Even when you're not trying to bend your elbow, the muscle on the outside of your forearm feels stiffer if your palm is facing up than if it's facing down or straight ahead.

As you bend your elbow more and more, your forearm muscle gets looser — no matter if your palm is up, down, or sideways.

No matter how you turn your hand while bending your elbow, the brachioradialis muscle works about the same amount.

No matter how you turn your hand, the muscle on the outside of your forearm gets less stiff the more you bend your elbow.

When you bend your elbow by lifting something, the brachioradialis muscle works much harder pushing up than it does lowering the weight slowly.

When your palm is facing down and you bend your elbow slightly, your forearm muscle (brachioradialis) works harder than when your palm is up — it’s like your body uses this muscle more to help when your hand is in a 'handshake' position.