The contraction of muscles USES energy and releases heat.

肌肉的收缩消耗能量并且释放热量。

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Since the lymph flows very slowly with the contraction of muscles, the stimulation of current can help to quicken its speed.

淋巴系统中的淋巴液，流动非常缓慢，随着肌肉的收缩而流动的，所以电流刺激会帮助淋巴循环的舒畅。

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But focusing on close objects involves contraction of muscles controlling the shape of the eye's lens. And one possibility is that "this constant contraction may stretch the eyeball.

目前没有研究显示为什么大量阅读会导致这一结果，但是由于长时间聚焦近处的物体需要眼部肌肉持续收缩以保证视网膜保持需要的形状，因此这种眼肌的持续收缩状态可能会使眼球受到拉伸，长期如此，其原有形状可能会被永久地改变，从而导致近视产生。

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This latest theory, originally published in the journal BioEssays and reported in New Scientist magazine, says the key to hiccuping lies in a group of animals for whom combining closure of the glottis and contraction of the "breathing in" muscles does serve a clear purpose.

BBC: Why we hiccup

The buildup of acetylcholine makes it impossible for muscles to relax in between neurological messages and they go into a state of continual contraction.

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