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.
Regular exercise is highly effective for the prevention and treatment of many common chronic diseases, and improves cardiovascular health and longevity. However, recent research suggests that chronic training for, and competing in, extreme endurance exercise such as marathons, iron man distance triathlons, and very long distance bicycle races may cause structural changes to the heart and large arteries, leading to myocardial injury. A study in the June issue of Mayo Clinic Proceedings reviews the literature and outlines in detail for the first time the mechanisms, pathophysiology, and clinical manifestations of cardiovascular injury from excessive endurance exercise.
"Physical exercise, though not a drug, possesses many traits of a powerful pharmacologic agent. A routine of daily physical activity can be highly effective for prevention and treatment of many diseases, including coronary heart disease, hypertension, heart failure, and obesity," says lead author James H. O'Keefe, MD, of Saint Luke's Hospital of Kansas City, MO. "However, as with any pharmacologic agent, a safe upper dose limit potentially exists, beyond which the adverse effects of physical exercise, such as musculoskeletal trauma and cardiovascular stress, may outweigh its benefits."
Dr. O'Keefe and his colleagues present emerging data suggesting that extreme endurance training can cause transient structural cardiovascular changes and elevations of cardiac biomarkers, all of which return to normal within one week. For some individuals, over months and years of repetitive injury, this process can lead to the development of patchy myocardial fibrosis, particularly in the atria, interventricular septum, and right ventricle, and an increased susceptibility to atrial and ventricular arrhythmias. In one study, approximately 12% of apparently healthy marathon runners showed evidence for patchy myocardial scarring, and the coronary heart disease event rate during a two-year follow up was significantly higher in marathon runners than in controls.
Although it has been recognized that elite-level athletes commonly develop abnormal electrocardiograms and atrial and ventricular entropy, these adaptations traditionally have not been thought to predispose to serious arrhythmias or sudden cardiac death. However, it now appears that the cardiac remodeling induced by excessive exercise can lead to rhythm abnormalities. Endurance sports such as ultramarathon running or professional cycling have been associated with as much as a 5-fold increase in the prevalence of atrial fibrillation.
Chronic excessive sustained exercise may also be associated with coronary artery calcification, diastolic dysfunction, and large-artery wall stiffening.
Lifelong vigorous exercisers generally have low mortality and disability rates and excellent functional capacity, Dr. O'Keefe notes. He suggests that further investigation is needed to identify who is at risk for adverse cardiovascular remodeling, and to formulate physical fitness regimens for conferring optimal cardiovascular health and longevity.
In a video interview accompanying the article, Dr. O'Keefe stresses that the report does not detract from the importance of physical exercise. "Physically active people are much healthier than their sedentary counterparts. Exercise is one of the most important things you need to do on a daily basis," he explains. "But what this paper points out is that a lot of people do not understand that the lion's share of health benefits accrue at a relatively modest level. Extreme exercise is not really conducive to great cardiovascular health. Beyond 30-60 minutes per day, you reach a point of diminishing returns."
Eileen Leahy | EurekAlert!
Live probiotics can re-balance the gut microbiome and modify immune system response
20.11.2018 | Symprove
Purdue cancer identity technology makes it easier to find a tumor's 'address'
16.11.2018 | Purdue University
Max Planck researchers revel the nano-structure of molecular trains and the reason for smooth transport in cellular antennas.
Moving around, sensing the extracellular environment, and signaling to other cells are important for a cell to function properly. Responsible for those tasks...
Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.
Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...
Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.
Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...
Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.
In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...
On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.
19.11.2018 | Event News
09.11.2018 | Event News
06.11.2018 | Event News
20.11.2018 | Life Sciences
20.11.2018 | Life Sciences
20.11.2018 | Physics and Astronomy