It’s only six moves and you do each one lying on your back ...

Core training has always been part of military PT and fitness testing. From crunches to sit-ups, flutter kicks, leg tucks and plank poses, the U.S. military uses many exercises to test core strength.

You likely know that maintaining a strong core is important for your overall health and fitness. But finding the time—and resources—to build that necessary strength can be, well, challenging, ...