What Happens When You Run a Marathon?

Running a marathon isn’t one of those bucket list items you can check off on a whim. Completing a 26.2-mile run requires extensive training, personal motivation and a willingness to endure the toll such extreme exercise takes on your body.

If you’ve done the work and are preparing for your first big race, it’s important to know what happens when you run a marathon. What should you expect, and how can you avoid the common pitfalls that keep many marathoners from crossing the finish line?

Prepare for Pain

“Those first few steps of a marathon feel amazing,” said Jon Harrington, 37, a financial planner from New Market, New Hampshire, who has run more than 15 marathons, completing the Boston Marathon six times and the JFK 50 Mile Memorial ultramarathon. “In Boston, you start off going downhill and running fast. That’s a good feeling. But each step gets harder. Your body gets more and more tired, until about mile 25, when you can see the light at the end of the tunnel.”

That doesn’t mean the race is torture. Between the excitement of the event and the cheering crowd, Harrington said he often feels runner’s euphoria throughout the race. Still, the experience is painful for even the most seasoned marathon runners, because running such long distances causes microscopic damage to your leg muscles.

Your feet also take a beating, resulting in painful blisters and even lost toenails. “I’ve lost many toenails,” Harrington said. “During the JFK 50 Mile, I lost both big toenails by the end of the race. Other times, they’ve just bled or turned black.”

Pain is inevitable, but the more you train, the better prepared your legs will be for the challenge. Be sure to train in the same socks and shoes you plan to wear on the big day.

Stay Properly Hydrated

Hydration is important during a marathon. The more you sweat, the more water and sodium your body loses. Dehydration places extra stress on your kidneys and can cause muscle cramps.

You need water and electrolytes throughout the race, but pace yourself. During intense endurance exercise, blood is pulled away from your kidneys to power your muscles, so your kidneys can’t filter as much water as usual. If you over-hydrate, you risk developing hyponatremia, an imbalance of electrolytes that can lead to dizziness, confusion and brain swelling.

Marathon volunteers usually pass out water and sports drinks along the way, but Harrington still wears a hydration belt and takes sips throughout the race.

Stop for Snacks

Running a marathon requires a lot of energy because you burn more calories than during regular exercise. Your body usually relies on slow-twitch muscle fibers for forward movement. During a marathon, it recruits all your muscle fibers, including the fast-twitch fibers that it usually reserves for sprinting, according to ABC News. This requires much of your blood supply and depletes the carbohydrate energy you stored before the race. Unless you replenish your energy supply, your body will start breaking down body fat and muscle protein and you might feel like you’re hitting a wall.

That means it’s time to eat. “I often stop for bananas or orange slices,” Harrington said. “During the JFK 50 Mile, I was eating meals like soup and peanut butter sandwiches.”

Scope Out the Port-a-Potties

Unless you chug fluids beforehand, you might not need to urinate during the race. Once your body heats up, it needs the water. If nature does call, you can usually find a port-a-potty and get back on your way quickly.

Your bowels, however, might give you more trouble than your bladder. The journal Sports Medicine estimates 30 to 50 percent of distance runners experience intestinal problems during a race, ranging from nausea and gas pains to runner’s diarrhea. As Bill Rodgers, four-time winner of both the Boston and New York City marathons, once said, “More marathons are won or lost in the porta-toilets than at the dinner table.”

Fiber, fat, protein and fructose increase your risk of developing runner’s diarrhea. If you’ve had this problem before, limit your intake of high-fiber or fatty foods for a day or two before the race.

Protect Your Skin

When dressing for the race, choose breathable fabrics to help prevent chafing. You might also need a lubricant, especially on your nipples.

“If you’re a man and you run a marathon without putting Vaseline on your nipples, they will be bleeding,” Harrington said. “You only make that mistake once, usually during training. It’s better now with performance clothing. But if you wear cotton, you will have a problem almost immediately. Even with good clothing, you need lubricant. I cover my thighs, armpits, knees and all along my feet.”

Nipple bleeding is less common for women but underscores the importance of a breathable and well-fitted sports bra.

Plan for Recovery Time

Don’t make any big plans for the few days following a marathon. You will experience muscle soreness, tightness and swelling for about a week.

“Crossing the finish line is an awesome feeling,” said Harrington. “People are cheering their heads off. Someone covers you in a foil blanket and you get a medal, but you know you just ran a marathon. You walk funny. You’re very hungry. The real pain comes the next few days. Sometimes it waits a day, sometimes it doesn’t. But soon your whole lower body is just stiff and sore. You feel that way for a week, and then it goes away.”

Considering what happens when you run a marathon, how is the gain worth the pain?

“At first, it’s about the personal achievement,” Harrington said. “It’s something that’s hard to do, especially the first time. At some point, it gets fun and turns into a community thing. Friends will often say, ‘Hey, you wanna go run this marathon with me?’ If you keep up with your training, later efforts to finish the whole race become less of ordeal.” Just don’t forget the petroleum jelly.

*The content on this website is for informational purposes only and is not medical advice. Please consult a physician regarding your specific medical condition, diagnosis and/or treatment.

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