RFD is a fancy term for measuring how quickly an athlete can recruit the most muscle fibers. Muscle fibers are either slow twitch (Type I) or fast twitch (Type IIa or Type IIb). When muscle fibers are recruited, they’re always recruited from smallest to largest, so Type I gets recruited before Type IIa, which is recruited before Type IIb.
The best athletes in the world can go from the smallest fibers to the biggest fibers as fast as possible. Imagine a sprinter shooting out of the blocks.
Much like a car shifting gears, accelerating to top speed requires precise recruitment of muscle fibers. And going 0 to 60 is a lot easier when you’ve got more horsepower under the hood. That’s why building explosive strength with PAP methods is so beneficial.