運動過度真的會損害心臟健康

With many of us contemplating marathons or other prolonged endurance events in 2016, we, our spouses and other family members most likely have wondered whether such strenuous training could be harmful to our hearts. Could any of us, in making ambitious resolutions, exercise too much?

有很多人都考慮在2016年參加馬拉松比賽或其他長時間的耐力活動，然而，這樣的雄心會不會造成運動過度？如此艱苦的鍛鍊會不會損傷我們的心臟？我們的配偶、其他家庭成員、當然還有我們自己不由產生了擔憂。

A newly published scientific review offers both reassurance and some caution. It found that while most athletes’ hearts can withstand most exercise, there are exceptions. For some people in seemingly good health, heavy loads of exercise might be problematic. That’s why all of us who work out should be as informed as possible about our family’s cardiac history and our own potential genetic risks.

最新發表的一項科學綜述讓我們大爲安心，但它同時也提出了一些警告。該研究發現，儘管大多數運動員的心臟都能承受大部分的運動，但也有例外。運動的沉重負荷可能爲某些看似身體健康的人造成麻煩。正是出於這個原因，所有平日鍛鍊的人都應該儘可能詳細地瞭解自己家族的心臟病史以及自己潛在的遺傳風險。

Exercise, of course, is in general extremely beneficial for heart health. Dozens of large-scale epidemiological studies have found that people who exercise in any amount, whether five minutes a day or two hours a day or more, are much less likely to develop or die from heart disease than people who are sedentary.

當然，一般而言，鍛鍊對心臟健康大有益處。數十項大型流行病學研究都發現，無論是每天鍛鍊5分鐘還是2個小時，鍛鍊身體的人患心臟病或因心臟病死亡的風險要比久坐不動的人要低得多。

But these studies, while encouraging, contain a disquieting subtext. Their plotted data typically shows some type of bell curve to the heart benefits from exercise, meaning that the more people work out, the less they are at risk of cardiac problems — up to a point, and then the benefits plateau or decline.

但這些研究在給予我們鼓勵的同時，也隱含着些令人不安的信息。根據數據繪製出的鍛鍊的心臟效益曲線往往呈鐘形，這意味着，在某個點之前，鍛鍊得越多，人出現心臟問題的風險就越低，但越過這個點之後，鍛鍊的效益就會出現平臺期或者有所下降。

To some scientists, that finding made little intuitive sense. If a little exercise is good for the heart, why shouldn’t more be continually better?

有些科學家直覺地認爲這一發現說不通。既然少量鍛鍊有益於心臟，那爲什麼加大鍛鍊量卻不會帶來更大的好處呢？

Dr. Paul Thompson, the chief of cardiology at Hartford Hospital in Connecticut and for years a dedicated marathon runner, was particularly drawn to that issue. He and his colleagues at Hartford Hospital, along with scientists at the Radboud University Medical Center in Nijmegen, the Netherlands, recently decided to delve more comprehensively than had yet been done into the available data on the topic.

作爲一名有多年經驗的馬拉松跑者，哈特福德醫院（Hartford Hospital，位於康涅狄格州）的心臟科主任保羅·湯普森(Paul Thompson)博士對這一問題特別感興趣。最近，他和他在哈特福德醫院的同事們以及荷蘭內梅亨大學醫學中心(Radboud University Medical Center in Nijmegen)的科學家們決定一同對這一課題的現有數據進行更深入全面地研究。

Many past studies have looked at individual aspects of prolonged exercise and heart health. But no past review had comprehensively examined all of the ways in which prolonged endurance exercise might affect the heart and whether, on aggregate, those studies indicated that we should — or should not — worry about the effects of heavy training.

以往有許多研究着眼於從個人角度來探討長期鍛鍊與心臟健康。然而，卻未曾有綜述全面審查過長時間的耐力訓練對心臟的效應，或總結這些研究是否提示我們應警惕高強度鍛鍊帶來的影響。

So for the new study, being published next month in Physiological Reviews, Dr. Thompson and his collaborators gathered all of the studies they could find from the past 30 or more years related to exercise and heart health, and parsed their findings both singly and collectively.

因此，在這項1月發表在《生理學評論》雜誌(Physiological Reviews)上的新研究中，湯普森博士及其同事收集了他們能找到的過去30多年來與鍛鍊和心臟健康有關的所有研究，並個別和綜合分析了這些研究的結果。

Their findings should reassure most of us and our concerned loved ones.

他們的研究結果應該可以讓我們和我們那些憂心忡忡的親人放下心來。

“There is no evidence that there is a level of exercise that is dangerous or too much for a normal, healthy person,” Dr. Thompson told me.

湯普森博士告訴我：“目前沒有證據說明某種運動水平會給正常、健康的人帶來危險或讓人‘鍛鍊過度’。”

At the same time, those of us who work out should understand that frequent exercise training causes “profound changes in cardiac physiology and structure,” as Dr. Thompson and his colleagues write in their review.

另一方面，正如湯普森博士及其同事們在該綜述中所寫：平日鍛鍊的人也應該明白，頻繁的運動訓練確實會引起“心臟的生理和結構發生重大改變。”

In the short term, these changes can mimic heart damage, they point out, with cardiac cells often becoming “leaky” after strenuous workouts or events, releasing proteins into the bloodstream that, in other circumstances, could indicate a heart attack. These proteins usually disappear within a few days, and the heart seems to recover fully, Dr. Thompson said.

他們指出，短期看來，這些改變有點像心臟損傷，也就是說，在劇烈運動之後，心臟細胞往往會“漏”，將蛋白質釋放入血液——換了別的情況，這可能預示着心肌梗死。不過，這些蛋白質通常幾天內就會消失，心臟也完全“康復”了，湯普森博士說。

But in the process, the heart adapts and changes. Its left and right ventricles enlarge. It begins to look quite different than a non-athlete’s heart.

但是在這個過程中，心臟出現了適應性改變：左、右心室擴大，從形態上開始與那些非運動員的心臟有了很大差異。

For most people, these changes are beneficial and also necessary for successful athletic performance. But, as Dr. Thompson and his colleagues write, their review of the studies indicates that there are outliers, seemingly healthy people for whom strenuous exercise holds unexpected dangers.

這些變化對於大多數人來說都是有益的，對於取得優異的運動成績也必不可少。不過，正如湯普森博士和他的同事所寫的那樣，他們在做完研究綜述後發現，世事總有例外，有些人表面上健康，但劇烈運動卻可能給他們帶來意想不到的危險。

Perhaps most surprising, older marathon runners can be just as susceptible as their sedentary counterparts to atherosclerosis, or the buildup of dangerous plaques in the arteries, the studies show. Strenuous exercise does not prevent these plaques in people who are predisposed by heredity or lifestyle to the condition.

也許最令人驚訝的是，研究表明，中老年馬拉松選手與久坐不動的人一樣容易患動脈粥樣硬化（也就是危險斑塊在動脈中堆積）。在因遺傳或生活方式原因更容易患這種疾病的人當中，劇烈運動對斑塊沒有預防效果。

The act of exercising, however, may increase the risk that the plaques will rupture, precipitating a heart attack. Someone with atherosclerosis is more likely, studies show, to have a heart attack while running than while sitting quietly.

而且，運動時的動作可能會增加斑塊破裂的風險，引發心肌梗死。研究顯示，與靜坐時相比，動脈粥樣硬化患者在跑步時更可能發生心肌梗死。

But many older athletes with atherosclerosis have no idea they suffer from the condition, which often causes few symptoms.

但是，很多患有動脈粥樣硬化的中老年運動員對自己的病情一無所知，雖然有些症狀已經出現。

Similarly, according to the new review, people with certain inherited heart abnormalities, such as cardiomyopathy (an enlarged heart) or long QT syndrome, a disorder of the heart’s electrical activity, may exacerbate their conditions with strenuous exercise. The cardiac remodeling that is beneficial for most exercisers, the reviewers write, is undesirable for them and could lead to premature death, possibly contributing to the statistical downturn in health benefits from extreme exercise seen in some studies.

這項新綜述還顯示，某些遺傳性心臟異常，如心肌病（心臟肥大）或長QT綜合徵（心臟電活動的紊亂）的患者在劇烈運動時，病情可能加劇。作者們在綜述中寫道，雖然心臟重構對大多數鍛鍊者有益，但對上述患者卻有害，可能會導致他們過早死亡。一些研究發現劇烈運動的健康效益從統計學上偏低，可能有這方面的原因。

The best response to this information is not, however, to panic and avoid strenuous exercise, Dr. Thompson said. The best response is “to know your family history of sudden death,” he said. If a close family member has died unexpectedly of heart problems, talk to your doctor about whether you need to be tested for conditions such as atherosclerosis or cardiomyopathy.

不過，湯普森博士表示，對這些信息的最佳反應不是恐慌並避免劇烈運動，而是“瞭解自己家族的猝死病史”。如果你有近親因爲心臟問題而意外死亡，請與你的醫生談談，看你是否需要接受測試，以檢查有無動脈粥樣硬化或心肌病等疾病。

The rest of us should pay attention to symptoms such as unusual fatigue, shortness of breath or chest pain during exercise, he said, but are much more likely to strengthen our hearts with exercise than harm them.

其他的人也應該注意在運動中是否出現了不尋常的疲勞、呼吸急促或胸痛等症狀，湯普森博士說，但總的說來，鍛鍊更可能強健我們的心臟，而不是傷害它們。