**2.2. Experimental conditions**

We have classified the hardness of the sole of each footwear type during jogging on the basis of their subjective hardness: barefoot condition was interpreted as the maximum hardness, as the outer protection and reduction of the shock at the beginning of the stance phase was minimal. The own athletic shoes of each subject (typically used to run) was the condition interpreted as the softest. The standard shoes were harder than the athletic shoes, and therefore feature less cushioning of the impact.
