I can vouch for what's being said here. I've added 1/2 an inch to my arms since Jan this year and all I do are squats, T-bar rows, deads, chins, benches and OH presses.
Chins are an especially good arm movement because they work the bicep from both insertion points.

I seem to recall reading somewhere that a good rule of thumb is that to add a 1/2" to your arms you'll need to gain about 10lbs. Does that sound right???

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