Musk’s Japanese steampunk-themed 42nd birthday party, Walter Isaacson explains (in his biography of Elon), culminated in a demonstration of Sumo wrestling:
At the end, the group’s 350-pound champion invited Musk into the ring. “I went full strength at him to try a judo throw, because I thought he was trying to take it easy on me,” Musk says. “I decided to see if I could throw this guy, and I did. But I also blew out a disc at the base of my neck.”
Ever since, Musk has suffered severe bouts of back and neck pain; he would end up having three operations to try to repair his C5-C6 intervertebral disc. During meetings at the Tesla or SpaceX factories, he would sometimes lie flat on the floor with an ice pack at the base of his neck.
Consider Musk to be the most remarkable human since the time of Leonardo [Da Vinci] I pose that question to everyone.