There are no flip turns to negotiate in marathon swimming, which is usually held in lakes and oceans, and the upper body is more important than the legs.

这种马拉松式游泳一般在湖泊或海洋中进行，不需要突然发力和转身，而且上半身的动作比腿部更关键。

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Concerns shave also been raised over the viral load found in the water off Copacabana Beach, which will host the marathon swimming, and also in the sand itself.

科帕卡巴纳海滩的水域将举办马拉松游泳项目。而水域和沙滩的病毒含量也令人担忧。

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Marathon, US: a dolphin at the dolphin Research Centre waits to be fed fish while swimming in a pen, as he acclimates to his new surroundings after being found.

美国，马拉松：一个海豚研究中心的海豚在池子里游泳的时候等待喂食，他已经适应了这儿的新环境。

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Marathon swimming is so new that it's hard to obtain data on splits or compile any convincing evidence about strategy.

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Nyad's marathon swimming career began in July 1970, when she set the women's world record for the 10-mile swim across Lake Ontario: four hours and 22 minutes.

CNN: Nyad delays attempt to break distance-swim record

When it comes to marathon swimming, there's an even stronger argument for staying with the pack: It allows you to prevent others from drafting off you and preserve their strength at your expense.

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