Do you do every set the same way? You know, same rep tempo, same hand spacing, same rest between sets?
Well, your motto for growth should be “change to gain” because it takes something unique to add more mass to your physique. Here’s a good example using seated biceps concentration curls:
Set 1: Do this set with supination—that is, start with your arm braced against your inner thigh, palm facing back at the bottom, and then twist your palm to face up as you curl. At the top, at peak contraction, your little finger should be higher than your thumb.
Set 2: Do all reps with your palm up—in the supinated position. In other words, don’t twist your hand.
Set 3: Go back to supinating, but do your concentration curls standing—Arnold style. He was also a big fan of supinating his hand—and he built some incredible biceps.
You can also change hand or foot placement on some exercises. For instance, on the calf machine start with your feet out wide for a set, and move them in a few inches for each successive set until your feet are close together.