Although male kangaroos do appear to flex their muscles to show off their impressive figures, researchers in a 2013 study said it is not currently possible to determine whether or not such behavior is ...

A man who underwent the world's first full double arm transplant is celebrating being able to flex his biceps for the first time in over 20 years. Felix Gretarsson, 49, had to have his arms removed in ...

Dex Henderson shows us how to work the back and biceps in a circuit that will tone and give definition to you upper body in no time. Find out how you can Flex with Dex in one of his many classes, ...