Managing Achilles Tendon Pain After Running

Achilles tendon pain after running is a common complaint among active people, and for some, it becomes persistent. The Achilles tendon is the largest tendon in the body and one of the most frequently injured. Several conditions cause pain in the Achilles tendon after running, and because each is treated differently, an accurate diagnosis matters. This guide covers every cause and how we tell them apart.

For the full treatment programme once you have a diagnosis, see our Achilles tendonitis in runners guide and the clinical overview of Achilles tendinopathy.

Common cause: Achilles tendonitis

Achilles tendonitis (tendinopathy) is the most common cause. Excess load over a short period swells the tendon and breaks down its collagen, causing pain during and after running. The pain typically sits in the middle of the tendon or low down near the heel, warms up with activity, and worsens afterwards.

Less common causes of Achilles tendon pain after running

Achilles paratenonitis

The paratenon — the sheath around the tendon — can swell rather than the tendon. The giveaway is a creaking or “crepitus” sensation with ankle movement, and it needs a different treatment from tendonitis.

Achilles tear or partial tear

Sometimes the collagen fibres tear, causing sudden, sharp pain — people often describe feeling “kicked” in the Achilles tendon and diagnosing an Achilles tendon tear matters because the treatment differs from that for tendonitis.

Plantaris-related Achilles pain

The plantaris tendon runs alongside the inner Achilles tendon and, in some people, rubs against it — causing pinpoint pain along the inner tendon that may require a modified programme and sometimes an injection or surgery.

Os trigonum and posterior ankle impingement

Os trigonum is an extra bone at the back of the ankle. After an injury such as an ankle sprain, swelling around the ankle can cause pain that is often mistaken for Achilles tendon pain.

Subtalar joint arthritis

Arthritis of the subtalar joint, just above the heel, can refer pain to the back of the ankle near the lower Achilles tendon.

Kager’s fat pad oedema

Swelling of Kager’s fat pad, between the Achilles and heel bone, causes discomfort at the back of the ankle and often co-occurs with Achilles tendonitis.

How do we diagnose Achilles tendon pain?

Generally, Achilles tendonitis pain is “warm-up” pain — eases during activity, worse afterwards — sits at the tendon, and worsens with calf raises, jumping, or hopping. We also assess calf strength, since calf weakness drives the problem.

Imaging confirms the diagnosis and excludes other causes. Ultrasound is cheap and quick, showing collagen thickening. MRI adds detail and shows non-tendon causes such as os trigonum or subtalar arthritis—notably, a normal tendon scan points towards a non-tendon cause.