We’re going to do these with supination so that we’re invoking one of the main functions of the biceps, but that’s not the only twist. The dumbbell needs to sit in your hand in an offset weight distribution, meaning you won’t be grabbing the dumbbell in the middle of the handle, but with the thumb side flush up against the dumbbell plate.
This way, when you supinate, the short head has to work a bit harder against the offset resistance. (Supination makes the short head of the biceps work a little bit harder than the long head, and it’s the development of the short head that will make the biceps appear thicker when viewed from the front.)
The intensity technique we’ll use here is good ol’ drop sets, and my preference here is crazy 8’s. That’s 8 reps to failure, 8 reps to failure with a lighter dumbbell, and another 8 reps to failure with a still lighter dumbbell. Rest 2-3 minutes and do this 1 more time.