Using the force.

When braking, an F1 driver handles up to 5G on their body, that’s more than double the g-force you feel when crashing your car into a wall at 100km/h.

Text Source: http://www.news.com.au/technology/design/six-things-you-didnt-know-about-formula-1/story-fnjwucvh-1226856241458