John Davis

Written by John Davis


Why Runners Collapse During or After a Race

At this year’s New York City Half Marathon, reigning Olympic 5km and 10km champion Mo Farah of the United Kingdom took on Geoffrey Mutai, one of the best marathoners in the world.

Though Mutai bested Farah by a good 17 seconds, that wasn’t the biggest story of the day.

Moments after the finish, Mo Farah collapsed to the ground. He was immediately tended to by medical staff at the race and reappeared in good health not too long after at the post-race press conference to allay any fears, but it was still a nerve-racking incident.

As any veteran of endurance races knows, runners collapsing either during or after a race is not unheard of.  If you’ve been to enough races, you’ve probably seen this happen first-hand.

There are a number of reasons why athletes collapse on race day; some are relatively benign, while others are very serious. In today’s article, we’re going to explore some of those reasons so you can help prevent them and ease any fears a situation like this might have caused.

Causes of runners collapsing during and after races

A 2011 scientific paper by Chad Asplund, Francis O’Connor, and Timothy Noakes, three researchers and medical doctors from the United States and South Africa, investigated the various reasons runners collapse during and after races.

Heat stroke

Heat stroke is one potential cause—when you run hard, your body generates a large amount of heat, and if you can’t get rid of it effectively, this will result in an abnormally high body temperature. This in turn causes massive, body-wide problems, which manifest as confusion, dizziness, vomiting, and collapse.

Dehydration can increase your risk of heat stroke, but it is not the only cause. Outside temperature and a rise it internal body temperature from working hard can also cause heat stroke. And while heatstroke is more common on very hot days, it can happen even on days with moderate weather.

Here are 6 helpful strategies for how to perform well and race safely in the heat.


Hyponatremia, a drop in the sodium that circulates in your blood, is another possible cause of collapse.

Typically, this occurs in runners who drink far too much water during a race, which dilutes the sodium in their blood so much that it disrupts their body’s normal biochemistry. Hyponatremic runners also commonly vomit, become confused, and collapse.

Athletes at greatest risk are novice runners or slower runners who may take 4-5 hours or more to finish a marathon and who are drinking mainly water. These runners often have an easier time drinking while running at a slower pace and also have more time and opportunities to fill up on fluids.

As the marathon and other long-distance races become more popular, especially among newer recreational runners, more athletes are likely to be at risk for hyponatremia.

For a more in-depth look at hyponutremia and how you can prevent it, here’s a great article written by our nutritionist Emily Brown and based on the work of Dr. Tim Noakes. You can also check out our podcast with Dr. Noakes himself.

Heart conditions

Traditional heart disease can lead to a heart attack during a race, even in apparently healthy middle-aged runners, and many young runners train and race with undetected congenital heart conditions.

One study done in Italy, which requires all young people to undergo cardiac testing before participation in sports, found that 2% of all young athletes had potentially dangerous heart abnormalities. Every year, a handful of high school and college athletes suffer sudden cardiac arrest during athletic events.

One well-known case occurred in 2008, when professional runner Ryan Shay collapsed and died only five miles into the Olympic Trials Marathon.

It’s always advised to consult your doctor before jumping into a training program, especially if you haven’t been exercising regularly before starting.

Postural hypotension (the most likely cause)

As worrying as the three conditions above are, there is some good news

Asplund, O’Connor, and Noakes point out that the majority (though not all) of runners who collapse after reaching the finish line of a race are likely suffering from a relatively benign condition called postural hypotension.

This happens in part because you’ve stopped running.

  • During an all-out effort, like a race, your heart rate is sky-high, and as a result, so is your blood pressure. 
  • Additionally, the rapid, rhythmic contractions of your muscles while you run provide a strong pump-like effect on your blood vessels, encouraging blood to circulate back from your legs.

Once you hit the finish line, both of these mechanisms cease.

The result is a sudden drop in blood pressure, which produces dizziness, fainting, and collapse, much like when you stand up too fast after sitting or lying down for a while.

Collapse from postural hypotension still needs medical attention, and Asplund, O’Connor, and Noakes provide guidelines for medical personnel treating collapsed runners. But it’s easily treated with leg elevation and oral rehydration, and it’s not a life-threatening condition.

News stories report that this is exactly what happened to Mo Farah after his half marathon.

Final message

To be sure, there are several very serious life-threatening medical problems that can cause a runner to collapse, even after crossing the finish line. But research suggests the runners who are most likely suffering from a serious problem tend to collapse during the race, and most of the runners who make it to the finish line before collapsing are going to be okay.

Still, any collapsed runner needs medical attention right away.

Knowing the various reasons why a runner might collapse in or after a race could save a life, so it’s worth learning!

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1. Asplund, C. A.; O'Connor, F. G.; Noakes, T. D., Exercise-associated collapse: an evidence-based review and primer for clinicians. British Journal of Sports Medicine 2011, 45 (14), 1157-1162.
2. Armstrong, L. E.; Epstein, Y.; Greenleaf, J. E.; Haymes, E. M.; Hubbard, R. W.; Roberts, W. O.; Thompson, P. D., Heat and cold illnesses during distance running: ACSM position stand. 1995.
3. Noakes, T. D., Hydration in the marathon: using thirst to gauge safe fluid replacement. Sports Medicine 2007, 37 (4-5), 463-466.
4. Noakes, T. D., Lore of Running. 4th ed.; Human Kinetics: Cape Town, 2001.
5. Corrado, D.; Basso, C.; Pavei, A.; Michieli, P.; Schiavon, M.; Thiene, G., Trends in Sudden Cardiovascular Death in Young Competitive Athletes After Implementation of a Preparticipation Screening Program. Journal of the American Medical Association 2006, 296 (13), 1593-1601.

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4 Responses on “Why Runners Collapse During or After a Race

  1. Just want to know how does VO2 max work and how do I use it my running correctly I have seeing in the articles on runners connect it talk about persentages of VO2 max being used while running I just want a better understanding of VO2 max and how do I apply it in running?

  2. I just ran a half marathon after a day of being sick, I collasped afterwards and was taken to the er. My blood pressure had dropped to 70/30, After being treated I was just left with a headache.I will never run a race again if I am not feeling well. I think we all dont take not feeling well serious enough before setting out to run. Listen to your body.

    • Hi Susan, thanks for sharing. Sorry you had to go through that, but you are exactly right. Now that you have learned your lesson, you will appreciate your training so much more in the future. For now rest up, and feel better!

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