As noted, we lose muscle mass with age. Especially quick to deteriorate are fast-twitch muscle fibers, which power quick, explosive movements.

如上而言，随着年纪的增大我们的肌肉会失去力量，尤其是快速收缩的肌肉纤维更为明显，这部分纤维让我们跑得快，启动有爆发力。

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Quick movements cause muscle stiffening. There is also a myotonic form of muscular dystrophy.

快速运动会引起肌强直，肌营养不良是另一种肌强直类型。

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The muscle contraction in humans are so lightning quick that the sentence 'building speed' just becomes absurd: We already have the ability, by physiology, to play at incredible speeds.

肌肉可以在一瞬间收缩因此‘提高速度’变得很荒唐。我们与生俱来这种弹得很快的能力。

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We let that one go, but only after he had held it in his hands, cold and quick, muscle with eyes and a heart, scales specked with yellow and red, and one tiny orange fin.

NEWYORKER: The Other Place