May 21, 2015
Marathons: In the Long Run Not Heart Healthy
John C. Hagan III, MD & James H. O’Keefe, MD
As the June7, 2014 Hospital Hill Half-Marathon “run up” commences, disturbing research is accumulating about potential cardiovascular dangers of exercising at maximal levels for durations over an hour, especially after age 40. While this type of ‘excessive endurance exercise’ can occur with cross-country skiing, long distance swimming, triathlons, and 100+ mile bike races, the prototype activity is marathon running.
The first marathon occurred about 2500 years ago by the messenger Pheidippides who ran the 26.2 miles from the plains of Marathon to Sparta there proclaiming the Greek victory over the Persians. History records his first words were, “Joy to you, we’ve won.” Less certain are his last words, perhaps “My feet are killing me” before dropping dead.
Incredibly many physicians and the public have misinterpreted Pheidippides’ fatal run as healthful. In 2014 there are 739 marathons scheduled in the United States and Canada. It is estimated that over a half million people will complete a marathon this year. 100 mile ultra-marathons are common and worldwide months long extreme-endurance races of over 3000 miles exist.
Research published in the April 2014 Missouri Medicine: The Journal of the Missouri State Medical Association, a peer-reviewed medical journal, found that long-distance running over decades of life may cause a greater than normal buildup of calcified “hard” plaque and the more dangerous fatty “soft” plaques in the vital coronary arteries that supply the heart muscle. Lead authors Robert S. Schwartz, MD, of the Minneapolis Heart Institute, and James H. O'Keefe, MD, Saint Luke's Mid America Heart Institute, Kansas City found that long-term participation in marathon training and racing is paradoxically associated with increased coronary plaque volume. Since most marathon runners believe their long hours exercising, sometimes logging over a hundred miles per week for years on end, creates a strong healthy heart, or at least does not damage this vital organ, this new information is perplexing and shocking. Nevertheless, daily and less strenuous exercise remains one of the most important facets of getting and staying healthy.
Regular exercise and high levels of physical fitness are linked to lower risks for cardiovascular diseases and improved life expectancy. Four decades ago Thomas Bassler, MD, an American physician, reasoned that if some exercise was good more had to be better, and famously hypothesized that marathon running confers immunity against coronary plaque buildup and heart attacks. In the current study, Bassler’s theory—long term marathon running protects against coronary atherosclerosis—was tested by quantitatively assessing coronary artery plaque using high resolution coronary computed tomographic angiography (CCTA) in veteran male marathon runners.
To qualify for the study the long distance runners had to have completed at least one marathon each year for 25 consecutive years. The control subjects were a group of apparently healthy men who had never been regular vigorous exercisers but who were similar to the marathoners in age and other general cardiovascular risk factors. The 50 male marathon runners, as compared to the 23 inactive male controls, had increased total heart artery plaque volume, calcified plaque volume and non-calcified plaque volume. Although other medical studies had indicated that marathon running can cause accumulation of the less dangerous “hard” plaque this was the first time “soft” plaque was also found to be elevated. Soft plaque rupture and clot formation is felt to be the most common cause of heart attacks and sudden cardiac death.
Additionally, a Missouri Medicine editorial overview of excessive endurance exercise by prominent cardiologists Peter McCullough, MD, of the Baylor Medical Center, and Carl Lavie, MD, of the John Ochsner Heart and Vascular Institute, conclude that in marathon runners the chronic stress of endurance training for long periods of time may stiffen the heart arteries predisposing them to hardening and becoming partially blocked. Unlike other sports because the heart is pumping 5-8 times as much blood as during rest, marathon runners while training and racing hold this heavy strain on the heart for a very long time without rest breaks. When this happens, it may stretch the heart chambers and lead to scar formation in the cardiac muscle. Scar tissue in the heart is the cause of lethal heart arrhythmias and cardiac arrest in some of the highly publicized cases of seemingly healthy marathoners who die during training or long-distance running events. These deaths include 57 year old ultra-marathoner Micah True, also known as Caballo Blanco featured in the best-selling book Born to Run and 52 year old Jim Fixx author of The Complete Book of Running. Both died while running. Boston Marathon winner Alberto Salazar at age 47 was luckier and was successfully resuscitated after sustaining a heart attack while running, collapsing unconscious and without a pulse for 14 minutes.
Future research is needed to find who is susceptible to having this happen, why, and how can we best train and exercise and enjoy the benefits without taking on life-threatening risks. One such test is a Heart CT Scan. This relatively quick and painless examination can measure calcium deposits in the heart arteries. These calcium deposits are indicative of plaques in the coronary arteries. A normal value is zero but numbers over a 100 are associated with increasing risks of heart disease including angina, heart attacks and cardiac death. St. Luke’s Hospital offers Heart CT tests for $50 which is usually not covered by insurance. Tests can be scheduled by calling XXXXXX. No physician referral is required.
Exercise might be best understood as a drug with powerful benefits, especially for cardiovascular health. As with any potent drug, establishing the safe and effective dose range is critically important—an inadequately low dose may not confer full benefits, whereas an excessive dose might produce harmful effects that outweigh its benefits. Running marathons for decades is an excessive amount of exercise, predisposing to an increased coronary artery plaque buildup despite favorably altering many risk factors such as weight, blood pressure and risk of diabetes. A more moderate dose of exercise is a better strategy for promoting long-term cardiovascular health and durability.
An example of a sensible and time efficient ‘exercise prescription’ is shown in figure 1. Before starting or increasing exercise programs have a physical examination and discuss your exercise prescription with your personal physician.
Nothing in this new research invalidates that the most important and under-utilized “wonder drugs” for health maintenance are regular moderate exercise, a good diet, body weight vigilance, avoidance of all nicotine use, for those that drink alcohol no more than 2 drinks per day-ideally red wine, drive carefully and always fasten the seatbelt, get plenty of sleep, develop a social network of friends, have a pet─preferably a dog to walk─ and a satisfying spiritual-religious belief system.
LINK TO SCIENTIFIC PAPERS:
About the authors:
John C. Hagan III, MD is the Editor of Missouri Medicine and a Discover Vision Centers-Northland ophthalmologist. He is a former marathon runner and current daily walker-swimmer.
James H. O’Keefe, MD is a nationally known preventive cardiologist with the Mid-America Heart Institute at St. Luke’s Hospital, Kansas City. He is a daily moderate exercising runner. He and his dietician wife Joan authored “Let Me Tell You a Story: Inspirational Stories for Health, Happiness and a Sexy Waist” (McNeel Publishing, 2013)