“Scientists speak of “transient hypofrontality”: a state-of-mind promoted by pursuits that require physical exertion but little thought or concentration. The parts of the brain that coordinate general concepts and rules are turned down, while the motor and sensory parts are turned up. In this state, ideas and impressions mingle more freely. Unusual and unexpected thoughts arise.”
Source: If Exercise Was Good For Charles Darwin, It’s Good For All Of Us, via The Guardian, published January 1, 2014.