Then there’s the secretive Tarahumara tribe, the best long-distance runners in the world. These are a people who live in basic conditions in Mexico, often in caves without running water, and run with only strips of old tyre or leather thongs strapped to the bottom of their feet. They are virtually barefoot.

Come race day, the Tarahumara don’t train. They don’t stretch or warm up. They just stroll to the starting line, laughing and bantering, and then go for it, ultra-running for two full days, sometimes covering over 300 miles, non-stop. For the fun of it. One of them recently came first in a prestigious 100-mile race wearing nothing but a toga and sandals. He was 57 years old.

Running barefoot, anyone?