Beth Skwarecki is Lifehacker’s Senior Health Editor, and holds certifications as a personal trainer and weightlifting coach. She has been writing about health for over 10 years. While many types of ...

Try this quick experiment: While holding a cup in your hand, reach your arm out in front of you and hold that position for as long as you can. Your arm gets tired and burns after a while, doesn’t it?

When most people think of abdominal workouts, they picture intense movement. Sit-ups, leg raises, planks. But the truth is, your deepest core muscles often get left behind. Traditional exercises don’t ...