How Do Those Marathoners DO It?
Esteve-Lanao J., et al. “How do humans control physiological strain during strenuous endurance exercise?”  PLoS ONE, 3(8), 2008.

I knew I was going to like this paper when I saw the first sentance.

“The image of the long distance runner evoke the popular fantasy of extraordinary effort.  Middle and long distance running competition represents the greatest degree and limitations of human locomotive endurance capacity.”

Awww, you’re making me blush!  Stoppit!  For those who don’t know me personally, in my normal life, I’m a distance runner.  I’ve only gone so far as half-marathons (next one comes up in December!) but someday I will run a marathon, and someday (cue dramatic music) I want to qualify for Boston, though I’m a major penguin, so this is probably only a pipe-dream.  Many of my friends give me strange looks over this, but hey, we all need a way to relax. 

I often get asked why I would do something so…insane (hey, you think I’m insane, talk to the ultra-marathoners who run 50-100 miles at a time).   Why would anyone do something the human body can barely handle?  After all, the guy who originated the marathon (the Greek soldier Pheidippides, who was the messenger from the Battle of Marathon to Athens) DIED when he got there.  My usual reply is that the guy ALSO fought a battle that day, probably didn’t hydrate along the way, and was probably wearing armor. 

Aside from Greek guys wearing armor, it appears that the human body is actually suited to some pretty long distance running.  It’s pretty unusual among carnivorous species, after all, the cheetah’s only good for about two miles (though it’s a FAST two miles).  There’s an idea out there that we evolved our distance abilities to fill a “persistance hunter” niche.  We may not be fast, but that wildebeast has gotta get tired sometime.  There’s no question that our bipedal form has also evolved to take walking and running over long distances.

Researchers know a lot about runners.  They know how they breathe, about their BMIs, what they eat, how fast they go, what their muscles look like and how they respond, what the heart is like, etc, etc.  They even know physical attributes that separate the elite runners from the pack.  But no one really knows what happens to the body DURING a race.  What regulates your body to make sure you can make it to the finish?  This is more than just a cool question, the answer could have implications for what actually goes wrong in those who suffer problems in marathons, allowing us to identify the problem before it’s too late.

So this study set out to find out what goes on in your body during a race.  Unfortunately they only looked in males (do women next, please!), but they looked at over 200 men (competitive runners, but not elites) over a training season, runnig 5k-100k.  They hooked all these guys up to heart monitors as they ran, examining heart rate, heart rate as compared to maximum heart rate, peak heart rates, relative velocities, and the metabolic intensity at which the runners were working over the period of the race. 

They found that physiologic strain (measured as a % of their maximum heart rate)  increased as the runners went for more distance (well, duh), and that strain was regulated as the men changed their pace.  But they ALSO found that physiologic strain DECREASED with relative distance.  This means that if you’re running further (a marathon as opposed to a 10k) your physiologic strain will be less per mile, as the body saves itself to go the full distance.  This was the case regardless of how fast the guys were going.  But I think the most important finding is this: in the cases where the runners had problems and had to stop or severely slow (this is called ‘hitting the wall’ and it’s a horrible experience), their physiological stress remained high even AFTER they stopped.  The body was acting like it was going the distance, even though the runner had stopped running.  This implies the body was failing to regulate itself, though more data will probably be required before we can say that was the cause.

I thought these results were fascinating.  It certainly proves that, with training, your body learns how to handle long distance, and is capable of dealing with the physiological strain during the competition and as you run.  It also has some really interesting implications for people who ‘hit the wall’.  More research is definitely needed to find out WHY the body’s regulation stops in these cases.  Measures of physiological strain could also be really important in identifying which runners might have problems during races.  Also, knowing that the body is still acting like it’s running could help doctors treat patients who have to drop out of the race for medical reasons.

In the words of John Bingham:  Waddle on, friends.

Esteve-Lanao, J., Lucia, A., deKoning, J.J., Foster, C., Earnest, C.P. (2008). How Do Humans Control Physiological Strain during Strenuous Endurance Exercise?. PLoS ONE, 3(8), e2943. DOI: 10.1371/journal.pone.0002943

2 Responses

  1. This is really encouraging information for people who want to become runners, but still suck at it. I guess it’s just time to be honest with myself that I’ve never really tried very hard to train my body for this kind of exertion.

  2. Also, if you follow these instructions to the ‘t’, using exact forms of URLs, you can send a trackback to the paper itself.

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