Understanding Achilles Tendinopathy: What Runners Need to Know
Kelsie Mazur, DPT
With the Chicago Marathon around the corner, I’ve been seeing a surge of runners coming into the clinic with one of the most common running-related injuries: Achilles tendinopathy. In fact, I currently have four patients dealing with it. Let’s break down what it is, why we use that term, and what runners should know. Buckle up, this is a long and informative blog, so feel free to bounce around using the labeled sections.
Why do we call it “Tendinopathy” and Not Tendinitis or Tendinosis?
For years, people referred to painful Achilles problems as tendinitis (inflammation of the tendon) or tendinosis (degeneration of the tendon). But here’s the thing, research shows that Achilles tendon pain isn’t always just inflammation or degeneration.
Instead, what we usually see is a combination of:
• Pain in the tendon with activity or after activity
• Reduced function, such as trouble pushing off, jumping, or running
• Symptoms that are closely tied to how the tendon is loaded, meaning how much stress you place on it during training
Because of this, the umbrella term Achilles tendinopathy is now preferred. It better reflects what’s actually happening: persistent pain and impaired function related to mechanical loading, not just inflammation or “wear and tear.”
Two Different Types: Mid-Portion vs. Insertional Achilles Tendinopathy
Not all Achilles pain is the same. Where the pain shows up helps guide treatment.
Mid-Portion Tendinopathy
Location: Pain and stiffness in the middle of the tendon, typically 2–6 cm above where it attaches to the heel bone.
Who gets it: Often distance runners, especially during marathon training when mileage spikes.
Key feature: Pain is usually worse when running, jumping, or doing explosive activities.
Insertional Tendinopathy
Location: Pain right at the bottom of the tendon where it attaches to the heel bone.
Who gets it: Runners, but also athletes who do more hill running, sprinting, or activities with repetitive uphill stress.
Key feature: Pain is aggravated by compressive loads, such as stretching the calf or running uphill.
Why Did You Get Achilles Tendinopathy?
No matter where your symptoms show up, the natural question is: why did this happen in the first place?
The simple explanation is that Achilles tendinopathy develops when the stress placed on your tendon through walking, running, or sports goes beyond your body’s ability to handle and recover from it. I explain this to my patients as when the “load outweighs your capacity,” that’s when problems can arise. But of course, this plays out differently person to person.
For active individuals, such as runners: It’s often a case of “too much, too soon.” For example, if you’re comfortable running half marathons but then quickly ramp up your mileage to prepare for a full marathon, that sudden jump in training may outpace what your tendon is ready for.
For less active individuals: The opposite can happen. A gradual drop in daily activity and overall fitness lowers your capacity, making the tendon more vulnerable to everyday stresses that once felt easy.
That’s why the goal of rehab isn’t just about reducing pain. It’s about restoring balance so your capacity matches, or ideally exceeds, the loads you put on your tendon day to day. And don’t forget, factors like sleep, stress, and nutrition play a huge role in how well your tendon adapts.
The Role of Pain in Rehab
Another fundamental component of rehab for Achilles Tendinopathy is understanding and monitoring pain.
Do you have to avoid pain during exercise, or is it safe to push into a little pain? Many people are concerned that exercising into pain means they’re damaging their tendon or making things worse. That isn’t necessarily true. (I wrote a blog about pain in rehab, you can read it here)
You’re not only going to monitor symptoms during exercise, but also immediately after and the following day. Ask yourself these three questions:
Is my pain tolerable during exercise? If it’s helpful for you, rate your pain on a scale from 0–10 and decide on the highest acceptable number. Some physical therapists recommend staying at a 3/10 or less, while others are comfortable with 5/10 or less. The exact number is less important than choosing a threshold that feels safe and sustainable for you.
Is my pain better, worse, or the same after exercise? Achilles tendinopathy may show what’s called a “warm-up phenomenon,” where symptoms actually improve once you get moving. It’s possible that you’ll feel better after activity than when you started.
Is my pain better, worse, or the same the next day? This is the most important question. If you feel fine during and immediately after exercise, but symptoms flare up significantly the next day, that’s a sign that the current dosage is too much and needs to be scaled back.
You can assess next-day symptoms through your usual daily activities, like walking or by using a specific test such as a heel raise.
My most FAQ: Do You Have to Stop Running?
Not necessarily. You can often keep running as part of your rehab process, but you’ll likely need to make some changes. That might mean cutting back on total weekly mileage, reducing the number of runs per week, or adjusting intensity (speed/terrain). You can make up the difference with strength exercises or other forms of cross-training that load the tendon in a safer, more controlled way. If you continue to run but find yourself consistently overdoing it and falling into a DOOM and GLOOM cycle of pain, it may be worth considering a short break. You don’t want to turn a six-month recovery process into a two-year process by being impatient early on.
For runners and non-runners alike, walking is also an important part of rehab. Every step loads the Achilles tendon, and that load can be used productively. Track your steps, adjust as needed, and aim to gradually increase over time. If you’re training for the Chicago Marathon and notice morning stiffness in your Achilles, pain when pushing off, or soreness that lingers after runs, don’t ignore it. Early management makes all the difference.
The Importance of Seeing a Skilled Physical Therapist
While it’s tempting to just “rest and wait” or search online for quick fixes, Achilles tendinopathy rarely resolves on its own without the right plan. This condition can be stubborn. If it lingers, it can limit not only your running but also simple daily activities like walking, climbing stairs, or even standing for long periods.
That’s why it’s important to see a skilled Doctor of Physical Therapy early on.
A DPT can:
• Identify whether your pain is mid-portion or insertional, which drastically changes the approach.
• Design a progressive loading program that matches your unique capacity and training goals.
• Help you avoid common pitfalls, like stretching when you shouldn’t or pushing too hard, too soon.
• Consider the bigger picture: your sleep, stress, footwear, strength, and running mechanics to ensure your tendon gets the best chance to adapt and recover.
The truth is, the longer you wait, the more challenging recovery can become. What could have been a three-to-six-month rehab process might turn into a year or longer if the tendon keeps getting overloaded without the right adjustments. Seeing a physical therapist isn’t just about treating pain, it’s about regaining confidence, building resilience, and getting back to the activities you love without the fear of setbacks! Nip this in the bud now, and you’ll thank yourself later when you’re running stronger and staying injury-free.
Let’s chat! Book an assessment and let’s get you back to feeling good in your body.
No referrals, no waiting, just answers. Did you know that we offer free 1-on-1 injury screens? Wattage Physical Therapy will take an in depth look at your ergonomics, posture, muscle tone, muscle weaknesses, and movement patterns to create a plan for YOU. If this article intrigues you, you can directly email me, Kelsie at Kelsie@wattagept.com. I would be happy to help you start the process of living a life free from pain.