Roller Coaster G Forces Safe for Most

Oct. 16, 2002 -- Buckle up, there's more news about roller coasters. This time, researchers debunk all the concern about injuries caused by G forces.

Current roller coaster rides do not produce high enough forces to deform and injure the brain, writes Douglas H. Smith, MD, a neurosurgeon at the University of Pennsylvania in Philadelphia.

Blood vessel abnormalities in the brain or high blood pressure caused by excitement are likely to blame for injuries, he says.

Smith's NIH-funded study appears in this week's Journal of Neurotrauma.

"There has been enormous attention in the general press on the possibility that high G force roller coasters are inducing brain injury in riders," he writes. "Armed with a handful of anecdotal case reports of brain injuries, the U.S. Congress has recently proposed legislation to regulate the level of G forces of roller coasters."

However, high G forces are not the issue, says Smith. "Rather, accelerations of the head that can be caused by G forces are the key to producing injury."

Smith's colleague David Meaney, PhD, of Penn's department of bioengineering adds, "When we predict head acceleration in roller coasters -- the sudden twists and turns -- we find that they are all within established safety margins. It does not appear that roller coasters produce a high enough force to mechanically deform and injure the brain."

"Roller coasters apply only brief accelerations in different directions throughout the ride, with little chance of inducing unconsciousness from pooling of the blood in the extremities," he says. Also, "high G's of short duration are common and well tolerated in many daily activities, such as hopping off a step or 'plopping' into a chair, where eight to ten G's have been measured."

In his study, Smith used a mathematical model of head rotational acceleration and factored in G force data from three popular high-G roller coasters.

The G-force data on "Rock 'n' Roller Coaster" at the Disney-MGM Studios in Lake Buena Vista, Fla., "Speed --The Ride" at the Nascar Café in Las Vegas, and "Face-Off" at Kings Island, Ohio, were the focus of the study.

"Even for a conservative worst-case scenario, we found that the estimated head rotational accelerations experienced by roller coaster riders are nowhere near the range of established injury thresholds for severe forms of brain injury," Smith writes.

To injury the brain, it would take 18 times more head acceleration than he calculated for roller coaster riders, he adds.

All his studies apply to normal, healthy people, Smith says. Some people may have a reduced tolerance to head accelerations, which may account for case reports of injuries. And some cases of brain damage apparently caused by roller coasters were actually the result of previous brain injury.

However, injury to malformed blood vessels in the brain can occur during many activities that do not mechanically deform the brain. Hypertension from excitement of the ride should also be considered, he adds.

The bottom line: "We highly recommend that all roller coaster riders use a proven method to reduce the risk of brain injury: make sure your seatbelts are buckled at all times when driving to an amusement park." -->