Achilles Tendinopathy in Runners: Causes, Symptoms, and Treatment

If you run long enough, there is a good chance your Achilles tendon will eventually remind you that it exists. Achilles tendinopathy is one of the most common running injuries, affecting roughly 6-10% of runners each year,  and is something that Miles Ahead Physical Therapy and Performance has helped many runners in Boston overcome.

Sometimes it starts as a little stiffness when you get out of bed in the morning. Often it’s worse early in a run and then improves once you get moving. Other times, achilles pain pops up later in runs. In more irritable cases, achilles pain in runners gets bad enough that running becomes difficult or impossible.

It is also one of the most misunderstood.

Many runners have been led to believe that the answer is some combination of rest, stretching, and eccentric heel drops. While those things can sometimes help to a degree, Achilles tendinopathy is complex and the way physical therapy for runners can best treat this injury has evolved. Understanding what is happening inside the tendon helps explain why certain treatments work and why others often fall short.

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What Is Achilles Tendinopathy?

The Achilles tendon connects the calf muscles to the heel bone. The gastrocnemius and soleus muscles merge to form the Achilles tendon, which attaches to the back of the heel bone, the calcaneus.

Every step you take while running places a large amount of force through the achilles tendon. During running, the Achilles tendon can experience forces greater than six to eight times body weight.

The Achilles tendon acts like a spring. It stores energy when your foot lands and releases that energy when you push off the ground.

When the Achilles tendon is exposed to more load than it can currently tolerate, it can become painful. This condition is called Achilles tendinopathy.

Despite the name, the condition is usually not driven primarily by inflammation. Instead it reflects changes in the tendon structure that occur when the tissue is exposed to repeated overload.

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What Happens at the Tissue Level

Healthy tendon tissue is made primarily of collagen, arranged in highly organized parallel fibers. This organized structure allows the tendon to tolerate very high forces while remaining stiff and efficient.

In Achilles tendinopathy, several structural changes occur within the tendon.

1. Collagen fibers become less organized, and weaker.

2. New blood vessels form within the tendon. These vessels are often accompanied by small nerve fibers that may contribute to pain.

3. Fluid is often drawn into the tendon, causing thickening of the tendon.

Importantly, these changes do not necessarily mean the tendon is permanently damaged. 

With the right treatment, tendons can remodel and improve their function over time.

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Mid Portion vs Insertional Achilles Tendinopathy

Not all Achilles injuries occur in the same location.

Two main forms affect runners.

Mid portion Achilles tendinopathy

This occurs roughly two to six centimeters above the heel bone and is the most common type of Achilles tendinopathy seen in runners.

This region of the Achilles tendon experiences high repetitive loading and has relatively lower blood supply compared with other areas.

Typical symptoms include:

    •    Pain in the middle portion of the tendon

    •    Morning stiffness

    •    Pain during the first part of a run that may improve as you warm up

Mid portion Achilles tendinopathy often responds well to progressive loading programs that gradually increase the strength and capacity of the tendon.

Insertional Achilles Tendinopathy

Insertional Achilles tendinopathy occurs where the tendon attaches directly to the heel bone.

This form behaves slightly differently because the tendon can be compressed against the heel bone when the ankle moves into deeper ranges of motion.

Activities that increase this compression can aggravate symptoms, including:

    •    Hill running

    •    Uphill walking

    •    Deep calf stretching

Common symptoms include:

    •    Pain directly at the back of the heel

    •    Sensitivity when shoes press on the tendon

    •    Pain during uphill running or deep stretching

Rehabilitation often needs to modify early exercises, day to day activity, and footwear to reduce excessive compression at the insertion while the tendon becomes stronger.

Why Runners Develop Achilles Tendinopathy

In most cases, Achilles tendinopathy develops because training load exceeds the tendon’s ability to manage that stress.

Simply put, the Achilles tendon is being asked to do more work than it is prepared to handle.

Common contributing factors include:

Rapid increases in training load

Sudden mileage increases, new speed workouts, or hill training can significantly increase stress on the Achilles tendon.

Sudden changes in footwear

Switching to lower drop or minimalist shoes can increase the load placed on the Achilles. These changes are not necessarily harmful, but they require gradual adaptation.

Calf weakness

The calf muscles are critical for running, and have to deal with a lot of force. If they are not strong enough for the demands you are placing on them with your training, the Achilles tendon may become injured.

Returning to running after time off

After a break from running, the tendon loses some of its load tolerance. Jumping back into training at too high of an intensity level or volume can overload the tissue quickly.

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Treatment for Achilles Tendinopathy in Runners

The goal of treatment for Achilles tendinopathy in runners is not simply to calm down symptoms. The goal is to increase the tendon’s ability to tolerate load.

Progressive strength training

Calf strengthening exercises are the foundation of most rehabilitation programs.

Heavy resistance training that puts beneficial load through the Achilles tendon has been shown to improve pain and function in people with Achilles tendinopathy. 

These exercises are not simply eccentric heel drops. Loading the calf muscles and Achilles through a variety of movement types is most effective.

These exercises help stimulate tendon remodeling and increase the tissue’s load capacity.

Managing running load

Many runners can continue running with Achilles tendinopathy as long as symptoms remain within a manageable range. In fact, running is often a beneficial part of rehabilitating the tendon. Cutting back too much on running can be detrimental to overcoming Achilles tendinopathy. 

Temporary adjustments to mileage, hills, or intensity can allow the tendon to recover while still maintaining fitness and facilitating healing.

This is part of why working with a running specialist physical therapist who is also a running coach is so beneficial. Miles Ahead Physical Therapy and Performance offers exactly this for runners in Boston.

Increasing Strength and Durability Throughout the Lower Limb

Muscles throughout the lower limb all influence how force travels through the leg during running. Improving overall strength can reduce excess stress on the Achilles tendon.

Time and consistency

Tendon adaptation takes time. Many runners begin noticing improvement within several weeks, but full recovery often takes at least a few months depending on the severity of symptoms. More severe cases of Achilles tendinopathy can take 6-12 months to fully resolve.

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Common Questions Runners Ask About Achilles Tendinopathy

Can I keep running with Achilles tendinopathy?

In many cases, yes.

Most runners do not need to stop running completely. The key is managing training load so symptoms remain manageable. In fact, continuing to run is often an important part of the rehab process.

Pain during a run should generally stay mild and return to baseline by the next morning. If symptoms are progressively worsening, training load may need to be reduced temporarily.

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How long does Achilles tendinopathy take to heal?

Recovery timelines vary.

Many runners notice improvement within several weeks of treatment.

Full recovery and return to normal training often takes at least 3 months, with more severe cases often taking 6-12 months to heal. 

This is a long time. However, with the right guidance and treatment plan, runners dealing with achilles tendinopathy can often continue to train throughout this process.

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Is stretching helpful for Achilles tendinopathy?

Stretching may provide temporary relief for some runners, but it is usually not the primary driver of recovery.

For mid portion Achilles tendinopathy, gentle stretching may be tolerated.

For insertional Achilles tendinopathy, aggressive stretching into deep dorsiflexion may actually increase compression at the tendon insertion and worsen symptoms.

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What exercises help Achilles tendinopathy?

Rehabilitation programs typically include:

    •    Heel raises

    •    Seated calf raises

    •    Single leg control exercises

    •    Progressive heavy resistance exercises for the lower limb

As symptoms improve, programs may progress toward single leg loading and plyometric exercises that better prepare the tendon for running.

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When should I see a physical therapist?

If Achilles pain has been present for more than a couple of weeks or is limiting your ability to run, it can be helpful to get an evaluation.

A thorough assessment should examine training history, strength, running mechanics, and recent training changes to determine why the tendon became overloaded.

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Final Thoughts

Achilles tendinopathy can be frustrating for runners who want to stay consistent with training.

The good news is that most cases respond well to the right combination of load management and strengthening.

Instead of focusing only on rest, stretching, or passive treatments like massage or dry needling, the long term solution is to gradually improve the tendon’s ability to handle the demands of running. When the tendon’s capacity increases, symptoms often improve as well.

If you are dealing with Achilles pain and are not sure how to manage it, getting the right plan in place early makes a huge difference.

At Miles Ahead Physical Therapy and Performance, I work with Boston runners of all levels to overcome injury and get back to running stronger than ever. If you are a runner looking for running physical therapy in Boston and could use some help, you can learn more about working together or book an appointment here.

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