为什么身体走形之后想还原这么难？

Why Getting Back in Shape is So Hard?

为什么身体走形之后想还原这么难?

Because muscle memory doesn't last.

因为肌肉记忆不会持续。

Taking a month or two off of regular exercise may not be so benign. A new small study shows that when muscles take a break, they maintain very little muscle memory from the prior exercise.

把平常的规律性运动暂停1到2个月可不是个好习惯。一个新的小研究显示，当肌肉放松时，它只能保持很少之前运动时的记忆。

The goal of the new study, published Thursday in the journal PLOS Genetics, was to gain a better understanding of how exercise influences the body on a genetic level. As TIME recently reported, exercise carries a whole host of benefits for the body, from aging to brain health to a stronger ability to fight infections. But how that exercise translates to changes in genetic activity is more unknown.

现有一项于星期四在科学公共图书馆基因杂志板块发布的新研究，它的目标是：更好地理解锻炼怎样在基因层面上影响身体。《时代》杂志最近报道，锻炼完对身体大有益处，好处的范围包括延缓衰老、大脑健康、增强抵抗力。不过，这些锻炼究竟是如何影响基因活动的，依旧在很大程度上不为人知。

In the report, 23 people trained one of their legs for three months by kicking and pulling a bike-likecontraption 60 times a minute for 45 minutes. They did this training four times a week for three months.

报告显示，23个人通过坚持3个月，每天45分钟，每分钟骑60圈动感单车，来锻炼一条腿。每周锻炼4次。

After that, the people in the study took nine months off.

之后，他们休息了九个月。

The study authors took skeletal muscle biopsies from both legs before and after and found that the cells in the muscles expressed over 3,000 genes in different ways after a person exercised. However, after the fitness hiatuses, the scientists couldn’t detect any exercised-related genetic changes between the people’s trained and un-trained legs.

文章的作者前后分别对双腿做了骨肌活组织检查，并指出，锻炼之后肌肉细胞中的三千多基因发生了表达方式的变化。然而，健身活动停息后，科学家在锻炼过的和没锻炼过的两条腿之间，无法发现任何和锻炼有关的基因变化。

“We couldn’t see any differences at the gene activity level,” says study author MaléneLindholm of the KarolinskaInstitutet in Sweden. “Most effects are lost by a month or two of no training.”

“我们看不出基因活动层面有任何区别”来自瑞典卡洛琳斯卡学院的研究主导者马尔ž林霍尔姆说。“一到两个月不运动大部分的效果就消失了”

After that, 12 of the people in the study started training both of their legs. When the researchers compared biopsies of the two trained legs, they once again saw changes in genetic activity, but the leg that had undergone training nine months early looked virtually the same as the newly trained leg. “We did see some differences in the response but not substantial enough to claim some type of memory,” says Lindholm.

此后，研究中的12人开始锻炼他们的双腿。当研究者对比了双腿的活组织性检查结果时，他们再次看到了基因活性的改变，但是9个月之前锻炼过的那条腿和最近锻炼的这条腿看起来一样。“在结果中我们的确看到了些不同，但是不同的程度还不够去说明它是某种肌肉记忆”

Lindholm says the study could be interpreted in a couple ways. It underlines fact that exercise can spurhealthy biological changes, and that keeping up the practice is important to ensure those healthy changes are sustained. On the other hand, she says that the results can be encouraging to people who are sedentary. It suggests they can achieve the same benefits from exercise as anyone else. “The study could be used as positive encouragement,” says Lindholm. “It’s never too late to start training from a muscle perspective.”

林霍尔姆说这个研究可以通过许多方式去阐释。它强调了运动可以刺激健康的生理变化这一事实，而且坚持锻炼对于确保这些健康的变化能够保持是很重要的一点。另一方面，她说结果可以鼓励那些久坐的人。它说明他们可以和其他人一样从锻炼中获益。“这个研究可以算是一种积极的鼓励，”林霍尔姆说。“从肌肉的角度来说什么时候开始锻炼都不晚。”