Last week I ran 20km and finished running at 1 am, went back home and slept without eating a lot. I spent the next three or four days feeling tired all the day, feeling like if my body was heavier. Yesterday I ran again 24 km, planned it a little bit earlier and came back home at 10 pm. I ate as much as I could (rice, fruits, vegetables) to compensate for the 2200 kcal I burned. Today I still felt the same, headaches and heavy body. Am I missing something important when it comes to food? Or should I have drunk some electrolyte drinks? What could cause this feeling of fatigue or is it just normal after long runs?

I am 86Kg, 1m87, I do my long runs at around 6min30sec per Km, starting with a heart rate of 150 which drifts until 170 near the end. Maximum heart rate around 200 I think.

PS: I am 26 years old, no back or knee problems, training for a marathon trying to follow this plan but my knees were like "NOPE" this is not going to work. I had to reduce the training days to 3 or 4 days per week. I never ran a marathon before.

  • What do you eat during your long runs?
    – JohnP
    Aug 17, 2015 at 20:39
  • Well if you mean few hours before, normal food like bananas and some other stuff. But during the run nothing, just a small bottle of water.
    – Mehdi
    Aug 17, 2015 at 21:51
  • 3
    If you're actually burning 2200 calories during your run, then you need to replenish during as well. If you edit your question and add your height, weight, average running pace and how long it takes you we can give a rough estimate of how many calories an hour you need to consume.
    – JohnP
    Aug 18, 2015 at 14:51
  • I edited my question.
    – Mehdi
    Aug 19, 2015 at 8:41
  • You ate rice, fruits, vegetables. To help your body recover, I would recommend much more protein. Sep 12, 2015 at 7:39

3 Answers 3


So you went for a long run for your current training level and felt tired for a few days afterwards?

That would be expected and rather the point. You're trying to stress your body so that it will adapt to the stress and then some (supercompensation). This process means that you will be a bit tired.

I'll note that some of the commenters wanted to calculate your calorie usage in order to replace it on the run. This is generally impossible. The combination of the maximum gastric emptying rate and ensuring the concentration of what you ingest doesn't cause osmotic problems mean that your maximum calorie intake is around 300kcal/hour. This is much less than the amount of energy you will be burning.

As you train, your body will become accustomed to using stored carbohydrate and fat stores to manage this.


Training for a marathon is a hard and feeling tired is normal. However the more you train the better you will start to feel. I trained for my first marathon with 4 runs a week, but I did find that I was tired and I also got injured. This was mainly due to adding to much mileage too quickly.

I am assuming that you were on week 3 (20k) of your plan and that you are taking your rest days. You should also be doing your long run in the morning to best represent your marathon start time. Your meal the night before and even two days before should be heavy with carbs. You should be drinking plenty of water during the run.

It is possible that you are dehydrated and your muscles can not properly recover, it is also possible that you are adding mileage to quickly.

Your LSD run should also be 35% of your total mileage for the week. So if you run 20k on your LSD run then the rest of the week should be about 40k. It is ok to rest and this is important so perhaps you need two days after you LSD run to recover.

The good news: You are young! Your body recovers much quicker than older runners.

My advice: Join a running group that is training for a marathon. Drink water and get lots of rest.


You may want to keep a lookout for sickness. While research has shown that, in general, exercise is likely to leave you less sick due to improved fitness, exercise is also stress on your body. Add to that that running generally involves being exposed to a lot of potential sources for infection from people to places (if you're actually in a race, you're literally surrounded by people who are constantly shedding bodily fluids and splashing them all around) and it's not horribly uncommon to get a bit sick after exercising. If you're not pushing yourself to exhaustion, it's generally pretty safe to continue exercising, but be aware that you may not be at your full potential, so consider that as a factor in avoiding overtraining.

I personally usually wind up with flu-life symptoms for a few days after intensive exercise, especially if engaged in after a period of relative inactivity, but without clinical testing, it's kind of hard to tell the difference between elevated temperature and sore muscles from your body recovering from the exercise, and from an actual illness you picked up.

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