When you bend your elbow, the muscles of the arm contract.

当你弯曲肘部时，手臂上的肌肉就收缩。

youdao

When you bend your elbow, you contract the muscles of the arm.

要从肘部弯曲手臂，就要收缩上臂正面的肌肉。

youdao

When you bend your elbow, you contract the muscles of the arm.

同时肘部轻轻弯曲，胳膊向后伸，这样你的肱二头肌就压在耳边了。

youdao

The idea was that the act of throwing a ball over a distance extended the arm muscles in a way that promoted strength and health at the same time.

WSJ: Dylan Bundy, Trevor Bauer, Matt Barnes: Throwing Long to Throw Short

The rotator cuff, a group of tendons and muscles connecting the upper arm to the shoulder blade, is also important to paddling.

WSJ: For the Love of Surfing and Wine Country

Our HAL was energized as soon as we tensed our arm muscles, so lifting up the tray of four 1.5kg water bottles was a piece of cake consistently throughout the demo -- we even managed it with just our pinky (see video above)!

ENGADGET: Cyberdyne HAL robotic arm hands-on (video) Hands-on