Riding on some types of rollercoaster is an effective way to remove kidney stones.
This is the result of research that has won this year's Ig Nobel Prize for Medicine.
The US researchers who did the work recommend that those suffering from the disease regularly use the theme park's attractions.
The Ig Nobels are spoof prizes that acknowledge achievements that make people laugh but also think for a moment.
Many of the topics recognized in the awards actually have a serious point for them.
The inspiration behind roller coaster research began several years ago when one of Prof. David Wartinger's patients at Michigan State University's College of Osteopathic Medicine returned from a vacation trip to Walt Disney World in Florida.
The patient reported that one of his kidney stones had slipped off after driving on Big Thunder Mountain.
Whether it was caused by the ride or a coincidence, the patient went several times and each time a stone jumped out.
Fascinated by the story, Prof. Wartinger built a silicone model of his patient's kidney system, including artificial kidney stones, and took it on numerous trips.
He discovered that the Big Thunder Mountain was indeed effective – more than the creepier rides like Space Mountain or Rock and Rollercoaster that brought longer drops.
Prof. Wartinger came to the conclusion that Big Thunder Mountain involves more ups and downs as well as lateral movements that "rattle" the rider.
The Medical Award is one of 10 Ig Nobels awarded every year for amusing and congenial science. They are all real studies and almost all have been published in journals.
At the awards ceremony at Harvard University in Cambridge, USA, each winner has 60 seconds to give a speech of thanks. The time limit is enforced by an eight-year-old girl who says "please stop, I'm bored" several times until the speaker is done.
Medical education: Scientists are sometimes roughly described as "their own buttocks" if they are too obsessed with their research.
However, in the truest sense of the case, this is the case with the Japanese researcher Dr. Akira Horiuchi, who received the medical education award for developing a self-colonoscopy technique with a small endoscope.
"Luckily, I did not find any polyps or cancer," he told BBC News.
"This experiment may be funny, but I've introduced an endoscope for a serious purpose in my colon.
"People, especially in Japan, are scared of colonoscopy and do not want to do colonoscopy, so the number of people dying from colorectal cancer is increasing and I'm doing this research to make colonoscopy easier and more comfortable so that fewer people die ".
Literature: This year's Literature Prize was used to investigate consumer instructions for consumer products. The study was called "Life is too short for RTFM": how users relate to documentation and redundant functions.
"RTFM" is an acronym for "read the field handbook," although researchers have found new meaning in consumers, who are often frustrated by the complexity of running their product.
Nutrition: A British researcher won the nutritional prize for calculating this pound per pound, it's not worth eating human meat compared to other meats. This should analyze the eating habits of early humans instead of influencing today's eating habits.
Economy: For the economy, the winner was research that examined whether it is effective for employees to use voodoo dolls to avenge mobbing bosses. This study showed that losing weight from dolls relieved negative feelings, but in the long term suggested that it was better to deal with the underlying problem.
Chemistry: The winner of the Ig Nobel Chemistry Award went to research that clarified the question of whether human saliva is a good cleaner for dirty surfaces. It is – especially for fragile, painted surfaces on ceramics and on gold leaf.
Biology: A Swedish team has won the Biology Ig Nobel because it shows that wine experts can reliably identify the presence of a fly in a glass of wine by smell – possibly a new genre of jokes involving sommeliers.
Peace: Last but not least, the Ig Nobel Peace Prize went to a Spanish group whose aim was to find ways to reduce street rage in a newspaper called Screaming and Cursing While Driving: Frequency, Reasons, Perceived Risk and Punishment. The team's solution is to reduce stress and enhance traffic safety campaigns – a task as great as reducing conflicts in the Middle East.
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