Sure, they're fast, but that's just used up in short bursts of energy. (mypetneedsthat.com)
In other words, it's the combination of caffeine with large amount of sugars that provide you with short bursts of energy. (fitnessandpower.com)
Slow twitch fibers are those used for longer endurance style workouts; and fast twitch fibers are those used for short bursts of energy such as sprinting, HIIT and plyometric workouts. (rachaelattard.com)