健康生活:运动前不宜拉伸

Most of us grew up hearing that we should warm up with a stretch. Strike and hold a pose, such as touching your toes, for 30 seconds or more, we were told, and you'll be looser, stronger and injury-proof.

我们是听着这样的告诫长大的：运动前要先做拉伸运动来热身。摆出姿势并保持——比如用手触脚尖——30秒或更久，然后我们的身体就可以变得更柔韧、强壮、不易受伤。

But anyone who follows fitness science — or this column — knows that in recent years a variety of experiments have undermined that idea. Instead, researchers have discovered, this so-called static stretching can lessen jumpers' heights and sprinters' speeds, without substantially reducing people's chances of hurting themselves.

不过，所有关注运动科学（或本专栏）的人都知道，近年来有不少实验都证明，运动前拉伸并不高明。研究者发现，所谓的静态拉伸会让跳高运动员跳得更低、短跑者跑得更慢；而且还不能显著降低运动受伤的风险。

Now, two new studies are giving us additional reasons not to stretch.

现在，又有两个新研究为我们提供了“不要拉伸”的新理由。

One, a study being published this month in The Journal of Strength and Conditioning Research, concluded that if you stretch before you lift weights, you may find yourself feeling weaker and wobblier than you expect during your workout. Those findings join those of another new study from Croatia, a bogglingly comprehensive re-analysis of data from earlier experiments that was published in The Scandinavian Journal of Medicine and Science in Sports. Together, the studies augment a growing scientific consensus that pre-exercise stretching is generally unnecessary and likely counterproductive.

其中一项发表在本月的《力量与训练研究杂志》(The Journal of Strength and Conditioning Research)上。研究称：假如你在举重前进行拉伸运动，你会感觉举的时候比预期力气更小、踉踉跄跄。此结果与另一项由克罗地亚科学家对以往实验进行的广泛深入的再次分析不谋而合，该项研究发表于《北欧医学与运动科学杂志》(The Scandinavian Journal of Medicine and Science in Sports)。这两项研究巩固了一个日益强大的科学共识：通常情况下，在锻炼前做拉伸不仅没必要，还可能起反作用。

Many issues related to exercise and stretching have remained unresolved. In particular, it is unclear to what extent, precisely, subsequent workouts are changed when you stretch beforehand, as well as whether all types of physical activity are similarly affected.

锻炼与拉伸之间的很多关联尚不明朗。特别是：人们不知道准确来说，拉伸到什么程度会使接下来的锻炼受到影响；也不知道是否锻炼前拉伸对一切体育活动都产生相似作用。

For the more wide-ranging of the new studies, and to partially fill that knowledge gap, researchers at the University of Zagreb began combing through hundreds of earlier experiments in which volunteers stretched and then jumped, dunked, sprinted, lifted or otherwise had their muscular strength and power tested. For their purposes, the Croatian researchers wanted studies that used only static stretching as an exclusive warm-up; they excluded past experiments in which people stretched but also jogged or otherwise actively warmed up before their exercise session.

为了让新研究涉及范围更广，同时解释上述问题，克罗地亚萨格勒布大学(University of Zagreb)的科学家梳理了上百个以前进行过的实验。这些实验中，志愿者先做拉伸运动，然后或跳、或扣篮、或举重或进行肌肉强度与力量测试。基于研究目的，他们只选择用静态拉伸作为唯一热身运动的实验；剔除了那些让志愿者在锻炼前除拉伸外还慢跑过或做过其他动态热身的实验。

The scientists wound up with 104 past studies that met their criteria. Then they amalgamated those studies' results and, using sophisticated statistical calculations, determined just how much stretching impeded subsequent performance.

最后，符合他们选择标准的共有104项研究。他们综合这些研究的结果，利用复杂的统计计算方法确定拉伸对锻炼的影响程度。

The numbers, especially for competitive athletes, are sobering. According to their calculations, static stretching reduces strength in the stretched muscles by almost 5.5 percent, with the impact increasing in people who hold individual stretches for 90 seconds or more. While the effect is reduced somewhat when people's stretches last less than 45 seconds, stretched muscles are, in general, substantially less strong.

统计数字——尤其是对于竞技型运动员的数字——发人深省。计算结果是：静态拉伸让拉伸后的肌肉强度下降约5.5%；进行过90秒以上拉伸活动的人下降程度更大；若短于45秒，则影响减轻。总体而言，拉伸过的肌肉强度普遍减弱。

They also are less powerful, with power being a measure of the muscle's ability to produce force during contractions, according to Goran Markovic, a professor of kinesiology at the University of Zagreb and the study's senior author. In Dr. Markovic and his colleagues' re-analysis of past data, they determined that muscle power generally falls by about 2 percent after stretching.

同时，肌肉的力量也会变差。该研究的通讯作者、萨格勒布大学运动学教授葛兰·马尔科维奇(Goran Markovic)将肌肉力量解释为肌肉收缩时产生力量的能力。他与同事对过去实验的再分析得出结论：拉伸后，肌肉力量降低约2%。

And as a result, they found, explosive muscular performance also drops off significantly, by as much as 2.8 percent. That means that someone trying to burst from the starting blocks, blast out a ballistic first tennis serve, clean and jerk a laden barbell, block a basketball shot, or even tick off a fleet opening mile in a marathon will be ill served by stretching first. Their performance after warming up with stretching is likely to be worse than if they hadn't warmed up at all.

还有一个结果是：肌肉的爆发力亦显著降低——最高可达2.8%。也就是说，想从起跑线上立即起跑、将网球猛击出去、挺举杠铃、篮下盖帽、飞奔过马拉松第一程的人，都被拉伸“坑苦了”。他们以拉伸运动来热身比完全不热身表现得差。

A similar conclusion was reached by the authors of the other new study, in which young, fit men performed standard squats with barbells after either first stretching or not. The volunteers could manage 8.3 percent less weight after the static stretching. But even more interesting, they also reported that they felt less stable and more unbalanced after the stretching than when they didn't stretch.

另一项新研究得到了类似结论。实验中，年轻健壮的男性志愿者被要求拉伸或不拉伸后做标准蹲举杠铃的动作。拉伸后，志愿者能举起的杠铃重量比不拉伸时轻8.3%。更有意思的是，志愿者们表示，他们觉得拉伸后比不拉伸时重心更不稳、身体更不平衡。

Just why stretching hampers performance is not fully understood, although the authors of both of the new studies write that they suspect the problem is in part that stretching does exactly what we expect it to do. It loosens muscles and their accompanying tendons. But in the process, it makes them less able to store energy and spring into action, like lax elastic waistbands in old shorts, which I'm certain have added significantly to the pokiness of some of my past race times by requiring me manually to hold up the garment.

为什么拉伸会影响运动能力，这两项新研究的作者还不清楚，尽管他们怀疑部分原因是拉伸的确起到了我们所期望的效果：让肌肉与肌腱松弛。然而，拉伸也让肌肉储存能量和做爆发性动作的能力变差，就好比旧短裤上的松紧带一样——我敢肯定它害得我之前的跑步比赛用时过长，因为我要提着裤子赛跑。

Of course, the new studies' findings primarily apply to people participating in events that require strength and explosive power, more so than endurance. But "some research speaks in favor" of static stretching impairing performance in distance running and cycling, Dr. Markovic said.

马尔科维奇教授说：当然，新研究的结果主要适用于那些参加需要肌肉有强度和爆发力的比赛、而非耐力比赛的人们。不过有些研究也支持静态拉伸不利于长跑和远距离自行车运动的说法。

More fundamentally, the results underscore the importance of not prepping for exercise by stretching, he said. "We can now say for sure that static stretching alone is not recommended as an appropriate form of warm-up," he said. "A warm-up should improve performance," he pointed out, not worsen it.

从根本上讲，研究结果强调了不要在锻炼前进行拉伸类准备活动的重要性。马尔科维奇教授说：“我们可以确切地说：仅仅做拉伸运动并不是热身的好办法。热身运动应该提高运动能力。”他指出，热身不应当使运动表现变糟。

A better choice, he continued, is to warm-up dynamically, by moving the muscles that will be called upon in your workout. Jumping jacks and toy-soldier-like high leg kicks, for instance, prepare muscles for additional exercise better than stretching. As an unscientific side benefit, they can also be fun.

他继续讲道：“动态热身才是更好的选择。事先活动一下即将利用到的肌肉。比如开并腿跳或高踢腿，比静态拉伸更能让肌肉为接下来的运动做好准备。即使不用科学眼光来看，动态热身也更有趣。”