The Exercise Equivalent of a Cheeseburger? - WSJ.com
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.
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.
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."
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 40s, 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."
As director of a decadeslong 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.
For its subjects, the study concludes, "Excessive exercise significantly increases mortality."
MARATHON RUNNERS HAVE CALCIFIED ARTERIES! : Dr. Pinna
Metabolic and Mechanical Stress
In this study, the father-and-son team, both runners, wanted to assess coronary artery plaque in an elite group of marathon runners and compare their arteries with a control group. They identified 25 runners who completed the Minneapolis-St Paul Twin Cities Marathon every year for 25 consecutive years, thus completing a minimum of 25 marathons.
All subjects underwent coronary computed tomography angiography (CTA) using a 64-slice machine. Compared with controls, marathoners had significantly more calcified plaque volume–274 mm3 for the marathoners and 169 mm3 for the controls–and higher calcium scores and noncalcified plaque volumes, although the latter two measures did not reach statistical significance.
Robert Schwartz told heartwire that patient age, systolic blood pressure, total cholesterol, LDL cholesterol, and triglyceride levels were similar between the marathoners and controls, but heart rate, weight, and body-mass index were lower in the runners. Also, HDL-cholesterol levels were significantly higher in the runners than in the controls. The average total- and LDL-cholesterol levels were 190 mg/dL and 115 mg/dL, respectively, in the marathon runners, which suggests that diet is not is the reason for the increased calcification.
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Asked about the possible mechanisms, Jonathan Schwartz said they don’t know why the runners had more plaque in the arteries than the controls and that the findings are “counterintuitive.” However, he pointed out that metabolic and mechanical stresses might be a contributing factor. For example, long-distance runners train at increased heart rates and blood pressures, as well as spend increased time in an anaerobic state, possibly leading to antioxidant damage. Also, damage to the bones might lead to calcium leaking into the bloodstream. They stressed, however, such possible explanations need to be explored further.
Another study, also presented during the ACC meeting, suggested that marathon runners had increased aortic stiffness compared with individuals who exercised recreationally. The researchers, led by Dr Despina Kardara (Athens Medical School, Greece), evaluated blood pressure and aortic elasticity in 42 males and seven females who trained for and ran marathons and 46 men who did not participate in endurance exercise training. On average, the runners trained between two to nine hours per week and had been doing so for periods of 30 months to 21 years.
The marathon runners had significantly higher systolic blood pressure compared with the control group (126 mm Hg vs 115 mm Hg) and higher diastolic blood pressures. Pulse-wave velocity, used to assess aortic stiffness, was significantly higher in the marathon group.
Competing risks of mortality with marathons: retrospective analysis | BMJ
The final 1.6 km of the marathon represents less than 5% of the total distance yet accounts for almost 50% of the sudden cardiac deaths.
Excessive endurance training can be too much of a good thing, research suggests
Micah True, legendary ultra-marathoner, died suddenly while on a routine 12-mile training run March 27, 2012. The mythic Caballo Blanco in the best-selling book, Born to Run, True would run as far as 100 miles in a day. On autopsy his heart was enlarged and scarred; he died of a lethal arrhythmia (irregularity of the heart rhythm). Although speculative, the pathologic changes in the heart of this 58 year-old veteran extreme endurance athlete may have been manifestations of "Phidippides cardiomyopathy," a condition caused by chronic excessive endurance exercise.
http://naturalrunningcenter.com/2012/05/10/autopsy-report-micah-trues-death-due-cardiomyopathy/
Micah True Autopsy Report
The pathologist found the only abnormality was True’s heart was dilated. In particular his left ventricle was mildly dilated and thickened. There was no evidence of blockage or significant narrowing in any of the coronary arteries; he did not have a heart attack. There was no evidence of trauma such as a fall causing his death.
The coroner concluded it is likely True suffered an exercise -induced cardiac arrhythmia that caused his death. The abnormal rhythm it was concluded occurred due to the structural changes found of his left ventricle.
It is unclear if continued and repeated ultramarathon running caused the changes found in True’s ventricle and led to his death, though it is a distinct possibility.
http://extremelongevity.net/wp-content/uploads/2401-12AutRpt.pdf
