Experts explain just what's happening to you physically and mentally when you do 26.2 miles.
Jose Luis Pelaez Inc via Getty Images

Running a marathon is simultaneously thrilling, exhausting and gratifying. It’s a massive accomplishment ― albeit a physically and emotionally taxing one.

First-time marathoners are flush with advice from people who have already done it. They’ll hear things like, “It’s more mental than physical!” That they only have to run 20 miles and “adrenaline will carry you the rest of the way.” People have plenty of opinions about one brand of energy drink being better than another, advice about what the aspiring marathoner should or should not eat, that they can look forward to a runner’s high ― the list goes on.

Even when you’ve put in the training, fuel up safely and attempt to sleep the night before, there are some things that inevitably happen to the body and mind. Here are a few.

The anxiety will set in

Tapering ― the practice of running fewer miles and letting your body rest ahead of the marathon ― sounds great, but in reality can be extremely stressful. Sure, you ran 20 miles two weeks ago, but that was two weeks ago. How is a two-mile run a few days before race day going to equip you to run the big event?

Vice delved into this phenomenon in a January 2019 article about “taper madness.” Jim Taylor, a sports psychologist and marathoner, explained to the site the impact extreme exercise, or lack thereof, has on mental health. “During a long training period, we become addicted to the intensity and the volume, it becomes our norm,” he said. “To change that volume and intensity is disruptive psychologically and emotionally.”

Your heart will go on ― and on

According to experts, a marathon pace should be “easy” enough for the runner to have a conversation comfortably. Still, your heart rate is elevated, and stays elevated, according to Paul Thompson, chief of cardiology emeritus at Hartford Hospital in Connecticut.

“Your heart rate is not super fast because you can’t run that hard for 26 miles,” he told HuffPost. “Your heart rate will stay elevated for the next bunch of hours, how many hours depends on how fit you are.”

That’s why it’s important to keep moving after the race, even if your brain (and legs) want you to stop. It’s imperative to do this in order to safely lower your heart rate to a resting place.

You’ll be tempted to get ahead of yourself

The crowds, the excitement ― it’s easy for you and your training plan to get lost in it all. But going out too fast can have negative impacts later on.

A study of Chicago Marathon runners from 2005 to 2016 found over 50% of runners who ran too fast at the start were more likely to “hit the wall” later on in the race. Because, yes...

You might hit a wall

Sabrina Wieser, a long-distance runner and running coach, describes hitting a wall as having a completely empty tank. “There are no sugars or carbs left in your body, and that shouldn’t ever happen, but it does for a lot of beginners,” she told HuffPost.

But Wieser insists that with the right fueling strategy and training program, you should “not even get to that point.”

You’ll feel, er, crappy

Sad but true. With all the moving and bouncing, things are bound to start moving around in the body ― bowels included.

“You’re kind of pushing the fecal material along,” Thompson said. “But the other thing that’s happening is you’re not putting a lot of blood to the intestine, so you start sloughing the top layer of the intestine, like if you were sloughing off dry skin or something like that. Making it more raw.”

You’ll also feel incredible ― but not for the reason you might think

Runner’s high is widely chalked up to a release of endorphins, but it’s more complicated than that. According to a 2015 study, the blissful euphoria one experiences during running could also be due to a release of endocannabinoids, a chemical released in the body during exercise that’s similar to those found in cannabis.

Kind of gives the whole “high” thing a new meaning.

Your endurance will see you through

Most training programs don’t have the runner doing a full 26.2 miles. Because you don’t need to run that distance to get through the race.

“Once you do your longest run, 20 or 22 miles, you have the endurance and are ready to run 26.2,” Wieser said. “Everything after 20 miles is a total mental game. It’s a lot about mental toughness. You just have to be focused and stick to your game plan, your mantras, whatever you have ― you just have to keep your mind straight at that point.”

There will be pain

There’s no way around it. You’re putting intense pressure on your body for hours, and some damage is going to be done.

“There’s a lot of muscle damage,” Thompson said. “When you run and land, you stretch the muscle, so that leads to muscle injury. If you run a marathon, you injure your skeletal muscle, so your urine is darker because you have myoglobin in it, pigment from the muscle. It makes you sore and tired. You’re not so sore right after the race, maybe a little stiff. The next day, that’s called delayed-onset muscle soreness, and it just hurts the day after more than any time.”

But it’s worth it

There is absolutely no feeling quite like crossing the marathon finish line. You will marvel at your strength, what your body is able to do. Wieser put it pretty simply.

“You think, ‘Oh, my God, what did I do?’ You feel so strong, so empowered. I think it’s the greatest feeling ever, honestly.”

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