That tiny timing change matters because a push-up is not just a chest exercise. It trains the chest, triceps, shoulders, core ...

The push-up is a basic exercise that almost everyone has done—or at least tried to. Push-ups can be done with minimal space and zero equipment, making it a popular and effective bodyweight move.

Push-ups are one of those classic exercises you see everywhere, from bootcamps to yoga flows to strength workouts—and probably even in your gym class flashbacks. But if you find yourself grimacing ...