"There's a dramatic difference between what we think hurts people and what roller coasters do to people," says study co-author David F. Meaney, an associate professor of bioengineering at the University of Pennsylvania.
U.S. Rep. Edward Markey, D-Mass., who is pushing to make roller coasters safer, isn't so sure. In a statement, he points out that the study relies on mathematical models that create hypothetical humans.
"The 'average person' they are testing doesn't exist, but the people who have been harmed [by roller coasters] are very real," says David Moulton, Markey's chief of staff.
At issue is the possible harm posed by acceleration, deceleration and gravitational forces -- or "g-forces" -- that affect the bodies of riders of today's increasingly scary roller coasters.
G-forces are a normal part of life on earth, but they can become dangerous at high levels. Military pilots, for example, must be careful when they reach g-forces that could make them pass out by driving blood toward their feet and away from their brains, Meaney says.
On roller coasters, "the g-forces can vary throughout the ride," Meaney says. "As you go down to the bottom of a hill and start to straighten out, you feel as if you're being pressed into your seat. And as you go into turns, you can feel yourself being pushed to the side."
Some experts fear the growing levels of g-forces in newer roller coasters could rattle the brains of riders, causing serious injury or death. Markey's office says it has found 58 cases of head injuries caused by roller coasters and other thrill rides; eight were fatal.
In his research, Meaney and colleague Dr. Douglas H. Smith created a mathematical formula to test whether g-forces and other physical effects of riding roller coasters could harm the brain.
"We had test measurements from roller coasters that tell us what forces are being applied to the body," Meaney says. "You can construct a model that will tell you how the head will move in response to these forces and plug in numbers representing tall people, short people, males and females."
The findings appear in the October issue of the Journal of Neurotrauma.
According to the researchers, high g-forces only present major risks when they last more than an average of 43 seconds, but the high g-forces on roller coasters only last a few seconds. Also, Meaney says, the highest g-force level on roller coasters is about 6 or 6.5 Gs, while the simple act of plopping into a chair may cause a body to encounter a g-force level of 10 Gs.
Another possible risk factor, the whipping around of the head in a roller coaster due to acceleration, should not create health problems either, the researchers say.
"The levels of acceleration experienced by a roller coaster rider is about 10 times less than anything expected to create significant injuries," Meaney says.
Meaney does say that roller coasters could be dangerous for people already susceptible to brain injuries. He recommends that you don't ride one if you feel ill or out of sorts.
In his statement, Markey says the new study is "valuable," and he adds that he has asked the Brain Injury Association of America to review available research. Markey is pushing for the federal government to regulate the safety of roller coasters.
What To Do
For more details on Markey's efforts to regulate roller coaster safety, visit his Web site by clicking here. For more on amusement park safety, check the International Association of Amusement Parks and Attractions. For more on brain trauma, visit the Brain Injury Association of America.