An underused method to increase muscular force output and growth-inducing TUT (time under tension) is programming specific tempos into your pull-ups. In order to recruit a maximal number of fast-twitch muscle fibers, make the concentric contraction (the pulling UP part) as explosive as possible as your chest approaches the bar.
At the top of the movement, squeeze for 1-2 seconds to maximize TUT and force output in the shortened state of the biceps, lats, and upper posterior-chain musculature.
Control the eccentric or lowering portion of the movement by trying to "press" yourself back down into a full tensioned hang. The tempo I recommend for strength and hypertrophy is X120. In tempo lingo, that means:
- Explode up as your chest moves toward the bar.
- Hold isometrically at the top for one second.
- Take about two seconds to lower your body.
- With no pause, come back up for another rep.