Something to keep an eye on if what was rare starts happening more often. Then the explanation becomes gaslighting.
Martial arts is a sport with no protection, no armor across the chest designed to deflect these impacts. It happens most often in baseball. While researching genealogy, I found a death certificate for a shoestring relative who was playing semi-pro on a rural farm team in the 1930s. He got hit in the chest by a pitch and died at home plate.