There are visceral reactions most of us expect during a roller-coaster ride: a drop in the gut, a leap of the heart, a tingle in the fingertips.
For some, there may be other feelings, too: a pang in the back, a kick to the lower abdomen, an urgency in the bladder. These are symptoms that often come with passing a kidney stone — an event that may not be entirely unexpected on certain roller-coasters, according to a new study.
The authors found that moderate-intensity, rattling coasters might be effective at dislodging little kidney stones in the outer ducts of the kidney and propelling them toward the ureter, the tube connecting the kidneys and bladder.
Their report, published last week in The Journal of the American Osteopathic Association, suggests that riding these roller-coasters might help patients who have kidney stones that are five millimeters or less in diameter.
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“The idea is to displace these little stones before they become big stones and cause a lot of pain and suffering,” said Dr. David Wartinger, a professor emeritus at Michigan State University who was an author of the study.
Wartinger said he was inspired to do the study after seeing multiple patients who had passed kidney stones after going to an amusement park. Most notable, one patient passed kidney stones after each of three consecutive rides on the Big Thunder Mountain Railroad roller-coaster at Disney World in Florida.
He teamed with Marc Mitchell, a urologist at the Doctors Clinic, to create a 3D-printed silicone cast of a patient’s kidney. The researchers filled their life-size model with kidney stones and urine and headed to Disney World.
Holding their model at kidney height, the doctors took 20 rides on Big Thunder Mountain, with three stones in the model at a time. They saw kidney stones move from the periphery of their kidney model toward the top of the ureter in many cases. Success rates were higher in the back of the roller-coaster than the front — 64 percent versus 17 percent — probably because a bumpier ride in the back meant more jostling.
More than 300,000 Americans seek emergency care for kidney stones a year, mostly because of severe pain from having a large kidney stone stuck in their ureter. It’s unlikely that a roller-coaster ride would do them much good.
“This study is really designed for people who have these very small stones,” said James Borin, a urologist and assistant professor at New York University not involved in the study.
For now, if you know you have a small kidney stone and want to give the roller-coaster treatment a try, talk to your urologist. You just might be able to get rid of a kidney stone while also having some fun — and one could call that killing two birds.