Is Running a Marathon Actually Good for You?

July 2nd 2015

My mother, who will be running her 30th marathon this year, insists that running is her antidepressant. She runs alone — no earbuds, no music — most of the time, save for the two- to three-hour Sunday "long runs" she does with friends, also marathoners. In the winter — which, in Montreal, is brutally, almost inconceivably cold — she still prefers running outside to the treadmill, coming home with icicles on her eyelashes and red, inflamed cheeks. I, meanwhile, am prone to tendonitis after even 15 minutes on the treadmill; I'll take medication over the torturous ambulatory alternative any day.

According to Greek mythology, the first-ever marathon runner, Pheidippides, dropped dead after his 26-mile run to Athens to deliver the news of Greece's victory at the Battle of Marathon. So why do tens of thousands of people participate in marathons every year, amassing participation medals and numbered paper bibs like high school trophies? (One reason may well be that past high school, there are precious few occasions that merit a trophy.) The stress that a marathon puts on the body may go beyond what qualifies as "healthy." Let's take a look at the anatomy of a marathon runner from head to toe.


Very few people, if they've given the matter any serious thought, set out to run a marathon with the goal of simply getting into shape. "You don't need to run 26 miles to get healthy. If that were the case, most of us would be pretty unhealthy," says Dr. Robert Weinberg, a professor of sport behavior and performance specializing in sport psychology at Miami University in Ohio. Anecdotally, he tells ATTN:, most people seem to run marathons for the tremendous sense of accomplishment -- the "I can do this" feeling.

Running also unleashes a flood of chemicals in the brain that produce the fabled "runner's high," including endorphins, norepinephrine, and serotonin, says Dr. Weinberg. Not surprisingly then, "aerobic exercise has a modest antidepressant effect," says Dr. Jerome Fleg, a cardiologist and medical officer in the Division of Cardiovascular Sciences at the National Heart, Lung, and Blood Institute.

Heart and lungs

Any aerobic exercise that involves endurance training, whether that's long-distance cycling, swimming, or running, is great for the love muscle -- the one in your chest. Compared with people who are largely sedentary, those who exercise regularly have lower levels of LDL cholesterol (the bad, artery-clogging cholesterol) and higher levels of HDL cholesterol (the "good" cholesterol, which actually helps clear LDL from the arteries), as well as lower blood pressure and better insulin sensitivity (which helps regulate blood sugar), says Dr. Fleg. Marathon runners also tend to be healthier eaters and aren't smokers, which also contributes to their lower risk for heart disease. As a result, long-term runners tend to have lower rates of death from cardiovascular causes, and studies suggest they may live longer overall, he says.

Aerobic exercise also helps the body process oxygen more efficiently, both by forcing the heart to pump more blood per heartbeat and increasing how efficiently muscles use up oxygen, says Dr. Fleg. "Any kind of endurance training, including marathon running, will increase one's aerobic capacity by about 20 to 30 percent, as measured by oxygen consumption during a treadmill exercise test."

But, paradoxically, some studies have shown that in the hours after running a marathon, runners have higher levels of regulatory proteins that signal heart damage and heart attack, although the significance of that elevation is unclear. The risk of heart attack during a marathon is still very low overall, usually occurring in people who already have underlying coronary artery disease or another cardiovascular risk factor that has escaped detection, says Dr. Jake Emmett, a professor of exercise science at Eastern Illinois University and a marathon runner himself. "It's maybe one in 50,000 to one 100,000 runners that actually die from heart problems while running a marathon, and the numbers are going down," he says.

Some long-term marathon runners also show signs of scarring to the heart, or fibrosis, on magnetic resonance imaging (MRI), which may signal a higher risk of cardiac complications than runners without that scarring. But, again, it's unclear what this scarring really means for long-term runners, or whether an MRI evaluation should be performed routinely in such individuals, Dr. Fleg explains. It does, however, make the case for encouraging middle-aged runners with a family history of heart disease to check in with a doctor before beginning to train.

Muscles and bones

Stronger, leaner, more defined muscles are the most visible benefit of training for a marathon. And because running is a weight-bearing exercise, it also helps strengthen the bones and protect against osteoporosis, which is particularly helpful for women approaching menopause, says Dr. Fleg. But the muscles, particularly those in the legs and the lower back, take on a tremendous amount of strain during a long-distance run. The further you go, the more you accumulate micro-tears in the muscle fibers, which your body then races to repair, causing temporary soreness and swelling. (The inflammatory proteins, called cytokines, that are released in response to damaged muscles may also be related to the elevated proteins in the heart post-race.)

Fortunately, these are short-term problems that tend to resolve with time and training. "Skeleto-muscular issues are more prevalent with first-time runners, just because they don't yet have the mileage," Dr. Emmett explains. "Their body isn't used to that much pounding and hasn't adapted to it yet. Those types of issues are usually reduced in experienced runners."


Running long distances also takes its toll on the joints of the ankles, knees, and hips. A marathon requires somewhere between 30,000 and 50,000 steps, according to a paper by Dr. Emmett, so your joints are practically acting as a punching bag as you pound the pavement. Naturally, short-term orthopedic injuries abound in long-time runners. "The more miles you're putting on your body, the greater your chance of wear-and-tear-type injuries," says Dr. Fleg. "That's just something everyone has to come to terms with."

But despite the common perception that runners may be more prone to chronic long-term orthopedic problems — think those requiring a hip or knee replacement — there isn't much data to back that up, says Dr. Emmett. "People who exercise regularly actually tend to have less incidence of hip and knee and joint problems than those who don't. But it depends; there are people who overdo it, or don't watch the shoes they run in or the surfaces they run on, and that can cause problems."

Immune system

Physically fit people tend to be less prone to colds and infections than more sedentary individuals overall, but there's a tipping point. Studies suggest that people who run marathons have weakened immune systems for several hours or even days afterwards, Dr. Emmett says, making them more prone to upper-respiratory infections (runny noses and the like) in the short term.


Running long distances not only revs up the metabolism, it keeps it fired up for hours afterward. According to Dr. Emmett, running a marathon at a pace of about five minutes per mile — admittedly a high bar for non-elite runners, and all but unattainable for first-timers — "requires a 15-fold increase in energy production over two hours." But even runners who take more than four hours to finish have a 10-fold increase in metabolism that lasts for hours afterwards.

Plus, says Dr. Fleg, "every mile that you walk or run burns about 100 calories, so if don't increase your food intake, you're going to have a negative caloric balance. This will, at least initially, aid in weight loss." But, he adds, diet, not exercise, is still the key ingredient for weight loss; regular runs are no match for daily Frappuccinos.

Going the distance

Planning to chase that runner's high? If you've never run before, or have concerns about a specific risk, talk to a veteran runner and/or a healthcare professional with experience in sports medicine. No matter how much advice you glean from the experts, though, every body will adapt and react differently to the strain of a marathon, says Dr. Emmett. "You just never know what to expect."

You'll never be able to fully injury-proof yourself or prepare for every inevitability, but adhering to a reasonable training regimen — building muscle endurance gradually, over many months, and giving your muscles time to recover — and paying attention to your diet and hydration needs will go a long way. And there are now whole volumes dedicated to training for a marathon that you can pick up. Fortunately, our understanding of what it takes to run one safely has advanced miles since the time of Pheidippides.

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