The Achilles Tendon Explained

In brief: The Achilles tendon is the thick, strong cord at the back of the ankle that connects the calf muscles to the heel bone. It transfers the power of the calf to the foot, making it essential for pushing off, jumping and running. It is the largest tendon in the body.

What is the Achilles tendon?

The Achilles tendon is the large, rope-like band at the back of the lower leg that joins the calf muscles to the heel bone. It is the strongest and thickest tendon in the body and is easy to feel as the firm cord just above the heel.

Why it matters

Every time you push off the ground, the calf muscles pull through the Achilles tendon to lift the heel and drive you forward. This makes it one of the most important structures for running, sprinting and jumping, and it handles forces many times your body weight.

How it works

The tendon stores elastic energy as it stretches when the foot loads, then returns that energy as it recoils during push-off. This spring-like action makes running more efficient by reducing how much work the muscles have to do.

What to look for

Gradual training, calf strength and flexibility, and shoes with an appropriate heel height all help the Achilles cope with running. Heel-to-toe drop in a shoe changes how much the tendon is stretched, which is why some runners feel it more in flatter shoes.

The Achilles tendon and your running kit at OD's

Heel drop and cushioning affect how the Achilles loads. The team in St Helens can explain how different shoes feel through the heel and calf, and we offer next-day delivery and free click and collect.