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?

有很多人都考虑在2016年参加马拉松比赛或其他长时间的耐力活动，然而，这样的雄心会不会造成运动过度？如此艰苦的锻炼会不会损伤我们的心脏？我们的配偶、其他家庭成员、当然还有我们自己不由产生了担忧。

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.

最新发表的一项科学综述让我们大为安心，但它同时也提出了一些警告。该研究发现，尽管大多数运动员的心脏都能承受大部分的运动，但也有例外。运动的沉重负荷可能为某些看似身体健康的人造成麻烦。正是出于这个原因，所有平日锻炼的人都应该尽可能详细地了解自己家族的心脏病史以及自己潜在的遗传风险。

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.

当然，一般而言，锻炼对心脏健康大有益处。数十项大型流行病学研究都发现，无论是每天锻炼5分钟还是2个小时，锻炼身体的人患心脏病或因心脏病死亡的风险要比久坐不动的人要低得多。

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.

但这些研究在给予我们鼓励的同时，也隐含着些令人不安的信息。根据数据绘制出的锻炼的心脏效益曲线往往呈钟形，这意味着，在某个点之前，锻炼得越多，人出现心脏问题的风险就越低，但越过这个点之后，锻炼的效益就会出现平台期或者有所下降。

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?

有些科学家直觉地认为这一发现说不通。既然少量锻炼有益于心脏，那为什么加大锻炼量却不会带来更大的好处呢？

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.

作为一名有多年经验的马拉松跑者，哈特福德医院（Hartford Hospital，位于康涅狄格州）的心脏科主任保罗·汤普森(Paul Thompson)博士对这一问题特别感兴趣。最近，他和他在哈特福德医院的同事们以及荷兰内梅亨大学医学中心(Radboud University Medical Center in Nijmegen)的科学家们决定一同对这一课题的现有数据进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.

以往有许多研究着眼于从个人角度来探讨长期锻炼与心脏健康。然而，却未曾有综述全面审查过长时间的耐力训练对心脏的效应，或总结这些研究是否提示我们应警惕高强度锻炼带来的影响。

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，在这项1月发表在《生理学评论》杂志(Physiological Reviews)上的新研究中，汤普森博士及其同事收集了他们能找到的过去30多年来与锻炼和心脏健康有关的所有研究，并个别和综合分析了这些研究的结果。

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

他们的研究结果应该可以让我们和我们那些忧心忡忡的亲人放下心来。

“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.

汤普森博士告诉我：“目前没有证据说明某种运动水平会给正常、健康的人带来危险或让人‘锻炼过度’。”

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，正如汤普森博士及其同事们在该综述中所写：平日锻炼的人也应该明白，频繁的运动训练确实会引起“心脏的生理和结构发生重大改变。”

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.

他们指出，短期看来，这些改变有点像心脏损伤，也就是说，在剧烈运动之后，心脏细胞往往会“漏”，将蛋白质释放入血液——换了别的情况，这可能预示着心肌梗死。不过，这些蛋白质通常几天内就会消失，心脏也完全“康复”了，汤普森博士说。

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.

但是在这个过程中，心脏出现了适应性改变：左、右心室扩大，从形态上开始与那些非运动员的心脏有了很大差异。

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.

这些变化对于大多数人来说都是有益的，对于取得优异的运动成绩也必不可少。不过，正如汤普森博士和他的同事所写的那样，他们在做完研究综述后发现，世事总有例外，有些人表面上健康，但剧烈运动却可能给他们带来意想不到的危险。

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.

也许最令人惊讶的是，研究表明，中老年马拉松选手与久坐不动的人一样容易患动脉粥样硬化（也就是危险斑块在动脉中堆积）。在因遗传或生活方式原因更容易患这种疾病的人当中，剧烈运动对斑块没有预防效果。

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，运动时的动作可能会增加斑块破裂的风险，引发心肌梗死。研究显示，与静坐时相比，动脉粥样硬化患者在跑步时更可能发生心肌梗死。

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

但是，很多患有动脉粥样硬化的中老年运动员对自己的病情一无所知，虽然有些症状已经出现。

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.

这项新综述还显示，某些遗传性心脏异常，如心肌病（心脏肥大）或长QT综合征（心脏电活动的紊乱）的患者在剧烈运动时，病情可能加剧。作者们在综述中写道，虽然心脏重构对大多数锻炼者有益，但对上述患者却有害，可能会导致他们过早死亡。一些研究发现剧烈运动的健康效益从统计学上偏低，可能有这方面的原因。

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.

不过，汤普森博士表示，对这些信息的最佳反应不是恐慌并避免剧烈运动，而是“了解自己家族的猝死病史”。如果你有近亲因为心脏问题而意外死亡，请与你的医生谈谈，看你是否需要接受测试，以检查有无动脉粥样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.

其他的人也应该注意在运动中是否出现了不寻常的疲劳、呼吸急促或胸痛等症状，汤普森博士说，但总的说来，锻炼更可能强健我们的心脏，而不是伤害它们。