Blog 2: The Overuse Injuries Playbook
Part 2: Achilles Tendinopathy: Why Your Achilles Hurts and How to Fix It Before It Gets Worse
Welcome to Part 2 of The Overuse Injury Playbook, a 12-part series covering the most common overuse injuries in endurance athletes. In Part 1, we covered plantar fasciitis and why your heel hurts. Now we're moving up the kinetic chain to tackle one of the most stubborn injuries runners face: Achilles tendinopathy.
If you're a runner, cyclist, or triathlete, you've probably felt that nagging ache in the back of your ankle at some point. The stiffness when you first start moving in the morning. The pain that shows up a few kilometers into a run and either improves or gets worse as you keep going. The tenderness when you press on the thick cord of tissue just above your heel.
This is Achilles tendinopathy. And if you ignore it, it can turn into one of the most stubborn overuse injuries you'll ever deal with.
What Achilles Tendinopathy Actually Is
Achilles tendinopathy is a breakdown of the Achilles tendon, the thick band of tissue that connects your calf muscles to your heel bone. The tendon is responsible for transmitting the force generated by your calf muscles to your foot, which is what allows you to push off the ground when you run, jump, or climb.
When the Achilles tendon is overloaded, it doesn't heal properly. The tissue becomes disorganized, weak, and painful. This is not just inflammation. It's a degenerative process where the tendon structure itself breaks down.
There are two types of Achilles tendinopathy:
Insertional Achilles tendinopathy affects the lower part of the tendon where it attaches to the heel bone. The pain is usually right at the back of the heel, and it's often worse when you first start moving or after long periods of rest.
Mid-portion Achilles tendinopathy affects the middle section of the tendon, about 2 to 6 centimeters above the heel. The pain is usually in the thick part of the tendon, and it often improves once you warm up but comes back after long runs or the next morning.
Both types are overuse injuries. They don't show up because of one bad step or one hard workout. They show up because of repetitive stress over time without adequate recovery.
Why Overuse Causes Achilles Tendinopathy
Achilles tendinopathy develops when the load placed on the tendon exceeds its capacity to recover. Here's what that looks like in endurance athletes:
Sudden increases in training volume or intensity. You ramp up your weekly mileage too quickly. You add speed work or hill repeats without building up to it. You jump into a new training block without giving your body time to adapt. The Achilles tendon can't handle the sudden increase in load, and it breaks down.
Tight or weak calves. If your calf muscles are tight, they pull harder on the Achilles tendon with every step. If they're weak, the tendon has to absorb more force than it should. Either way, the tendon is overloaded.
Poor running mechanics. Overstriding, excessive heel striking, or running with a forward lean all increase the load on the Achilles tendon. These patterns are often compensations for weak hips, poor core stability, or tight ankles.
Inadequate recovery. Running hard every day without rest. Not addressing tightness or fatigue. Ignoring the early warning signs of discomfort. Achilles tendinopathy is an overuse injury, which means it develops when your body doesn't have enough time to recover between training sessions.
Footwear issues. Worn-out shoes that no longer provide proper support. Switching to minimalist or zero-drop shoes without a gradual transition. Shoes with a heel-toe drop that doesn't match your foot mechanics. All of these can increase the stress on the Achilles tendon.
Early Warning Signs
Achilles tendinopathy doesn't show up overnight. It builds gradually. The first sign is usually a mild ache or stiffness in the back of your ankle that shows up in the morning or after sitting for a while. It improves once you start moving, so most runners ignore it.
If you catch it at this stage and address it, you can usually resolve it quickly. If you ignore it, the pain gets worse. It starts showing up during runs. It lingers after runs. Eventually, it shows up even when you're not running. At that point, it takes longer to resolve, and you're at higher risk for a partial or full tendon rupture.
The key is recognizing the early signs and addressing them before they turn into a bigger problem.
What Actually Fixes Achilles Tendinopathy
Achilles tendinopathy is fixable, but it requires addressing the root cause, not just the symptom. Here's what actually works:
Eccentric strengthening. This is the gold standard for treating Achilles tendinopathy. Eccentric exercises (where you slowly lower your heel below the level of your toes while standing on one leg) help rebuild the tendon structure and improve its capacity to handle load. This needs to be done consistently, not just once or twice.
Load management. If you're in the middle of a flare-up, continuing to run through the pain will only make it worse. You don't have to stop running entirely, but you do need to reduce the volume and intensity until the pain settles. Cross-training (cycling, swimming, strength work) can help you maintain fitness without aggravating the Achilles.
Soft tissue therapy. Targeted manual therapy to the calf muscles and surrounding tissues helps reduce tension and improve blood flow to the tendon. This is not the same as just foam rolling. It's about releasing the specific restrictions that are contributing to the overload.
Joint mobilizations. Gentle adjustments to the ankle and foot restore proper alignment and improve function. When your ankle is moving properly, the Achilles tendon doesn't have to compensate.
Gait analysis. If your running mechanics are contributing to the problem, those patterns need to be identified and corrected. A gait analysis can help pinpoint whether you're overstriding, heel striking excessively, or loading your foot in a way that's creating excessive stress on the Achilles.
Calf stretching and strengthening. Tight calves pull harder on the Achilles tendon. Weak calves force the tendon to absorb more load. Both need to be addressed. Regular calf stretches (both straight-leg and bent-knee) and progressive calf strengthening exercises help restore balance and reduce the strain on the tendon.
Footwear assessment. Make sure your shoes are providing adequate support and cushioning. Replace worn-out shoes. If you're transitioning to a new shoe type, do it gradually.
What to Watch For
If you're noticing pain or stiffness in the back of your ankle that's worse in the morning, pain that improves with movement but comes back after long runs, or tenderness when you press on the Achilles tendon, don't wait. Address it now.
Achilles tendinopathy can become chronic if it's not treated early. The longer you ignore it, the longer it takes to resolve. And the more likely you are to develop a partial tear or full rupture, which can sideline you for months.
When to Get Assessed
If you've been dealing with Achilles pain for more than a week or two, if the pain is getting worse instead of better, or if it's starting to affect your training, it's time to get assessed. Achilles tendinopathy is not something you have to just live with. It's fixable when you address the root cause.
Up Next:
In Part 3, we'll tackle shin splints: why your shins hurt, what causes them, and how to fix them before they turn into a stress fracture.
Dealing with Achilles pain or wondering if the ankle pain you're noticing needs clinical attention? Book a free 15-minute phone consultation or a full assessment at Endurance Therapeutics with me, Dr. Keirstyn, or any of the team! We help runners address the root cause, not just the symptom.
📍 Endurance Therapeutics | Oakville, Ontario
📞 905-288-7161