When Dr. Kenneth Cooper published his first bestseller, “Aerobics,” 40-some years ago, he simultaneously introduced a new word into the Oxford English Dictionary. This book, translated into 41 languages as well as Braille, propelled Dr. Cooper to the forefront of the pro-exercise movement.  In fact, he has been credited with motivating more people to exercise for health benefits than any other single individual.  As the good doctor puts it, “It is easier to maintain good health through proper exercise, diet, and emotional balance than to regain it once it is lost.” 

Indeed, the Cooper philosophy has been thoroughly studied, researched, and validated in countless labs and fitness facilities around the globe.  While there is any number of ways to stay active, it seems that running has been one of the most popular forms of aerobic exercise through the ages.  Being able to power through miles and miles, eliciting endorphins and achieving that ultimate quest, the “runner’s high,” has mass appeal for athletes both young and old. 

While most recreational runners have a healthy respect for the limits of the human body, and set reasonable and appropriate goals for themselves based on their age and level of fitness, there are always going to be those individuals who feel that if a little is good, then more must certainly be better.  These are the hardy souls who engage in ultra-marathon events, or enter multiple marathons in a single season.  Interestingly, the medical research does not necessarily support that same adage.

Once the scientific community’s eyes had been opened to the fact that more is not necessarily better, additional studies began to appear in journals.  One such study published in the June issue of the Mayo Clinic Proceedings revealed that the effects of extreme endurance training, such as that engaged in by marathon runners, triathletes, professional cyclists, and ultra-marathon runners, could actually lead to long-term damage of the heart muscle.  According to Dr. James O’Keefe, lead author of the second study and a professor of Medicine at the University of Missouri and Saint Luke’s Hospital in Kansas City, MO, “There’s probably nothing better a person can do for themselves for their long-term health than daily exercise.  But if you train more than the cardiovascular system is designed to handle, you can tax your heart and do damage.”

While this news may not come as a surprise to some readers, it certainly will ignite the fury of our ultra-marathon fans.  However, pointing out the potential pitfalls can help alleviate serious health problems.  A study published in the European Society of Cardiology revealed that after completing 4 endurance races of varying lengths, seasoned athletes experienced diminished right ventricular (RV) function, increased levels of cardiac enzymes (markers for cardiac injury), and scar tissue on the heart muscle.  Furthermore, damage to the RV tends to cause electrical instability that may increase the risk of sudden death.

By now some readers may be wondering how something so beneficial could take such a dangerous turn.  To a certain extent, not allowing the body sufficient recovery time between events or training sessions can play a role in precipitating such damage.  However, a prudent way to look at exercise, and running in particular, is to liken it to a medication.  The dosage listed on the medication’s label is there for a reason; studies have shown that, when consumed at the prescribed dosage, the medication will perform optimally.  Similarly, when caring for the human body by providing it with aerobic stimulation, taking care not to exceed the heart’s upper limits will allow for optimal training results.

Surely there will always be those among us who will wish to push their bodies beyond a certain comfort zone, always challenging and always striving for maximal results.  Paying attention to appropriate limits will not only safeguard your heart, but will lend much more enjoyment to the run itself!