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3 Ways to Develop Fast-Twitch Muscles

Post-activation potentiation (PAP) is one of the best ways to trick your body into calling more fast-twitch muscle fibers into play on every rep.


Whether you’re into training for aesthetics, athleticism or both, you have dedicated yourself to the pursuit of maximizing human performance. Doing so clearly requires clean eating, beast-like training and smart supplementation. But a deeper understanding of how the body works is critical for developing a stronger, more powerful physique.

Yes, strength is accrued over time, but there are methods you can put to use in your very next workout to speed things along a smidge. Josh Bryant, MFS, CSCS, PES, founder of and author of Keto Built (Amazon, $15), has worked with hundreds of elite powerlifters and high-level bodybuilders. One tool he always puts to use is post-activation potentiation (PAP), a simple but effective hack that tricks your body into recruiting more of your power-and-strength-first fast-twitch muscle fibers on every single rep.

“Post-activation potentiation is a strategy used to improve performance in power activities and refers to the enhancement of muscle function following a high-force activity,” Bryant says. “Famed Russian sports scientist Yuri Verkhoshansky explained PAP this way: ‘When you perform a three- to five-rep max followed by a light explosive set, to your nervous system, it’s like lifting a half can of water when you think it’s full.’”

Put another way, performance is instantly increased because of previous muscle contractions. Remembering that your body is an adaptable organism, once it is subjected to a high-intensity activity, it wants to continue performing at that high level. So just let it.


A study published in the Journal of Strength and Conditioning Research found that sprint performance in rugby players improved after performing a heavy set (three reps at 90 percent of your one-rep max) of barbell squats. Unrelated activities, right? The beauty is that your muscles are as smart as you think. They interpret intensity with far greater ease than they do movement patterns.

This means that you can put PAP to work for you in many different ways, so long as you’re performing a higher-intensity activity followed by another less-intense activity.

Bryant offers these sample methods for maximizing the benefits of PAP.

Isometrics: “Do a maximal isometric contraction for six seconds before an explosive or heavy lift and you will perform the subsequent lift with more weight and speed,” he says. For example, if you try a set of isometric curls — curling a bar against a set of rack pins — and follow it immediately with a set of heavy (think six- to eight-rep max), full range-of-motion curls, you will find that you can rep out with greater ease.

Max, Then Rep Out: One strategy used by would-be NFL draftees at the Combine is PAP-driven. “Lift a heavier weight for a single before performing a max-reps activity,” Bryant says. “With the bench press, that could be a single rep at 300 pounds before getting under the bar for max reps at 225.”

Jump, Then Pull: The deadlift is a man-making lift that trains the entire body. Those who train it regularly find that gains come regularly and with ease — and that’s without PAP. Wanna crush your personal record? Bryant has a trick: “Do one to three max-height vertical jumps prior to your set of deadlifts.” He says this excites all the same muscle groups and convinces them to summon your heavy-hitter, fast-twitch muscle fibers into action on the reps that follow. This method also applies for the squat, Bryant says.