According to Gizmodo, the Journal of the American Osteopathic Association published a study this month by Michigan State University urologist David D. Wartinger and his team of crack researchers which presented evidence that riding moderate-intensity roller coasters can trigger the passage of small kidney stones.
"When a series of patients returned from spring break with stories of passing a kidney stone after riding the Big Thunder Mountain Railroad at Disney World in Orlando, I started to wonder if we had a unique opportunity to help patients," said Wartinger. "The moment one of my students and I realized we had to move forward was hearing from a patient who rode the ride three times and after each consecutive ride he passed a stone."
So, in the interest of furthering medical science, Wartinger and his colleagues concocted a plan that would be both scientifically illuminating and fun for all ages. First, they 3D printed an exact duplicate of said patient's kidney out of clear silicone. Then they filled the model with the patient's urine and dropped three kidney stones, all different sizes, into the model kidney's upper, middle, and lower passageways. Then they booked their tickets to Disney World.
Once at the Magic Kingdom and with the park's permission, they set about riding Big Thunder Mountain Railroad twenty or so times while holding the model kidney between them. Then they moved to Space Mountain and repeated the process. All in all, the intrepid scientists did 60 passes on the coasters, which isn't as fun as it sounds.
"As far as having to ride the coaster repeatedly, honestly, the first five to six times were great," said Wartinger."By the end we were just gritting our teeth and wishing to be done."
Data collected throughout the test showed some very interesting results. Testing in different cars on each ride produced various results, but the upshot seems to be that the powerful, random forces experienced by riders jarred the stones loose and guided them through the kidney's various branches until they could be expelled.