03/08/2026
Here’s a simple diagram I use with clients to explain why calf and ankle capacity is so important.
The numbers aren’t exact, but the principle absolutely is.
Every time your foot strikes the ground, the ground pushes back with an equal and opposite force - Newton’s Third Law. This is known as Ground Reaction Force (GRF).
Your body doesn’t simply absorb this force, your muscles and tendons actively manage it.
During running, the gastrocnemius, soleus and Achilles tendon are responsible for producing and transferring a significant proportion of this force, acting like a spring to store and release energy with every stride.
But what happens if they can’t cope?
The load doesn’t disappear; it gets redistributed. The knee, hamstrings / quads, lower back or even another muscle group is forced to compensate, often increasing the risk of pain or injury elsewhere.
That knee pain that seemed to come “out of nowhere” might not actually be a knee problem. It could be a calf complex that lacks the strength, endurance or capacity to meet the demands placed upon it.
That’s why building calf capacity isn’t just about stronger calves; it’s about creating a more resilient lower limb and improving the way your body handles load.
Sometimes the site of your pain isn’t the source of your problem.
Train the tissues that manage force and everything upstream benefits.
