Functions: Developing the flexibility and endurance of arm.

功能：增强上肢耐力和灵活性。

youdao

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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The main physical qualities include the speed of moving and swinging the arm, flexibility and endurance.

身体素质以移动速度、挥臂速度、灵活性、耐久力为主要素质。

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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.

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