You've probably heard that you should feel a certain muscle working when you do an exercise. Your biceps should burn a little ...

A new study explains how a tiny enzyme switch helps muscles make energy during exercise and may even connect to diabetes risk ...

Muscle knots are highly irritated muscle fibers that have tightened into a ball in one area of your muscle. These painful, tender spots can feel sore and often occur in your upper back, shoulders, or ...

Muscle cramps are a common issue that many people get from time to time. If one of your muscles feels like it’s contracting (getting tight) for no reason — and you can’t get it to relax — that’s a ...

Without realizing it, many of us start our day by stretching before we even get out of bed. Involuntary stretching of your muscles is called pandiculation. It’s a behavior seen in most types of ...

Muscle fatigue is a decreased ability to create force with your muscles. Electrolyte imbalance and overuse are some of the most common causes of muscle fatigue. Rest and massage are the best ways to ...

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. You've probably heard ...