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Micah True, legendary ultra-marathoner, died suddenly while on aroutine 12-mile training run March 27, 2012. The mythic CaballoBlanco in the best-selling book, Born to Run, True would run as faras 100 miles in a day. On autopsy his heart was enlarged andscarred; he died of a lethal arrhythmia (irregularity of the heart rhythm). Although speculative, thepathologic changes in the heart of this 58 year-old veteran extremeendurance athlete may have been manifestations of "Phidippidescardiomyopathy," a condition caused by chronic excessive enduranceexercise. Regular exercise is highly effective for the prevention andtreatment of many common chronic diseases, and improvescardiovascular health and longevity. However, recent researchsuggests that chronic training for, and competing in, extremeendurance exercise such as marathons, iron man distance triathlons,and very long distance bicycle races may cause structural changesto the heart and large arteries, leading to myocardial injury. Astudy in the June issue of Mayo Clinic Proceedings reviews the literature and outlines in detail for the first timethe mechanisms, pathophysiology, and clinical manifestations ofcardiovascular injury from excessive endurance exercise. "Physical exercise, though not a drug, possesses many traits of apowerful pharmacologic agent. A routine of daily physical activitycan be highly effective for prevention and treatment of manydiseases, including coronary heart disease , hypertension , heart failure , and obesity ," says lead author James H. O'Keefe, MD, of Saint Luke's Hospitalof Kansas City, MO. "However, as with any pharmacologic agent, asafe upper dose limit potentially exists, beyond which the adverseeffects of physical exercise, such as musculoskeletal trauma andcardiovascular stress , may outweigh its benefits." Dr. O'Keefe and his colleagues present emerging data suggestingthat extreme endurance training can cause transient structuralcardiovascular changes and elevations of cardiac biomarkers, all ofwhich return to normal within one week. For some individuals, overmonths and years of repetitive injury, this process can lead to thedevelopment of patchy myocardial fibrosis, particularly in theatria, interventricular septum, and right ventricle, and anincreased susceptibility to atrial and ventricular arrhythmias. Inone study, approximately 12% of apparently healthy marathon runnersshowed evidence for patchy myocardial scarring, and the coronaryheart disease event rate during a two-year follow up wassignificantly higher in marathon runners than in controls. Although it has been recognized that elite-level athletes commonlydevelop abnormal electrocardiograms and atrial and ventricularentropy, these adaptations traditionally have not been thought topredispose to serious arrhythmias or sudden cardiac death. However,it now appears that the cardiac remodeling induced by excessiveexercise can lead to rhythm abnormalities. Endurance sports such asultramarathon running or professional cycling have been associatedwith as much as a 5-fold increase in the prevalence of atrial fibrillation . Chronic excessive sustained exercise may also be associated withcoronary artery calcification, diastolic dysfunction, andlarge-artery wall stiffening. Lifelong vigorous exercisers generally have low mortality anddisability rates and excellent functional capacity, Dr. O'Keefenotes. He suggests that further investigation is needed to identifywho is at risk for adverse cardiovascular remodeling, and toformulate physical fitness regimens for conferring optimalcardiovascular health and longevity. In a video interview accompanying the article, Dr. O'Keefe stressesthat the report does not detract from the importance of physicalexercise. "Physically active people are much healthier than theirsedentary counterparts. Exercise is one of the most importantthings you need to do on a daily basis," he explains. "But whatthis paper points out is that a lot of people do not understandthat the lion's share of health benefits accrue at a relativelymodest level. Extreme exercise is not really conducive to greatcardiovascular health. Beyond 30-60 minutes per day, you reach apoint of diminishing returns." Additional References Citations. We are high quality suppliers, our products such as China Solar Yard Lamp , Solar Lawn Lamps Manufacturer for oversee buyer. To know more, please visits Solar Lawn Lamps.
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