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Fitness

Science Says Excessive Endurance Training Too Much of a Good Thing

Ultrarunner Micah True, known to many as Caballo Blanco, died in March on a training run. Was his death indicative of the dangers of ultrarunning? Science takes a look.

Joshua Wortman

Written by Joshua Wortman Last updated on Oct 20, 2021

The old saying, “there is too much of a good thing” may actually hold some truth. On March 27, 2012, a 58 year-old ultramarathoner named Micah True died suddenly while on a 12-mile training run. If you read Born to Run you know Micah True by his other name, Caballo Blanco. True followed extreme running routines, and would run as far as 100 miles in one day. The autopsy of his heart revealed it was enlarged and scarred. It was determine the cause of his death was due to lethal arrhythmia, or irregular heart rhythm. The case suggests True’s heart problem may have been results of “Phidippides cardiomyopathy.”1

Phidippides was a Greek messenger who suddenly died after running more than 175 miles in two days. When hypertrophic cardiomyopathy (when the heart muscle becomes thick), anomalous coronary arteries (malformation of coronary vessels), and coronary atherosclerosis (progressive disease where atherosclerotic changes occur in the walls of coronary arteries) have been excluded from causes of death “Phidippides cardiomyopathy” is often dubbed primary reason for demise.2

Dr. James O’Keefe, of Saint Luke’s Hospital of Kansas City, Missouri, conducted research that suggests extreme endurance training can cause transient structural cardiovascular changes and elevations of cardiac biomarkers. These changes return to normal within a week. Some individuals who continuously train this way for months, however, experience repetitive injury to the heart that can lead to the formation of patchy myocardial fibrosis. Myocardial fibrosis is a condition that involves impairment of the muscles of the heart. It is a form of fibrosis, which means that the scar tissue of the heart hardens, making it inflexible, and can ultimately lead to heart failure.3 In one study, approximately 12% of marathon runners showed evidence of myocardial scarring, and the coronary heart disease event rate during a two year follow up was significantly higher than in controls.4

“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,” said Dr. O’Keefe. “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.”5

As with the Golden Mean suggested by the Greeks, there is an amount of any physical activity that carries the most benefit and least harm. As is possible with Micah True, ultrarunners may be testing that line regularly.

Joshua Wortman

About Joshua Wortman

Joshua began lifting in high school, but really doesn’t consider his effective training to have begun until the last few years. Joshua was always very strong for his bodyweight, but he didn’t just want to be strong, he wanted to look strong. At 140 pounds, no matter how strong he was for his age and weight, the size wasn’t there.

During his last year of college, Joshua began research on bodybuilding, and since his graduation, he has taken his bodybuilding to a whole new level. Josh experienced a minor setback in 2009 when he experienced an L5-L6 disc herniation while doing deadlifts. Consequently, his lower body training was very limited for almost a year. Thankfully, he has self-rehabbed his back to pretty much full strength.

Since he graduated from NC State University with his Bachelor’s in Civil Engineering, Joshua has taken his bodybuilding to a whole new level. His knowledge has increased ten fold since when he began, and both his knowledge anpersonal progress have also bred success in the fact he started up Get Right Get Tight Fitness.

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