July 1, 2002 -- There's nothing like the highs and lows, the twists and turns, the thrills and that weightless feeling you can only find on a high-tech, fast-paced roller coaster.
Over 300 million people flock to theme parks in the United States annually, and each year, these screaming, shrieking fans are seeking a bigger, faster, and wilder ride than the one they went on the year before. But after taking one look at these 300-foot-tall structures, you don't have to be a worried mom to wonder: How fast is too fast, and is "safe" safe enough?
Dr. Jamshid Ghajar, a neurosurgeon at Weill Medical College of Cornell University in New York, and president of the Brain Trauma Foundation, said that there are risks associated with roller coasters, but the likelihood of injury is relatively small.
"In terms of the number of injuries, they see one in every 15 million riders," Ghajar told Good Morning America. "In terms of deaths, there are one in 150 million. You are more likely to suffer a serious head injury driving to and from the park."
But there is growing concern about the force of gravity that is exerted on people as they ride these faster roller coasters. In October, New Jersey will become the first state to limit G-forces on rides.
Meanwhile, the American Association of Neurological Surgeons, has assembled a national committee of neurosurgeons, NASA scientists and engineers are looking at how the stress of G-forces from roller coasters might affect our brains, Ghajar said.
"They are looking at the force applied to the brain at various G-force levels, and how the brain is moved around on these rides," he said. The committee has not reached any conclusions yet. But one of the major causes of brain trauma is a kind of tossing of the brain, in which it is bounced around inside the skull, and injured.
Playing With G-Forces
Even though the brain is protected by the skull, and is surrounded by liquid that cushions it, rapid movement can be dangerous. Yet not completely restraining the head on rides can be dangerous, too, because it could place more force on the spine, and lead to more spinal injuries, Ghajar said.
With speeds topping 80 mph, roller coasters exert a higher force of gravity, or G-force, on a rider's body compared to what they normally experience. When you are on the ground, you are essentially neutral, at 1G, but some newer rides will increase the force of gravity on your body up to 6 G's for seconds at a time. At 6 G's, a typical 170-pound rider will feel as though they weigh over 1,000 pounds, or six times heavier.
The rider experiences a sinking feeling as he accelerates, and as the ride turns, it may throw his head from side to side, leaving the brain vulnerable to injury.
"It's how the head is moved because of the G-Force," said Douglas Smith, an associate professor of neurosurgery at the University of Pennsylvania. "So the head moves rapidly, the brain is changing shape or deforming inside the skull, there might be compressive or stretching types of forces on the brain. If that occurs rapidly, then you can have injury."
With the new regulations in New Jersey, those who design roller coasters are doing some careful calculations.
"We're looking at G-forces from the standpoint of onset," said Jim Seay, a roller coaster designer. "Which means how quickly you feel the G-force and how quickly that G-force is taken off of you. And for duration, you are only experiencing G-forces on rides for very short periods of times. We're talking seconds or split seconds."
Who Is at Risk?
Roller coaster enthusiasts can never be 100 percent protected on rides, but from what experts know now, people with pre-existing conditions are at the greatest risk for injury, Ghajar said. Generally the risks apply to older people more than children, because they are more likely to have such conditions. So as long as children obey the rules of the ride, they should be fine, Ghajar said.
The rides increase blood pressure and heart rate, so those with high blood pressure or heart problems would be wise to stay off the rides. People with spinal injuries are at greater risk for exacerbating those injuries, Ghajar said. Anyone who has or has had brain aneurysms or a stroke should also avoid the rides.
Children who ride multiple times are not really at any greater risk compared to one-time thrill seekers, Ghajar said.
"If there is no pre-existing condition, the number of times they ride isn't proven to increase risk," Ghajar said. "You should just be aware if the kid gets off the ride with a headache or disorientation, they should be medically checked, and not sent back on the ride."
Some people who suffer brain injuries seem fine for hours or days, and then end up collapsing. Several months ago, a 13-year-old girl died of brain swelling two days after she was hit in the head with a hockey puck at a game.
That case was rare, Ghajar said. Most people who suffer a brain injury will have severe headaches, dizziness, sleepiness or confusion. Overwhelmingly, people will exhibit one or all of these symptoms, and should immediately have it checked out, especially if they have just been on a ride.
"If you feel something like a bad headache, or confusion, or dizziness when you get off the ride, get it checked out," Ghajar said.