If you're a healthy guy doing seated shoulder presses with heavy weights, using dumbbells probably works your front shoulder muscles a bit more than using a barbell.

If you're a healthy guy doing dumbbell shoulder presses, sitting down might work your rear shoulder muscles a bit more than standing up—about 15% more, according to muscle activity readings.

When healthy guys do shoulder presses, standing with dumbbells makes their shoulder muscles work harder (based on electrical activity), even though they can lift heavier weights when sitting with a barbell.

If you're a guy who lifts weights, the shoulder press works your front shoulder muscle more than bench presses, flys, or lateral raises when doing a typical workout.

If you're a guy who lifts weights, doing shoulder presses works your front shoulder muscles way more than bench presses, flys, or lateral raises. It's one of the best moves to really fire up those front shoulders.

When competitive male bodybuilders do overhead presses with a free barbell instead of a machine, their side and rear shoulder muscles work harder because they have to balance the weight themselves.