If you're a healthy college-age woman doing light dumbbell presses, whether you're new to lifting or have lots of experience, it probably doesn't change how your chest, shoulder, and upper back muscles turn on during the exercise.

If young, healthy women do dumbbell presses with a light weight, the chest part of the exercise (bench and incline) works the main chest muscle more than the shoulder press — both when pushing up and lowering down. And bench and incline presses work that muscle about the same.

If a young woman does shoulder presses with light dumbbells, her upper back muscles work harder than when she does incline or flat bench presses — and the more she leans back, the harder those muscles have to work.

If young, healthy women do light dumbbell presses, the shoulder press works their front shoulder muscles more than the incline press, and that works more than the flat bench press—no matter if they're lifting or lowering the weight.

When young, healthy women do light dumbbell presses, their shoulder and chest muscles work harder when pushing the weight up than when lowering it — except for one part of the chest muscle, where the effort is about the same either way.

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.