Posted by: Dean Hebert | September 9, 2008

Does Ultra-marathoning cause permanent damage to your body?

Coach Dean Hebert

Coach Dean Hebert

A reader named Jason asks a question that may be of interest to runners who one day move up to the Ultra didstances. Coach Dean takes this one on for us:

I have recently been told by a well established ultra running coach that ultra running could permanently damage your muscles, possibly change your brain chemistry, and hurt your heart if you do it without proper training. I am somewhat new to running and have been using the Galloway method of walk breaks and hard/easy days/weeks for my training. I recently finished the White river 50 in 11:45 with no ill effects feeling pretty good at the end. I don’t run a large volume of miles weekly, but I do run monthly marathons at a very relaxed pace and do lots of long runs. Am I in danger of ruining my muscles for life? What is the truth about long endurance events, do they damage you permanently?

The short answer is most likely you will not be causing permanent damage to your body by running ultramarathons.

Now for the longer answer.

I’ll start with a disclaimer — I have found no solid research of any kind on this topic. It’s a tough area to study. It’s a small population to study. The smaller the population, the smaller your study sample and therefore the less valid or generalizable your results – there are just too many exceptions.

Much of what exists is anecdotal – much like your “well established ultra running coach.” Which, though valid from his own unique view, does not speak to the “world” of ultra runners. And just to drive this whole point through, it could be what he sees is a result of the training approach he uses with his athletes not ultramarathoning in general. (I’m not saying the training IS the cause. I’m saying when you rely on anecdotal information – by nature – it is skewed.)

What has been studied (although still relatively limited by comparison of running in general) is muscle damage from the event itself. To no surprise, British and Japanese studies found various enzyme changes indicative of high body stress reactions; the British study also found some hepatic (liver) damage post-ultramarathon. However, it did not state it was permanent.

The Japanese study showed some heart muscle “damage” after an ultramarathon; this can be likened to the damage we see in skeletal muscles after a prolonged run. However, they showed that the blood chemistries for this indicator returned to normal by the following day. The Japanese study specifically stated, “Whether these changes have long-term negative effects in the organism needs further investigation.”

An interesting aside in this study is that contrary to what is being reported in some marathon studies, they found hyponatremia is rare in these events.

Another study was done during the 100 mile Western States Endurance Run. It compared users of NSAID pain-relievers (72% of athletes) with nonusers. They concluded that muscle damage in athletes competing in a 100 mile race was significantly correlated with post-race DOMS. NSAID users did not experience a reduction in muscle damage or DOMS! Again, this is only a short term effect. Similarly, a Greek study concluded that antioxidants appeared to have no effect on exercise-induced increases in muscle damage or recovery. The antioxidants simply did not prevent muscle damage in response to an ultramarathon run.

You are training at modest miles overall and that is a good thing. It allows for recovery to your various body systems. Keep up the monthly marathons. These will help condition you and prepare you for your ultra. This is a sound approach to ultra training. Do not succumb to huge training mileage. Be sure to recover well during your training program as well as after the race.

I’ll add this final note. In any athletic endeavor with prolonged punishment there may be a risk of long term injury. They have found this to be true with a number of former professional football players for instance. There is no doubt that genetically we are all engineered differently and that may end up our biggest limitation. (i.e. if you are injury prone, you’ll stop doing all this; sort of like Running Darwinism) If you run within yourself; read your body; and take all reasonable precautions, there is no reason to believe at this time that permanent damage is being done to your body.

Coach Dean Hebert, Tempe Arizona USA
Contributing Editor, Running Advice and News


  1. […] beyond one-off the injuries or pain after a particular tough race or training. Coach Dean Herbert posted about this on Although there are no links to any of his sources, he points out a few studies on this subject. As […]

  2. […] This particular question asked by a wonderful visitor is one that I have worried about and asked myself.  I was so worried that I contacted a coach for ultra-marathoners to get his advice.  Here is a link to the question that I asked.  It was posted on the coachs’ blog. […]

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