Need a reason to skip Pilates class? Because we've got a good one: In 2015, a British woman with persistent headaches found that the reason for her pain was leaking brain fluid brought on by (you guessed it) a Pilates class. It typically takes some kind of trauma for brain fluid — a clear liquid that flows between the brain and spinal cord and their outer coverings — to leak. Trauma from car accidents, tumors and botched surgeries are all known to sometimes cause this problem. But in certain people, brain fluid leaks can occur spontaneously when too much pressure is put on the skull or spinal cord, which is probably what happened to the Pilates-performing patient with persistent headaches. After a standard treatment of bed rest, caffeine and ibuprofen, the woman recovered, according to a report published in the Journal of Medical Case Reports.