Fitness: Why are pushups so hard, anyway?

Exercises fall in and out of fashion, just like skirt lengths and hairstyles. But one exercise has managed to weather the fickleness of popularity and secure a spot in almost every list of 10 top exercises.
Versatile and effective, the pushup is an upper-body exercise targeting the chest, shoulders and triceps. That said, anyone who has struggled through multiple reps knows they’re one of those exercises that everyone loves to hate. Yet whether you’re attempting a Rocky Balboa set of