Building your fast-twitch muscle fibers can help you get stronger and faster. This type of muscle fiber is responsible for the fast, explosive movements used in activities like sprinting, jumping, and ...

Doctors identify these movements as 'fasciculations', because they occur when individual nerve fibers, which control small muscle groups activate independently to produce brief muscle contractions.

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 ...