When you hold a muscle squeeze until it gets tired, different parts of the triceps respond differently — especially depending on how your shoulder is positioned. One part (the long head) changes activity based on shoulder angle, but the others don’t.

The long part of the triceps doesn't work much when you push weights overhead because of how it's connected across two joints and how your shoulder moves.

If you're a guy who hasn't trained much before, your triceps muscle in the back of your arm grows about the same no matter if you do push-ups, triceps extensions, or a mix of both — the type of exercise doesn't really matter for this part of the muscle.

Pressing a barbell in front of your head works your triceps more than doing it behind your neck, because of how your body has to balance and where the weight is pulling.

If you're a guy who lifts weights and do bench presses on a flat or slightly angled bench with a medium-heavy weight, your triceps are working just as hard no matter the angle — changing the bench tilt from flat to steeper doesn't really change how much your triceps help out.

If you're used to lifting weights, your triceps work harder during shoulder presses when you use a barbell on a solid bench than when you use dumbbells on a wobbly ball — the more stable the setup, the more your main muscles have to engage.