Marathons and Heart Damage

By Mark Sisson

Marathon running is supposed to be good for you, which is why so many people (intend to) do it. The overweight and the untrained often use the successful completion of one as a landmark on their weight loss journey, sometimes the goal itself. Others think, erroneously, that it’s part of an anti-aging strategy. If you can run a marathon, you are fit, or so the story goes.

New MRI data out of the Heart and Stroke Foundation suggests the contrary: that “less fit” runners running a marathon are damaging their hearts for up to three months. The musculature of the human heart is made up of 17 segments. If one segment fails due to stress (say, from a marathon), adjacent segments pick up the slack. Unfit marathoners exhibited abnormally high amounts of overly stressed heart segments. Their hearts were working harder, and the work was concentrated across fewer segments. These abnormalities persisted for as long as three months after the marathon.

Okay, exercise induces muscle damage as a rule. That’s how we get stronger – by undergoing stress and muscle damage, and adapting to it by rebuilding our muscles stronger than ever. But muscle damage isn’t supposed to last for three months. Sure, even the study’s authors admit that the damage is reversible, but is that really an effective way to train?

The problem is that there’s no built-in shut down code in our central nervous system when it comes to running a marathon. The heart muscle doesn’t sense the “pain” of exertion the way leg muscles do. It just tries to keep up with the demand to pump more oxygen. Total beginners with a new pair of $150 Nikes (with shock absorbers, stabilizers and motion control) and a fanny pack full of glucose gel can sign up for a marathon and (just) do it. It’s not so traumatic an ordeal to trigger an automatic response; it’s more drawn out and gradual a muscle stressor.

Beginners should probably not be running marathons. Truth is, I don’t even think experienced endurance athletes should be running marathons as often as some do (I keep tabs on all my old elite runner/triathlete friends who have had serious heart problems – or died – and it’s at a significant number now). But good luck getting that across. They – we – can be a stubborn bunch. If you want to get fit and you’re starting from scratch, lifting heavy things, engaging in slow steady movement often, and getting your diet in order are the most reliable, safest steps toward that goal. Running a marathon sounds badass and impressive, but remember – the first marathoner dropped dead after completing it. Myth? Maybe, but I wouldn’t take it lightly. If you insist on doing one, please train properly.