Simplify the following text for a Grade 10 native English-speaking person.
Original: Two common variations on traditional winter biathlon are summer biathlon , where skiing is replaced by a cross-country run , and archery biathlon ( or ski archery ) , where the rifle is replaced by a recurve bow .
Simplified: Biathlon ( not to be confused with duathlon ) is a term used to describe any sporting event made up of two disciplines . However , biathlon usually refers specifically to the winter sport that combines cross-country skiing and rifle shooting .