Add Yahoo as a preferred source to see more of our stories on Google. Your favorite ab-building machine at the gym may be causing you more harm than good. That's right—we're talking about the torso ...

Stop wasting time on crunches and start training your core to resist movement for maximum power and injury prevention.

Depending on how you use them, strength training machines can be the key to stronger arms, powerful glutes, and heavier lifts. Or they can just waste your gym time while upping your risk of injury.

Our movement is not one-dimensional, so your workouts shouldn’t be either. Every day, your body bends, reaches, flexes, and extends—but it also twists, turns, and rotates. You do this when checking ...