Did You Know These Potential Adverse Cardiovascular Effects From Excessive Endurance Exercise?

Graphic – herbshealthhappiness.com Image sources – see foot of article

Cardio is generally beneficial for health, but it could become harmful to your heart when taken to excessive lengths. This generalization was posited by a 2012 study ^[1] published in the journal Mayo Clinic Proceedings that warned of the long-term harm posed to the cardiovascular system by excessive endurance exercise such as marathon, ultramarathon, ironman distance triathlons and very long distance bicycle races. These activities may cause structural changes to the heart and enlarge arteries, says the study.

According to lead author Dr. James O’Keefe, regular daily exercise is effective for the prevention and treatment of diseases such as obesity, hypertension, heart failure, and coronary heart disease. However, extreme endurance training can cause musculoskeletal trauma and cardiovascular stress. The study associates ultramarathon running and professional cycling with five-fold increase in the prevalence of abnormal heart rhythms.

In an interview with the magazine “Runner’s World”, Dr. O’Keefe clarified that a single marathon is not necessarily bad for a person. He noted that what is bad for one’s health is to do 10 or 15 marathons a year for 20 years. ^[2]

O’Keefe compared the benefits of exercise to a powerful drug. He explained that any potent drug has an ideal dose. This dosage should be enough to bring full benefit. Too much of it can cause dangerous side effects. He applied the same analogy in the benefits of exercise. He said that when people do more than an hour of strenuous exercise, they could lose some of the health benefits seen with lesser amounts of physical activity. The study author suggested to getting into exercise patterns that promote overall health and longevity.

The Mayo Clinic doctor stressed the importance of just thirty minutes of moderate or vigorous physical activity. He mentioned the influence of a daily exercise habit on cutting one’s risk for premature death, diabetes, Alzheimer’s disease, depression, and heart attack. He added that people who exercise regularly have lower rates of disability ^[4] and longer average life expectancy than sedentary people. ^[5]

O’Keefe’s findings are supported by other studies. One was presented at the Canadian Cardiovascular Congress in Montreal, Quebec in 2001 that showed the impact of long-distanced running on cardiac risk. ^[3] First published in The American Journal of Cardiology, the study linked long-distance running to high levels of inflammation that may trigger cardiac events.

Another study published in the Journal of Physiology in 1985 even discovered grimmer news about excessive endurance exercise. ^[4] The study focused on extremely fit older men who had successfully run in a minimum of one hundred marathons. It hypothesized that marathon running could provide a cardiovascular benefit to this group of men. Well, Wilson M et. al. discovered that half of these marathoners showed some heart muscle scarring, especially the ones who had trained the longest and hardest.

Heart scarring was also the health issue developed by male rats which were subjected to intensive exercise training to mimic the strenuous daily exercise load of serious marathoners. ^[6] Before the study was conducted, all the rats had normal, healthy hearts. The study documented diffuse scarring and some structural changes in the cardiovascular system after long-term intensive exercise training.

O’Keefe et. al. and other studies are an important reminder that the human heart does not regenerate itself and that humans only have one heart. While skeptics can continue to emphasize the fact that these studies are small and non-randomized, more evidence for the relation between extreme exercise and the subsequent adverse structural remodeling of the heart is mounting – and should not be ignored.