What happens to your body after running a marathon?

You finished that marathon and now you think that it’s all over. Well… that’s not entirely true. Yes, you’ve done your training and you’ve finished that marathon (well done!), but now it’s time for recovery.

I always have trouble sleeping the first night after a marathon, because I’m so sore I have trouble turning over in my sleep. The sore muscles in my legs will remain for about three days. But I also have trouble with my digestive system after a (half)marathon. This often results in a diminished appetite and sometimes even nausea after a race. That’s the reason I always put some Coca Cola in my race bag so I can drink it after the race. How long this lasts depends on the distance of the race, how much effort I put in and the conditions. After Paris the nausea was definitely worse than after running Berlin, but Paris was way hotter, so maybe it was due to the heat.

This happens because your body has to divert blood to the organs you need most during running (heart, lungs, and of course, your muscles). The higher the intensity of the exercise, the higher the necessity of diverting the blood so you can keep going. Since my heart rate is so high, running costs me roughly 50% more effort than someone with a normal heart rate and thus the physiological stress my body has to endure is higher. I assume therefore that it takes my body longer to recover, but I can obviously only speak for myself and about my own experience with recovery. Plus, everyone is different.


But the effects of running a marathon go way further than an upset stomach and some sore muscles. Lots of studies have been carried out on the effects of running a marathon on different organs. What surprises me about most of these scientific studies is that they do test the effects of running a marathon and what damage this does to your body, but they hardly ever look at how long it takes for this damage to be repaired. They check athletes before and just after the marathon, but that’s it. Very few of these studies have check-ups days, weeks or months after the marathon.


A study by Trivax et al. found that in two-thirds of tested athletes the right chambers of the heart were dilated after running the marathon. But they didn’t check at which point after the race the heart got back to normal. Other studies have also found elevated cardiac biomarkers after a marathon, but these studies have found that the levels returned back to normal roughly 2 days after the marathon.


Whilst running a marathon you get dehydrated, either a little or a lot depending on the circumstances. This won’t be appreciated by your kidneys, but research has found that your kidneys do recover in about two days.


I definitely know the feeling of trying to get down the stairs right after a marathon (in both Paris and Berlin I had to take the metro to get back to my hotel and metros have a surprising amount of stairs). And I’ll still feel that muscle soreness for about 3 days after the marathon. According to doctors it might take up to 3 weeks for the muscle damage to be completely repaired.


Running a marathon also asks a lot from your joints. Vuolteenaho et al. found that there was an increase in biomarkers of cartilage destruction. The faster the marathon was run, the higher the increase in biomarkers. Again there wasn’t a follow up. But according to other doctors it might take up to 3 months for the cartilage to repair itself, although some question if it even completely repairs itself at all. But I don’t want to get into the “running is bad for your knees or isn’t bad for your knees at all” controversy right now.


Takayama et al. didn’t find any differences in VO2max before the marathon compared to one week after the race. Thus suggesting that maximal performance capacity are restored after a week. (I don’t know about you, but I don’t feel ready to run another marathon one week after the previous one. I’d rather keep it to two marathons a year.)

Another thing I’ve noticed about these studies is that they are often carried out on a small group and it’s not uncommon for that group to only contain men. So, in about half these studies I wonder what their added value really is. So, bottom line still remains that running a marathon is quite hard on your body and it varies from person to person how quickly you recover.


Predel, Marathon run: cardiovascular adaptation and cardiovascular risk, European Heart Journal, 2014.

Takayama et al., Effects of Marathon Running on Aerobic Fitness and Performance in Recreational Runners One Week after a Race, Journal of Sports Medicine, 2017.

Trivax et al., Acute cardiac effects of marathon running, Journal Appl Physiol 108: 1148–1153, 2010.

Vuolteenaho et al., Running a Marathon Induces Changes in Adipokine Levels and in Markers of Cartilage Degradation – Novel Role for Resistin, PLoS ONE 9(10): e11048, 2014.

NRC, Hart en knieën krijgen de klappen, 2017.

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