Why the Marathon Can Be Tough to Finish

Marathon Runner

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Marathon finishers wear their medal with pride. It is a badge of honor, a signal to the rest of the world that you are tough and made it through a grueling long-distance race. Whether you ran the whole course, did a run/walk technique or were a pure walker, you faced a supreme challenge.

As the story goes, the first marathoner, Pheidippides, who raced 150 miles from Athens to Sparta before the Battle of Marathon, declared "Nike!" (which translates as "Victory") and then dropped dead from exhaustion.

Everyone's marathon experience is unique. The challenges you may face may be different. But these are the top reasons that running a marathon is so tough.

Hitting the Wall

The 26.2-mile marathon is a challenging running event because of its duration. After two hours of running (by the 20-mile mark for fast runners), the body runs out of carbohydrates and glycogen (stored energy in the muscles) and begins burning fat stores in the body for fuel. Runners call this "bonking" or "hitting the wall."

When you hit the wall, you may experience feelings of severe weakness, fatigue, confusion, and disorientation. You might feel slow, heavy and weak. If you keep going, physical exertion becomes increasingly difficult and you may even start to experience muscle trembling and shaking, sweating, and lack of coordination.

The problem with fat-burning for energy is that it uses more oxygen, which only further depletes a marathon runner's energy. If they don't refuel with carbohydrates soon, they will bonk.

If you are doing a run/walk technique or purely walking a marathon, you probably won't experience the wall. At a slower pace, the body uses fat stores for energy throughout the event and doesn't need to start burning up its own muscles instead.

You can prevent bonking by ensuring you have sufficiently carbohydrate-loaded prior to the race. During the race, you can take in enough calories with energy snacks and carbohydrate-containing sports drinks to keep your energy stores from being completely drained.


Those who aren't careful to drink the right amount of water and electrolyte replacement drinks during the race will feel the effects of dehydration or hyponatremia (excessive hydration). Common signs of dehydration include:

  • Concentrated urine that appears darker than normal
  • Dry lips and tongue
  • Dry, sticky mouth
  • Headache
  • Nausea
  • Weakness, dizziness, or extreme fatigue

Symptoms of hyponatremia, a dangerous dilution of the electrolytes in your bloodstream, may include nausea and vomiting, confusion, weakness, and in severe cases, seizures, coma, and even death.

The general recommendation is to drink when thirsty and use an electrolyte replacement drink at full strength throughout the marathon. This works well for the majority of racers. But for some individuals, factors such as age, medications, and certain health conditions put them at a higher risk for dehydration.

During your marathon training, weigh yourself before and after a long workout. If you are replacing fluids correctly, you should see no change in weight.

Racers who don't trust their thirst mechanism but instead drink at every stop can get into fluid overload. This can result in hyponatremia.

Marathon courses generally provide drinks, but even large events have disasters where they run out of water or sports drink or can't keep up with the mass of runners. If you are one of the slower racers, you may encounter closed hydration stops, so it is wise to carry your own sports drink to have when needed.


The average marathon runner finishes the race in about 4.5 hours while the typical walker takes 6.5 to eight hours to finish. That is a long time to be out in the elements exerting yourself. Blisters, chafing, sunburn, and heat illness are common hazards. Muscle strains and sprains are more likely due to fatigue during the race.

By gradually building your mileage during several months of training, you will help toughen your feet and build the muscles, energy systems, and mental endurance you will need for the marathon.

After a marathon, the strain on the body is apparent. Marathoners get tiny tears in the muscles and there is a build-up of the toxic breakdown products from exercise—lactic acid, etc. You will need to expect a recovery period of at least a week with only light activity before getting back into your workout routines.

A Word From Verywell

By being so tough, marathons also, in a way, become addictive. While some people can do "just one," and most vow never to do it again after their first, plenty of people get hooked on seeing if they can improve their times from year to year.

Hal Higdon, who has run over 100 marathons, writes in his book, "Marathon": "In a marathon, you don't beat others. Instead, you achieve a personal victory." It is a very personal event, each participant having their own goal to achieve, often just to finish.

9 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  4. Knechtle B, Chlíbková D, Papadopoulou S, Mantzorou M, Rosemann T, Nikolaidis PT. Exercise-associated hyponatremia in endurance and ultra-endurance performance--Aspects of sex, race location, ambient temperature, sports discipline, and length of performance: A narrative review. Medicina (Kaunas). 2019;55(9). doi:10.3390/medicina55090537

  5. Maharam LG, Siegel A, Siegel S, et. al. IMMDA's health recommendations for runners and walkers. IMMDA Body.

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  8. Cleveland Clinic. 6 tips to prevent marathon training injuries.

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Additional Reading

By Wendy Bumgardner
Wendy Bumgardner is a freelance writer covering walking and other health and fitness topics and has competed in more than 1,000 walking events.