And these basically fatigue very quickly. So that means when we're sprinting and that requires let's say, 10 seconds, these are the muscles that we're going to use. So because we don't have too many capillaries, we don't have too much oxygen. That means we don't have too many myoglobin carrier proteins. And so these muscles will appear white. So these are known as the white muscles, but these two muscles are known as the red muscles because these have a fast contractile rate.