There's a lot of talk about lean muscle compared to bulk muscle, but experts say it's not worth differentiating the two.

Skeletal muscle is the type of muscle that controls movement. Problems with these muscles can be minor, life-threatening, or ongoing problems that make it hard to perform basic daily activities.

Repeated exercise, or wasting, can change the way key genes work.

When you picture different athletes—marathon runners, gymnasts, and Olympic weightlifters, for example—you likely categorize them instinctively by their height, size, and build. But the differences in ...