Some rollercoasters reach G-forces which are more than what astronauts go through.
Serious brain injury
People should also be warned about the possible dangers of rollercoasters before they go on them, the doctors who did the study said.
They found the average risk of hurting yourself was one in every 124,000 rides. But the risk of a fatal injury was one in every 150m rides.
In the past 10 years, there have been 15 reported cases of people having serious brain injuries from rollercoasters, which have led to them dying.