pain.
Tibialis Posterior Tendinopathy in Runners
The tibialis posterior tendon runs behind the inner ankle bone and helps support the arch of your foot. It plays an important role during standing, walking, and running.
This condition often develops after a sudden increase in running mileage. The tendon may not be prepared for the extra demand, leading to an overload. Pain is usually felt along the inside of the ankle or foot.
You may also notice that your foot looks more pronated or flattened. Another common sign is difficulty performing a single-leg heel raise. In more advanced cases, you may not be able to perform one at all.
Having naturally flat feet does not mean you will develop tibialis posterior tendinopathy. However, a sudden increase in training combined with your existing foot structure may place more stress on the tendon.
Why Runners Need to Manage Load, Not Just Rest
Both conditions have something important in common: the tendon is being asked to handle more load than it can currently tolerate. This is why simply resting until the pain goes away may not be enough. Going straight back to your previous mileage can cause the same problem to return.
Instead, recovery usually involves gradually adjusting your training. This can include changing your running speed, distance, or frequency. Targeted strengthening exercises, such as calf raises and heel-raise progressions, can also help rebuild the tendon’s ability to handle load.
The goal is not to avoid loading the tendon completely. The goal is to gradually expose it to an appropriate level of stress. Over time, this helps the tendon become stronger and better prepared for running.
What This Means for Your Training Plan
If you’re currently dealing with one of these conditions, complete rest may not address the underlying problem. You may feel better while resting, but the tendon still needs to rebuild its capacity before you return to your previous mileage.
A better approach is often to maintain some level of activity within a tolerable range. From there, you can gradually increase your strength and running volume. The right progression will depend on your symptoms, training history, and how your tendon responds to increased load.
Recovery usually takes weeks to months rather than days. Trying to rush back to your previous mileage can set you back. Consistency with your rehab and training progression is more important than getting back to running as quickly as possible.
When to Get a Proper Evaluation
If you’re not sure which tendon is causing your symptoms, consider getting a proper evaluation. The same is true if your pain isn’t improving after making reasonable changes to your training.
An evaluation can also be helpful if you have other issues, such as chronic ankle instability from a previous sprain. Identifying the factors contributing to your symptoms allows you to build a rehab plan around your specific needs.
The goal isn’t just to get rid of your pain. It’s to rebuild the strength and capacity you need to return to running and handle your normal training load.
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Dr. Jonny Blue is a Doctor of Physical Therapy and founder of Land and Sea Physical Therapy in Oceanside, CA. He specializes in orthopedic PT, root cause methodology, and helping active adults in North County San Diego get back to the activities they love without surgery or pain medication.