Add Yahoo as a preferred source to see more of our stories on Google. The deltoids are the muscles that cover the front, back and side of the shoulder joint — and they are essential for everyday ...

Fun fact: The shoulder joint is the most flexible joint in the body because of its ball-and-socket structure, which allows for a wide range of movements. Shoulder mobility exercises and stretches can ...

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. Your shoulders are an ...