Everyone is familiar, at least hand-wavingly, with the distinction between slow-twitch and fast-twitch muscle-fiber types. The former are great for running marathons; the latter are ideal for ...

What's the first thing that comes to mind when you think about the words twitch and muscle? Spasms, perhaps. You'd hardly be alone in thinking that. But when it comes to fitness, it's most commonly ...

Tsukuba, Japan—Muscle fibers, which constitute skeletal muscle, are classified into two main types: slow-twitch (Type I, red muscle) and fast-twitch (Type II, white muscle). Slow-twitch fibers are ...