To be a triathlete, you have to have a strong physique, or body-build.
Physique, pronounced "fiz-eek", is a word used to describe the form or shape of the human body. A person can have a muscular or well-toned physique. Often the word is used to describe a muscular or well-sculpted body. Do you have a hard, toned physique or a marshmallowy one? They both have their appeal.