Over the last few months, during the endurance-athletics offseason, something extraordinary happened: The line began to blur between the health effects of running marathons and eating cheeseburgers.
'I'm not worried, ' says veteran running coach Mark Sullivan, who has run more than 150 marathons, joking that 'there are guys who live to be 100 smoking cigarettes and eating cheeseburgers.'
Endurance athletes have long enjoyed a made-of-iron image. But amid mounting evidence that extraordinary doses of exercise may diminish the benefits of modest amounts, that image is being smudged. That extra six years of longevity running has been shown to confer? That benefit may disappear beyond 30 miles of running a week, suggests recent research.
The improved blood pressure, cholesterol levels and robust cardiac health that exercise has been proven to bestow? Among extreme exercisers, those blessings may be offset partially by an increased vulnerability to atrial fibrillation and coronary-artery plaque, suggests other recent studies.
In the face of this research, long-standing skepticism about the possibility of 'exercise overdose' is softening among many sports physicians. 'The lesson I've learned from 40 years of cardiology is that when there's this much smoke, there's often some fire, ' said Paul Thompson, a sports-medicine specialist and veteran marathoner who is chief of cardiology at Hartford Hospital in Connecticut.
许多体育运动医学家一直都对存在“运动过量”这种可能性的说法表示质疑，但面对上述研究，他们中的很多人态度都在软化。康涅狄格州哈特福德医院(Hartford Hospital)心脏病学负责人、运动医学专家及马拉松老将保罗??汤普森(Paul Thompson)说：“四十年的心脏病学职业生涯教给我一点：无中不能生有，事出总是有因。”
Anecdotal concerns about endurance athletics have been building for years. Cardiac conditions that required surgery have forced into retirement two winners of the Ironman Triathlon World Championship. In 2011, Ironman winner Normann Stadler underwent emergency surgery to repair an enormous aortic aneurysm, a condition not caused but very possibly aggravated by endurance athletics. Research shows an association between endurance athletics and enlarged aortic roots.
坊间关于耐力运动的担忧由来已久。铁人三项世界锦标赛(Ironman Triathlon World Championship)的两位冠军得主就因为心脏病需要动手术而被迫退役。2011年，该赛事冠军得主诺曼??施泰德(Normann Stadler)就接受了一场治疗主动脉巨瘤的急诊手术。这种病虽然不是由耐力运动造成的，但后者很可能会加剧病情。研究表明，耐力运动和主动脉根部扩张二者之间存在着某种关联。
Other recent studies suggest the significant mortality benefits of running may diminish or disappear at mileage exceeding 30 miles a week and other, very small studies have shown elevated levels of coronary plaque in serial marathoners─a problem that rigorous exercise theoretically could cause.
'Heart disease comes from inflammation and if you're constantly, chronically inflaming yourself, never letting your body heal, why wouldn't there be a relationship between over exercise and heart disease?' said John Mandrola, a cardiac electrophysiologist and columnist for TheHeart.org.
Yet sports-medicine specialists are sharply divided over whether any warning is warranted. For every American who exercises to extremes, after all, there are thousands who don't exercise at all─and who might embrace any exercise-related warnings as cause for staying sedentary. Moreover, the evidence for extreme-exercise hazards is far from conclusive─and is contradicted by other studies suggesting the health benefits of exercise may accrue to infinity.
'It's true that the majority of cardiovascular protection comes from exercise at more moderate levels, but there is compelling evidence that there's no upper limit, ' said Benjamin Levine, director of the Institute for Exercise and Environmental Medicine in Dallas and professor of medicine at the University of Texas Southwestern Medical Center.
达拉斯运动和环境医学研究所(Institute for Exercise and Environmental Medicine)负责人、得克萨斯大学西南医学中心(University of Texas Southwestern Medical Center)医学教授本杰明??莱文(Benjamin Levine)说：“有一点是确凿可信的，那就是大多对心血管的保护源自更适度的锻炼。但也有令人信服的证据表明，锻炼并没有上限。”
'I don't want anyone to read that exercise can be bad for you. added Mandrola, a passionate cyclist. 'Some folks do tons of exercise and are protected. Some folks probably have some individual susceptibility to it. I'm a big believer in short intervals of high intensity.'
Sports medicine has a history of ignoring warning signs. Long after evidence emerged that over-hydrating could prove fatal to marathoners, experts continued encouraging runners to drink as much as possible─leading to utterly preventable tragedies such as the death of a 43-year-old mother of three in the 1998 Chicago Marathon. 'Why did it take 20 years before the original evidence was accepted?' asked a 2006 article in the British Journal of Sports Medicine.
运动医学界有着对警告信号熟视无睹的历史。有证据表明，补水过度可能会对马拉松选手造成致命伤害。这一发现提出很久以后，专家们还是继续鼓励跑步者尽可能多地喝水──这就导致了一些原本完全可以避免的悲剧的上演，比如1998年在芝加哥马拉松赛(Chicago Marathon)中丧生的那位选手，她当时43岁，是三个孩子的母亲。2006年，《英国运动医学杂志》(British Journal of Sports Medicine)发表的一篇文章提出了这样一个问题：“为什么这个原始证据在二十年之后才被人接受？”
Following the recent emergence of studies finding high levels of coronary plaque in marathon runners, sports medicine is debunking the myth that distance running confers near-absolute protection against heart disease. 'The thinking used to be, if you're a marathoner, you're protected, ' said Thompson. While taking seriously the growing evidence for potential risks of endurance exercise, Thompson said he isn't advising his patients against it. 'As a former marathoner, I have a sympathetic bent toward large amounts of exercise.'
Publicizing the potential dangers of endurance exercise could give recreational athletes an argument for resisting pressure to go longer and harder. Within the running and triathlon communities, glory is often reserved for those who go extreme distances. 'The longer you go, the more attention people pay to you, ' said Aaron Baggish, a triathlete, marathoner and Massachusetts General Hospital cardiologist.
向公众宣传耐力运动的潜在危险可能会给业余运动员一个浅尝辄止的理由，在面临需要他们跑得更远、付出更多努力的压力时会产生抗拒。在跑步和铁人三项的圈子里，荣誉总是留给那些愿意挑战里程极限的人。波士顿麻省总医院(Massachusetts General Hospital)心脏病专家、铁人三项和马拉松选手亚伦??巴吉胥(Aaron Baggish)说：“你跑得的路越长，得到的关注也就越多。”
The loudest voice warning about the dangers of endurance exercise may be that of James O'Keefe, a sports cardiologist and former elite triathlete. In his late forties, O'Keefe started experiencing heart palpitations following heavy workouts. He now believes the culprit was unrelenting exercise. An article he co-wrote last year in the Mayo Clinic Proceedings said: 'Long-term excessive endurance exercise may induce pathological structural remodeling of the heart and large arteries.'
在关于耐力运动有危险的警告声中，最响亮的声音可能来自詹姆斯??欧基夫(James O'Keefe)。身为运动心脏病专家的欧基夫曾是一名铁人三项精英赛选手，但临近50岁时，欧基夫在进行高强度锻炼后开始出现心悸。他现在认为无休止的运动是这一切的罪魁祸首。去年，《梅奥诊所学报》(Mayo Clinic Proceedings)发表了欧基夫与他人合着的一篇文章，其中写道：“长期过度的耐力运动可能会诱发心脏和大动脉产生病理结构性重建。”
As director of a decades-long project called the National Runners' Health Study, Paul Williams has published dozens of scientific articles showing that running─the more the better─confers a variety of robust health benefits. But along with Hartford's Thompson, Williams just completed a study of 2, 377 runners and walkers who had survived heart attacks. Over 10.4 years, 526 of them died, 71.5% of them from cardiovascular disease. What Williams found is that the more they ran or walked after a heart attack, the less likely they were to die of heart disease─until they exceeded 7.1 kilometers of running or 10.7 kilometers of walking daily.
全美跑步者健康研究(National Runners' Health Study)是一个持续了数十年的项目，该项目负责人保罗??威廉姆斯(Paul Williams)已发表了几十篇科学论文，文章均表明跑步──越多越好──给人的健康带来了种种好处。但威廉姆斯也与哈特福德医院的汤普森一起完成了针对2,377名在心脏病后存活了下来的跑步者和步行者的一项研究。在10.4年的时间里，共有526名参与者去世，其中71.5%的人死于心血管疾病。威廉姆斯发现，他们在心脏病发后跑得越多或走得越多，其死于心脏病的风险就越小，前提是他们的运动里程不能超过临界点──一天跑步超过7.1公里或走路超过10.7公里。