When guys who lift weights do shoulder presses sitting down with a kettlebell instead of a dumbbell that weighs the same, their shoulder and back muscles seem to work a bit harder — maybe because of how the kettlebell is shaped and balanced.

Using a kettlebell for overhead presses might make your shoulder and back muscles work harder than using a dumbbell, because the kettlebell's weight hangs below the handle and makes you stabilize more as you lift.

When guys who lift weights do the lowering part of a shoulder press, using a kettlebell makes the front shoulder muscle work harder than using a barbell — probably because the kettlebell is less stable and harder to control.

Using a heavier kettlebell during shoulder presses activates key shoulder-blade muscles way more than a light dumbbell — up to 72% more, according to this claim.

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.

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.