PHILADELPHIA (WPVI) -- Shoshana shows us how to use some light weights and your legs to engage your core strength.

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.

The core gets a lot of attention when it comes to aesthetics. But your torso muscles—which include your abs, back, glutes, and hip flexors—play a crucial role in running that goes way beyond looks.

The path to core strength is as varied as the number of exercises that build your core system. There are hundreds of exercises from which to select when working to build the core, but this type of ...