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Can Excessive Endurance Exercise Damage Your Heart?

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Pheidippides’ Last Message: “My Feet Are Killing Me!”

By John C. Hagan III, MD (Former Marathon Runner)

My fellow runners, I write this with a “heavy” heart.

Let me “run” something by you. Whoa, I forgot, that was the old marathoner-100 mile bicyclist-Half-Ironman Triathlon® me talking. Let the new easy exercising me “walk” you through this. A sea change is occurring in the understanding of heart disease and extreme endurance exercise. A growing number of influential cardiologists, including Missouri Medicine’s Preventive Medicine Editorial Board member James H. O’Keefe MD and his collaborators report persuasive evidence that prolonged (> one hour) maximal or near maximal aerobic exercise, especially after age 50, may be damaging to the myocardium and coronary arteries. Part of this body of evidence is the finding that veteran (a code word for “older”) marathoners and other endurance athletes have higher than normal coronary artery calcium scores (CACS) and rates of atrial fibrillation. Been there; got that!

I have been a long distance runner since about 1967. If I didn’t run at least 12 miles I felt it was a wasted effort. I was especially influenced by Kenneth Cooper MD and his book “Aerobics” and the pioneering work of Scottish physician Jeremiah N. Morris, MD who established the inverse relationship between mild to moderate physical activity with cardiovascular disease and American preventive cardiologist Jeremiah Stamler, MD who first coined the term “risk factors” for the association of hypertension, obesity, lack of exercise and lipid abnormalities with heart disease.

Running Pied Pipers appeared. Among them was pathologist Thomas Bassler, MD who in 1977 stated that running long distances prevented coronary artery disease and that no marathoner had died of a myocardial infarct in a 10 year study he conducted. This was first disproven by Timothy Noakes, MD who presented four marathoners that had died of autopsy proven coronary artery disease. Popular running author Jim Fixx, in 1984 at age 52, died of a heart attack while running; Olympic marathoner and 3 time winner of the New York Marathon Alberto Salazar, 47, was technically dead for 14 minutes due to a heart attack before being revived. He was found to have extensive coronary artery disease. (Note to self: pay attention to things like that next time).

Nevertheless the number of distance runners has swelled and races are longer and longer: 10 Kilometer, half-marathons, marathons (26.2 miles), 100 milers (including the Leadville, Colorado 100 that is run at altitudes between 9,200 feet and 12,600 feet) and the world’s current longest certified foot race the Self-Transcendence 3100 Miler. It requires that runners complete the distance within 51 days or an average of 60.68 miles/day.

My first published paper (1974) in Resident and Staff Physician “Survival of the Fittest” was about using exercise to reduce the risk of heart disease. Subsequently I bought into the ‘running more miles means better cardio-vascular health’ movement. Thinking I was giving my heart just what it needed to prevent disease, I ran more than 25 Hospital Hill Half Marathons, 4 marathons and two Half Ironman Triathlons (Figure 1). For many years I weekly averaged about 30-40 miles of running.

Figure 1. Thinking I was giving my heart just what it needed to prevent disease, I ran more than 25 Hospital Hill Half Marathons, 4 marathons and two Half Ironman Triathlons.

Ken Cooper MD, to his great credit, in 1985, was among the first to express concerns about running very long distances at all out effort. Cooper said that anyone running over 15 miles per week was pursuing something “other than fitness.” He also expressed concerns that long distances at maximum effort might suppress the immune system and predispose to neoplastic disease. Several very prominent long distance runners, such as New York City Marathon director Fred Lebow and Olympic Marathon Champion Greta Waitz died relatively young of cancer. Cooper also felt that most, if not all, of the benefits of aerobic exercise can be obtained from much shorter exercise periods and at less than “all out” intensity. Bingo! Please re-read that last sentence, it will be the new paradigm.

At age 61, my heart served notice of overuse and abuse when I developed atrial fibrillation as described in a previous editorial (Fascinating Rhythm: Atrial Fibrillation—The Beat Goes On. Missouri Medicine 2006;103: 200-201). So called “lone” atrial fibrillation is more common in endurance athletes such as marathoners, long distance cyclists and cross country skiers.

I am a charter subscriber (1966) to Runner’s World, the publication for runners. In the last 10 years it seems there have been more stories of marathoners and longer distance racers having heart attacks and/or death while running. There have been articles and letters in Runner’s World recommending that runners determine their Coronary Artery Calcium Score. Coronary artery calcium is a presumed proxy for atheroma and the higher the number (The Agatston Scale is used: a perfect score is zero; 100 or less is mild calcification) the greater the heart artery plaque burden is felt to be. In large random populations this translates into higher rates of cardiac events (cardiac death, clinical arrhythmias, angina or myocardial infarcts). A father/son team of running cardiologists from Minnesota found marathoners had higher CACS than age matched non-runners. Europeans researchers confirmed this finding. CACS can be determined by a quick, easy and inexpensive test called a Heart CT. It is an ongoing controversy among cardiologists and public health officials when this test should be obtained. It seems running up the score is unsportsmanlike conduct.

I had asked my former cardiologists about having a Heart CT and mentioned a disturbingly large number of marathoners reporting personal high CACS. More than a few with high CACS had work ups revealing coronary artery disease so severe that angioplasties, stents and even coronary artery by-pass grafts were needed. I was told the Heart CT would not tell those cardiologists anything they didn’t already know or change how I was treated. Being basically a compliant patient, I demurred.

By pure serendipity my ophthalmology practice changed health insurance plans and I had to find another cardiology group. When I again broached the Heart CT question, my new cardiologist told me I could have the test done as a walk in any day it was convenient for $50. I soon took the test with almost a smug expectation of zero coronary calcium. The results left me ‘broken hearted’. A nurse clinician gave me the disturbing news immediately after the test that my Agatston Score was 1606. OMG, the proverbial heart of stone. I have more calcium in my heart arteries than most people have in their long bones. The cardiologist was sufficiently alarmed that he called me at home and asked me to come to his office immediately.

Another intensive round of heart tests were normal. However this time rigorous interventions were done: I went to lipid clinic and changed a good diet into a fabulous diet. I went from a somewhat over-weight 192 pounds (BMI = 25.3) to a svelte 177 (BMI 23.3). My cholesterol was satisfactory but triglycerides borderline high. I went on statins. My lipid profile is so exemplary I now take low dose statins every other day. My blood pressure medications were tweaked to superb levels and, with the weight loss, gradually cut back also. For the record, I am a lifetime non-smoker.

My new heart friendly exercise program (5-6 days/week walking, swimming, bicycling, weight lifting) is never done at maximum effort and, except for moderate speed walking (with 2 minute stand-still recovery breaks), is less than an hours duration. I’ve updated my estate planning; I take time to smell the roses every day; I’m hoping, as Agastston himself suggests, that my coronary artery plaques have been stabilized with intact lumen and any soft, lipid filled thrombosis-causing plaque eliminated.

So what’s the message here? Physicians, including me, have the medicine (exercise) correct but we definitely have got the dosageâfaster and furtherâ wrong. This happens all the time. Let me give you an example from the marathon world. In the mid 1960’s most marathon race day deaths were from heat stroke brought on by inadequate hydration. The sustained message to runners was to drink as much water as possible during the run. In recent marathons the majority of deaths have been from drinking too much water leading to fatal dilutional hyponatremia. Exercise is the same: too little can kill you, too much can kill you. Regular, moderate exercise is as close to a magic elixir-fountain of youth as we are likely to discover.

I understand statistics, I understand the tyranny of small numbers and under-powered studies; here N = 1 and one is the loneliest number. Thus qualified, I believe 45 years of long distance running at near maximum effort failed to prevent coronary artery disease and likely is the cause of my history of atrial fibrillation and high CACS. This is my anecdotal story and I’m sticking with it! Almost all of my many relatives live to their mid to late 80’s. My maternal grandmother made it to 94. Workers all, none exercised.

With the qualifications that I am an ophthalmologist by way of general practice, I present my conclusions on ‘preventive cardiology’ delivered from my editorial bully pulpit.

For most people, 30 minutes of walking, even if broken into multiple shorter intervals, 5 to 6 days per week will accrue almost all the benefits of exercise with the lowest possible risk of adverse events. It’s a regimen that might reasonably be sold to an increasingly slothful and obese public. Please view “23 and One Half Hours” on You Tube and recommend it to your patients.

Maximum effort, endurance exercises/sports greater than one hour duration should be discouraged, especially in those over 40. Patients should be informed of the potential that such activities can cause increased rates of cardio-vascular disease, even death, in some participants.

The Heart CT should be used more often as a tool for finding unsuspected coronary artery disease. All endurance athletes over 40 should have a Heart CT and be considered in a higher cardiovascular event risk cohort.

After 40 most people should be on a statin (every cardiologist I know is so why shouldn’t our patients be?), a baby aspirin and hypertension, even pre-hypertensive states, should be treated.

Despite the personal discomfort it often engenders, physicians must regularly address our patients’ problems of obesity, poor diet, smoking, lack of physical activity and excessive alcohol use.

In 490 BC, the world’s first marathon runner Pheidippides ran from Marathon to Sparta and then to Athens to announce the Greeks had defeated the Persian army. This was about 150 miles in 3 days. Herodotus states Pheidippides first words on arrival were, “Joy to you, we’ve won.” His next words were likely “My feet are killing me!” And they did; right then and there!!

Why has it taken physicians over 2500 years to understand that maximum physical exercise for very long periods of times are as unhealthy for their patients as for Pheidippides? I don’t know; it’s Greek to me.

Published: September 6, 2012