If your fitness goal is to up the ante on endurance, pack more power into your sprint, or supercharge your strength gains in the gym, it’s worth exploring – what are the different muscle fiber types?

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.

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 ...