So in order to move your hand through water which is a much heavier medium than air, it will require more strength - to do that over time requires endurance of your arm muscles.

就像在第一点提到的，这要根据你的划水频率和在水里移动手臂的能力决定，牵涉到力量和耐力。 因为水的密度比空气大很多，不断地划水需要你手臂肌肉很好的耐力。

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For great power always belonged to thee alone: and who shall resist the strength of thy arm?

你随时可用你的大能，有谁能抵抗你有力的手臂？

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She's balancing herself on the strength of a single arm.

她仅用一只手臂的力量保持着整个身体的平衡。

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But as the Giants pick through the 107 players assembled here to see which of them, if any, they ought to consider drafting in April, they are one of the few teams that won't spend too much time scrutinizing the mechanics or arm strength of the quarterbacks on show.

WSJ: The New York Giants Are Looking for Something Boring in the Draft

This measures not only the accuracy of a pitcher's arm but also its strength: The more victories a hurler has, the greater his endurance.

FORBES: The Best Pitchers For The Money

"The goal is to develop techniques for using the strength of the legs and torso to help power motions of the arm, " posted the company underneath the video.

BBC: BigDog four-legged robot now sports throwing arm