Marathons and heart risk: What endurance athletes should know

Posted: February 28, 2018

[caption id="attachment_12075" align="alignright" width="450"] Doing back-to-back marathons for many years in a row could have lasting effects on the heart.[/caption] Endurance athletes appear to be in excellent shape. However, recent reports have suggested that extreme endurance sports can be hard on the heart. Cardiovascular exercise is good for you, but taking it to the marathon, ultra marathon or Ironman triathlon level isn't always better. "Studies of marathoners have shown enlarged heart chambers and elevated heart enzymes after a race," said Dr. John Hayes, a Marshfield Clinic cardiologist. That sounds alarming, but the cardiovascular changes tend to disappear in a few days. More studies need to be done about the long-term effects of frequent participation in extreme endurance events, but most people shouldn't be concerned. The potential risk for competitive athletes shouldn't stop you from attempting a long-distance race or exercising in general. The benefits of cardiovascular exercise far outweigh any risks.

Frequency of endurance events probably matters

Running one marathon isn't likely to cause a lifetime of heart problems, so you don't have to quit your training program if finishing a long-distance event is your goal. Doing back-to-back events over many years may be another story. Patchy scarring, enlargement of the upper chambers of the heart, calcium buildup in the arteries and stiffening of the heart muscle have been reported in some competitive marathoners and ultra long-distance triathletes. It's not clear if these athletes had other risk factors for heart problems.

There is concern and some data that people who frequently participate in extreme endurance events are at increased risk for heart attacks and atrial fibrillation," Hayes said.

It's not clear how much is too much, but practicing moderation with endurance sports is your best bet. Give your body enough time to rest between races. Doing no more than one or two races per year is wise.

Take time to prepare and recover

Build up to longer-distance endurance events by training for shorter races. You should run several 5Ks, 10Ks and half marathons before training for a marathon. "Gradually building up your endurance over a long period of time is safer than picking an extreme endurance event and going to the max," Hayes said. Choose a training program that eases you into longer workouts, recommends rest periods after races and offers tips for returning to training. "Pay attention to clues your body isn't ready to start training again, like profound fatigue or trouble with dizziness and lightheadedness," Hayes said. Though your heart may be ready to train again, the rest of your body might not. Endurance sports are hard on the body. Athletes are at risk for overuse injuries like stress fractures and shin splints. Talk to your doctor if you have muscle and joint pains that don't go away with rest. Ease your way back into training when you feel ready. Start at the beginning of the training program, even if you think you're ready for longer workouts. Talking to your doctor about your plans to train for an endurance event is a good idea, especially if you have a heart condition or a family history of heart problems.

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