Optimal Exercise Dosing: Is There Such a Thing as Too Much?

May 13, 2016 | Nick Ierovante, DO

The general consensus amongst physicians is that regular exercise is typically good for overall health and inactivity is typically bad. For many of us, being a FIT has meant several city, state, country or even continent moves over the last several years. While many of us strive to engage in healthy behaviors including regular exercise, these frequent major life changes can make sticking to a routine difficult. As a mean to fight these changes, many fellows choose endurance running. It can be done in any place, at any time, no matter your geographical location, making it easier to realistically incorporate into daily life. I consider myself fortunate to have ended up in an area with a strong running community which holds a half marathon in the spring and a full marathon in the fall. This has created a niche in the local population that consists of novices, intermediate and seasoned runners and gives me an opportunity to care for these patients from time to time.

While runners tend to be leaner, less likely to smoke, suffer less disability later in life and tend to have an increased survival advantage compared with nonrunners, occasionally they still do need to see the cardiologist. I recently had the opportunity to care for one of these patients, a middle aged mother of four who presented to our Emergency Room with presyncope and palpitations following her morning workout and was subsequently diagnosed with new onset atrial fibrillation (AFib). Her major social activity was running, which she initially began in high school. As she got older she ran more, and more and more. At the time of our meeting, she was covering between 35 and 40 miles a week. Her thought was, if some exercise is good, more must be better, which appears to be a common conclusion that the general population makes.

Gradually increasing exercise intensity, frequency and capacity over the course of a lifetime seems like an intelligent and intuitive approach to maintaining overall health. However, there is such a thing as “too much”. The classic example is that of Phidippides, a running carrier in ancient Greece, who died suddenly after running 26 miles from Marathon to Athens. While the overall risk of cardiac arrest or sudden cardiac death during a half or full marathon is low, endurance athletes have been shown to be at greater risk of Afib  and when looked at over a long period of time, strenuous runners may not have a mortality rate much different than sedentary people. In this registry study, joggers were separated into light, moderate and strenuous groups based on pace, quantity and frequency jogging. The authors concluded that compared to sedentary people, joggers had lower mortality rates when they jogged at a slow to moderate pace (approximately five miles per hour), for 1 to 2.4 hours per week, with a frequency of less than or equal to one to three times a week. However, when going above these limits, all-cause mortality increased, with the strenuous joggers having no statistically different change compared to the sedentary group. As I continued my patient visit, I discussed with her the available data from the literature, reviewed her personal goals and it was ultimately decided she would back off her weekly running somewhat, but would still run in the half and full marathons this year.  While I’m sure most of us would love to have excessive exercise be the major concern for our patients, it is still an issue that comes up from time to time. By knowing what data is out there, realizing what is lacking in the literature and having frank conversations with our patient about their goals and expectations, we can be ready for any situation and maybe heed some of our own advice.

This article was authored by Nick Ierovante, DO a fellow in training (FIT) at the Wright Center for Graduate Medical Education.