Achilles Tendinopathy

By Runsense · Reviewed by Raphael Crawford-Marks, Founder · Last reviewed June 9, 2026

Achilles tendinopathy — pain and stiffness in the Achilles tendon at the back of the ankle — is one of the most common overuse injuries in runners. The good news is that it usually responds well to patient, progressive loading; the catch is that tendons adapt slowly, so rushing it tends to drag things out. This is general education, not a diagnosis or treatment plan: for that, see a sports-medicine professional.

What it is

It's a load-related problem of the Achilles tendon — the thick cord connecting your calf muscles to your heel. The classic signs are pain and stiffness that are worst with the first steps in the morning (or after sitting), ease as you warm up, and often return after a run1. Most cases are *mid-portion* (a tender, sometimes thickened spot a few centimeters above the heel); some are *insertional* (right where the tendon meets the heel bone). It reflects a tendon struggling to keep up with load, not an imminent rupture.

Why runners get it

Like most running injuries, it typically follows a load spike — a jump in mileage, and especially more hills or faster running, both of which load the Achilles hard — combined with too little recovery. Reduced ankle mobility or calf weakness can contribute. The tendon gets loaded faster than it can adapt, and the result is pain and stiffness.

How it's generally managed

The best-supported cornerstone is *progressive loading* — calf- and tendon-strengthening exercise — alongside managing how much you run. Clinical guidelines specifically recommend a structured loading program (eccentric and heavy-slow calf work) for mid-portion Achilles tendinopathy1. In broad terms:

When to see a professional

See a sports-medicine professional if Achilles pain persists beyond a couple of weeks, isn't improving, or keeps returning when you build up — they can confirm the diagnosis and build the right loading program. Seek prompt care for a sudden, sharp "pop" or snap at the back of the ankle with a loss of push-off power — that can signal a tendon rupture and needs urgent assessment.

Safety

This article is general education, not medical advice, diagnosis, or a treatment plan. Pain at the back of the ankle has more than one cause; a sports-medicine professional should diagnose and guide treatment. A sudden sharp pop or snap with loss of push-off power warrants urgent evaluation (possible Achilles rupture).

Sources

  1. Martin RL, Chimenti R, Cuddeford T, Houck J, Matheson JW, McDonough CM, Paulseth S, Wukich DK, Carcia CR. Achilles Pain, Stiffness, and Muscle Power Deficits: Midportion Achilles Tendinopathy Revision 2018. Clinical Practice Guidelines. Journal of Orthopaedic & Sports Physical Therapy 48(5):A1-A38 (2018). (JOSPT clinical practice guideline on midportion Achilles tendinopathy)

One running guide a week.

Calm, useful, no spam. Plain-English coaching from the Runsense team, once a week.