Exercise is good for us, right? Generally, that is right. But, like nearly anything there can be too much of a good thing when it comes to exercise. Don’t use this piece of news as an excuse not to exercise, though. People who exercise live on average 7 years longer than those who don’t and also live a better quality of life. But running marathons and participating in ultra-endurance events may put your heart at risk according to James O’Keefe, MD at Saint Luke’s Mid America Heart Institute. In this paper published in the Mayo Clinic Proceedings Dr. O’Keefe and his colleagues discuss the potential adverse cardiovascular effects from excessive endurance exercise. If you have been running marathons, or plan to, I recommend you take some time and watch his video interview.
Our Bodies Are Not Designed For Running Marathons
Our bodies are designed for short bursts of high intensity activities (running a 100 meters) and longer bouts of lower intensity exercise (walking 5 kilometers). They really are not designed for prolong periods of moderate intensity that typify marathons, triathlons, and ultra-endurance cycling events.
Watch how kids play, or how animals play. Have you ever seen a group of kids or a pack of dogs run down the street at a moderate pace for miles and miles? No. They run, they stop. They catch their breath. They run some more. They run, stop, change direction, catch their breath, and run some more, and so on. That’s called high intensity interval training.
Why Running Marathons Might Damage Your Heart
As Dr. O’Keefe says running one marathon probably is not going to hurt you, but running several and doing long ultra endurance cardiovascular training will exact a toll on the heart over time. Prolong endurance training (usually defined as more than an hour a day) is associated with elevated enzymes that suggest cardiac muscle damage. These are the same enzymes that are released during a heart attack.
Blood volume through the heart increases five-fold during intense exercise. When exercise is prolonged this leads to enlargement of the chambers of the heart, in particular the right atrium and right ventricle which are not well designed to handle excessive volume and pressure. This leads to enlargement and scarring of those chambers predisposing individuals to abnormal heart rhythms like atrial fibrillation and more deadly ventricular arrhythmias.
Some studies show marathon runners to have more calcium plaque in their coronary arteries. Rupture of a plaque is usually the triggering event leading to a heart attack. On the positive side, long-distance runners usually have coronary arteries that can dilate more easily and have better collateral circulation (the body’s way of bypassing a “blocked artery”). But the higher coronary calcium scores may outweigh these benefits.
Prolong endurance training triggers free radical production and oxidative stresses that are injurious to the cardiac cells. Though the body has its own natural antioxidant system, prolong endurance training can overwhelm it.
What Should You Do?
If you need to run a marathon because it’s been a goal of yours go ahead and train for it, do it, and move on to heart friendly activities. From a cardiovascular perspective we believe that high intensity interval training provides the best fitness and health benefits and only needs to be done two or three times a week. As little as 4 to 20 minutes per session can lead to significant health and fitness improvements. That might be more appealing than running marathons.
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