U.S., Aug. 14 -- On August 24, Mataelpino, a town in central Spain near Madrid , is holding its annual "Running of the Bulls" festival but with a twist. For the eighth year running, the bulls have been replaced with 3-meter wide, 200-kilogram polystyrene balls.

Considered one of the best events to attend in 2019 in Spain, the " Running of the Balls " or "Boloencierro" might sound like a tame affair but being trampled by 200 kilos of runaway mass bearing down on you - be it bull or ball - is no laughing matter, and participants risk serious injury and broken bones.

A change in Spanish law took place in 2017 relating to the banning of bullfighting in the Balearic Islands. This lead to more humane alternatives to such events as the Running...