It was all Wiki stuff I copied, thank them! lol^_^ Anyway, I response to your question, well what do you know, good 'ol Wiki is here to answer a few questions!!! lol
Rikishi (力士) is a term most commonly used to describe a professional sumo wrestler. The Japanese characters making up the name literally mean "strong man", which is highly appropriate given the size and strength required to participate in this sport at the highest level.
During their active careers rikishi live in "stables" run by a trainer, who is always a former sumo wrestler himself. The life can be quite strictly controlled, and for junior wrestlers, would by today's standards in Japan (or in the west) be considered quite harsh