Researchers at Michigan State University's College of Osteopathic Medicine built a validated silicone kidney model, loaded it with three real stones from the patient whose CT scan it was based on, and rode the Big Thunder Mountain Railroad coaster with it twenty times to test the claim.
Riding in the rear of the train, the stones passed out of the model in 23 of 36 attempts; in the front of the train, they passed in only 4 of 24. Stones sitting in the upper part of the kidney passed every time from the rear seat, while stones lower down passed 40 percent of the time.
The rougher, more jarring motion felt at the back of the train appeared to matter more than speed or height, since front-seat riders experienced the same drops with far less shaking. The researchers suggested the vibration and g-forces could dislodge small stones and proposed roller coasters as a low-cost option worth discussing for some patients, though it has not replaced standard medical treatment.
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A theme park ride, moving kidney stones along.
Source
- Mitchell, M. A., & Wartinger, D. D. (2016). Validation of a Functional Pyelocalyceal Renal Model for the Evaluation of Renal Calculi Passage While Riding a Roller Coaster. The Journal of the American Osteopathic Association, 116(10), 647–52. https://doi.org/10.7556/jaoa.2016.128