健康生活:運動前不宜拉伸大綱
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.
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.
不過，所有關注運動科學（或本專欄）的人都知道，近年來有不少實驗都證明，運動前拉伸並不高明。研究者發現，所謂的靜態拉伸會讓跳高運動員跳得更低、短跑者跑得更慢；而且還不能顯著降低運動受傷的風險。Now, two new studies are giving us additional reasons not to stretch.
現在，又有兩個新研究爲我們提供了“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.
其中一項發表在本月的《力量與訓練研究雜誌》(The Journal of Strength and Conditioning Research)上。研究稱：假如你在舉重前進行拉伸運動，你會感覺舉的時候比預期力氣更小、踉踉蹌蹌。此結果與另一項由克羅地亞科學家對以往實驗進行的廣泛深入的再次分析不謀而合，該項研究發表於《北歐醫學與運動科學雜誌》(The Scandinavian Journal of Medicine and Science in Sports)。這兩項研究鞏固了一個日益強大的科學共識：通常情況下，在鍛鍊前做拉伸不僅沒必要，還可能起反作用。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.
鍛鍊與拉伸之間的很多關聯尚不明朗。特別是：人們不知道準確來說，拉伸到什麼程度會使接下來的鍛鍊受到影響；也不知道是否鍛鍊前拉伸對一切體育活動都產生相似作用。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.
爲了讓新研究涉及範圍更廣，同時解釋上述問題，克羅地亞薩格勒布大學(University of Zagreb)的科學家梳理了上百個以前進行過的實驗。這些實驗中，志願者先做拉伸運動，然後或跳、或扣籃、或舉重或進行肌肉強度與力量測試。基於研究目的，他們只選擇用靜態拉伸作爲唯一熱身運動的實驗；剔除了那些讓志願者在鍛鍊前除拉伸外還慢跑過或做過其他動態熱身的實驗。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.
最後，符合他們選擇標準的共有104項研究。他們綜合這些研究的結果，利用複雜的統計計算方法確定拉伸對鍛鍊的影響程度。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.
統計數字——尤其是對於競技型運動員的數字——發人深省。計算結果是：靜態拉伸讓拉伸後的肌肉強度下降約5.5%；進行過90秒以上拉伸活動的人下降程度更大；若短於45秒，則影響減輕。總體而言，拉伸過的肌肉強度普遍減弱。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.
同時，肌肉的力量也會變差。該研究的通訊作者、薩格勒布大學運動學教授葛蘭·馬爾科維奇(Goran Markovic)將肌肉力量解釋爲肌肉收縮時產生力量的能力。他與同事對過去實驗的再分析得出結論：拉伸後，肌肉力量降低約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.
還有一個結果是：肌肉的爆發力亦顯著降低——最高可達2.8%。也就是說，想從起跑線上立即起跑、將網球猛擊出去、挺舉槓鈴、籃下蓋帽、飛奔過馬拉松第一程的人，都被拉伸“坑苦了”。他們以拉伸運動來熱身比完全不熱身表現得差。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.
另一項新研究得到了類似結論。實驗中，年輕健壯的男性志願者被要求拉伸或不拉伸後做標準蹲舉槓鈴的動作。拉伸後，志願者能舉起的槓鈴重量比不拉伸時輕8.3%。更有意思的是，志願者們表示，他們覺得拉伸後比不拉伸時重心更不穩、身體更不平衡。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.
爲什麼拉伸會影響運動能力，這兩項新研究的作者還不清楚，儘管他們懷疑部分原因是拉伸的確起到了我們所期望的效果：讓肌肉與肌腱鬆弛。然而，拉伸也讓肌肉儲存能量和做爆發性動作的能力變差，就好比舊短褲上的鬆緊帶一樣——我敢肯定它害得我之前的跑步比賽用時過長，因爲我要提着褲子賽跑。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.
馬爾科維奇教授說：當然，新研究的結果主要適用於那些參加需要肌肉有強度和爆發力的比賽、而非耐力比賽的人們。不過有些研究也支持靜態拉伸不利於長跑和遠距離自行車運動的說法。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.
從根本上講，研究結果強調了不要在鍛鍊前進行拉伸類準備活動的重要性。馬爾科維奇教授說：“我們可以確切地說：僅僅做拉伸運動並不是熱身的好辦法。熱身運動應該提高運動能力。”他指出，熱身不應當使運動表現變糟。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.
他繼續講道：“動態熱身才是更好的選擇。事先活動一下即將利用到的肌肉。比如開並腿跳或高踢腿，比靜態拉伸更能讓肌肉爲接下來的運動做好準備。即使不用科學眼光來看，動態熱身也更有趣。”
