2. Your body involuntarily jerks from side-to-side

Another type of G-Force is "Lateral Gs", which occur when a ride races around a corner. This causes your body to be jerked suddenly sideways. It is possible for ride designers to reduce this effect by banking turns, but in some cases this is deliberately not done. The most obvious example is wild mouse-style roller coasters, which generally feature very sharp turns that are not banked. When these are in the dark, such as on Space Mountain at Disney's Magic Kingdom, the results can sometimes be a little painful.

1. Your heart pumps blood in the "wrong" direction

Typically, theme park rides that turn you upside down don't do so for long. Some of them, though, do leave you hanging for a little longer - such as the classic Ranger inverting ships manufactured by Huss. This is not dangerous in the same way as David Blaine's attempt to hang upside down for 60 hours was, but it is intriguing to think about what starts to happen while we're dangling there. Suddenly, our hearts don't have the benefit of gravity to help them. They are normally already beating faster when we're on a thrill ride, due to the excitement and fear that we experience. However, they now have to work double-time, pumping blood upwards to our legs and feet. Blood rushes to our heads and brain, causing red faces. There's nothing to worry about, though - our bodies scan easily cope with this in the short-term, and there's no danger of blood pooling in the lungs and head as there is with prolonged upside down stints.