🎯 The Regional Growth Hack — Why Preacher Curls Build a Different Bicep

Most lifters treat all curls as interchangeable, but a landmark 2025 study proved otherwise: preacher curls produced up to 60% more growth in the lower biceps compared to incline dumbbell curls, while incline curls built more of the upper bicep instead — this is called regional hypertrophy, and it means different curl angles genuinely grow different parts of the same muscle. That's exactly why the "Squeeze at the Top" cue in the image matters so much for the preacher curl specifically — EMG research confirms this exercise produces its highest biceps activation only in a narrow window near the top of the rep, unlike a standard curl where tension stays more evenly spread through the whole range.

The angled pad locks your upper arms in place so your shoulders can't cheat, which is precisely what forces the short head of the biceps, the part responsible for that "peak" shown in the zoomed panel, to do all the work instead of momentum bailing you out. The second half of the hack, "Control the Lower," is just as critical: a 2-3 second controlled eccentric loads the biceps in its most stretched, vulnerable position at the bottom, which is where the muscle experiences its greatest mechanical tension and the real growth signal actually happens.

Never let your elbow lift off the pad and stop just short of a full lockout at the bottom — locking out fully hyperextends the elbow under load, exactly the mistake that turns this build-a-peak exercise into a joint-strain risk. Combine both cues into every single rep, pause and squeeze hard at the top, then fight gravity all the way back down, and you'll finally carve that dense, high peak that separates good arms from great ones 💪

For a legend whose thick, peaked arms were built through this exact kind of brutal, no-shortcuts intensity, check out Branch Warren - Train Insane, available now at Prime Cuts Bodybuilding.