We all want big arms, but getting them isn’t an easy task. Biceps are smaller muscles than, say, your quads, so it can take extra isolation work to really make them pop.

That’s why we love the biceps 21 routine. It’s a routine that forces you to do bicep curls three different ways for seven reps each. Ben Lauder Dykes, a trainer at Barry’s Bootcamp, showed us his own variation in the video above.

To start the routine, perform seven bicep curls from the middle of the lift to the top, so that at the bottom part of your lift, your forearm is roughly perpendicular to your upper arm. This is typically the hardest part of the bicep curl, so you’re going to do it first.

Then you’re going to perform seven full bicep curls. “Flex your triceps at the bottom,” says Launder Sykes, “and then all the way up. When you cannot get past this bit, it’s fine, then you do seven on the bottom where you’re stronger.”

Indeed, since there’s not a full range of motion, your last set of curls—from the bottom, arms fully extended, to halfway up your body—should be a cinch.

And there you have it: a fantastic bicep 21s variation that gives your bicep muscles a workout and gets those sleeves popping.

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