I'd love to get some advice on this one.

tl;dr: I can't figure out my calorie intake, and often end up dying in the middle of my 5k runs.

The longer version:

I've been running since August-ish, and have been trying to three 5k runs per week. In the last month I've gone from 32min down to 27:40. (That's just a bit of background).

About 50% of the time, I'll get 3/4 of the way through a run and completely run out of gas. And I mean completely. It's extremely frustrating—one day I'll have a good run, and the next, I'll be ready to pass out after about 20 minutes of running.

Here's what I had to eat today:

7am: Toast and peanut butter, coffee

10:30: apple, banana, coffee

11:30: a good-sized turkey sandwich

12:00 a granola bar

12:40 Run

Today, I got to about 22 minutes of fairly moderate pace and thought I was going to have to be carried back. I was dead. I didn't have a thing left.

The only runs where I find that this doesn't happen are my night runs — when I run after dinner (about 7:30-8pm). I find these runs go just fine when I eat by 5:30 and run after 7:30.

Any suggestions on how I might sort out my daytime running issues? An apple, a banana, a big turkey sandwich and a granola bar should be enough to fuel an 'easy' day run, shouldn't it?

Thanks for any ideas!

ps: I'm 6'2, about 200lbs. In 'reasonable' shape.

Update: So it seems like it's almost certainly a pacing issue. I've had 4 quite good runs now with no out-of-gas issues. I ran last friday on very little food, but watched my pace meticulously and had no issue. I didn't post a fast time, for sure, but I didn't run out of gas.

So the 'trick' to getting better at running is really improving your 'conversational pace'? When I started, I couldn't maintain a conversation at any pace, but now I can run for 30mins straight and be conversational the whole time. Again, not with a fast time, but I my heart rate isn't going nuts. I presume that with 6-8+ weeks of this, my 'conversational pace' will be faster? Is that how this works?

At any rate, thanks everyone for helping me sort this out. It seems obvious to me now, but it was quite a mystery before! Thanks!

  • eat moar? maybe add a protein shake in the morning of your runs?
    – DForck42
    Commented Oct 19, 2012 at 17:10
  • 1
    on a scale of 1-10 with 1 being sitting on the couch, and 10 being all out, what effort are you running? would be able to hold a conversation while running? Commented Oct 19, 2012 at 17:52
  • Today was actually my first day when I really actively tried to keep at the 'conversational' pace. Even at that pace, with that much food, I was all in!
    – saltcod
    Commented Oct 19, 2012 at 18:00
  • I would suspect something in your pacing is off. You should have more than enough glycogen in muscles and liver to sustain you for a 3 mile run. Time yourself and let us know your pace per mile, and also any information on other stuff beside running that you are doing.
    – JohnP
    Commented Oct 19, 2012 at 21:59
  • 1
    Update: It's pace. Ran the exact same route again today and discovered that it's most definitely pace. I ate more than enough food to keep me going, and found that I ran out of gas at exactly the same spot as last time — right after a good, steady hilly area. The route looks like this: 1-12mins: Flat 12-15mins: hills 15-> die! So if I can conquer my pace on the hill part, I should be good to go.
    – saltcod
    Commented Oct 22, 2012 at 16:58

6 Answers 6


Five kilometers is not much. In track and field, a 5 km race is confined to the track, and is considered "middle distance". This distance does not deeply tax the body reserves.

What's most likely happening here is simply that you're going too fast. You may also not have developed you pacing skills. Without realizing it, you may be going faster at the point where you bonk. You are warmed up, feeling good, and have only 25% of the distance left to cover, so your "afterburner" kicks in.

For any given fitness level, there is a pace at which the athlete will wipe out before hitting the finish. If, say, some elite male can run 10K in 28 minutes, and he tries a pace which shoots for 24 minutes, he will not be able to sustain that pace.

If you maintain a perfectly even pace throughout a run, which is fast enough that it feels very challenging near the end, that pace will feel very easy near the beginning. (And the longer the run, the easier. For instance a pace that feels challenging at the end of a 100 meter dash is not that easy at the beginning, either.)

Paces which are significantly faster than that pace still feel easy at the beginning! But those paces cannot be maintained all the way to the end.

So the feeling of what is easy at the outset of a run is deceptive. It is quite easy to "go out like a rocket".

Since you're into timing, if your stopwatch can take splits, then start taking them at key landmarks in your running courses. Then you know not only that you finished the run in 28:45, but also how fast you hit, say, quarter, half and three quarters.

On the other hand, do not be a slave to the stopwatch. This is probably one source of your problem. You are keeping track of your declining times for the 5K and that creates pressure. Last time you ran you "got it down to" 28:21. So today you want it under 28. And so it goes.

Not all your training runs can be time trials of the same distance in which you strive for continuous time improvement.

If you do that, you will blow up. Because after you run a personal best time, then for a while you are no longer an athlete who can do that same personal best. If you shoot for it again the next day or two days later, you may find it unattainable.

  • This is a fantastic answer Kaz. Thanks so much. I suspect you're right on many counts here. I was going out everyday truing to beat the lowest time I got on the day before. Good call. I had a great run yesterday — 6k (my first time) and I took it nice and slow the whole way. My time was way off, but I felt better at the end than I had before. I probably could have run 7k. Seems like my problem lies in pacing and not eating. Interestingly, on that note, I know that yesterday I didn't run with enough food in me. Just an even pace made all the difference. Thanks Kaz.
    – saltcod
    Commented Oct 27, 2012 at 12:37
  • If a person can comfortably, regularly run a distance of N, then 2N is doable. Extending distance is not so difficult. Much of the barrier is psychological.
    – Kaz
    Commented Oct 27, 2012 at 17:20

A good general rule is to eat the amount of calories you are burning on the run, 1.5 - 3 hours before hand, or atleast 2/3 of the calories. Once you get fitter and run faster you'll need to consume fewer calories as your metabolism becomes more efficient. Eating low Gi/GL food means you get slower energy release food, pasta is a fairly common one, pittas or oats + yoghurt are also good.

You should also bear in mind how much sleep you've had the night before, and when you are doing the run. The best time of the day to exercise is around 4pm-5pm.


Suddenly running out of energy (the kind you experience) is called a sugar crash. You eat high amounts of sugars (and some carbohydrates) before you go exercising so there is a lot of sugar in your blood. This blocks your body natural energy reserve system (your body fat).

Your body will burn up all the energy in your blood and muscles while you are running and than it is out of energy (because the natural reserves are blocked).

Try this:
1. eat more good fat's in general (fish, nuts, biological meat, coconut oil), this will give you energy without blocking your bodies energy reserve system.
2. eat carbohydrates (quinoa, wild rice and sweet potatoes) at least 1.5 hours before you go on a run.
3. avoid eating 1.5 hours before your run.

The amount of sugar in your blood to disturb the human energy reserve system differs from person to person, thats why some people can handle a plate full of pasta for the race but some can't.

If you got a chance, skip coffee before exercising. It will subtract water from your body just when you need it the most.

  • I agree for the most parts, but very often take coffee - actually a double espresso - just before longer runs (18+ km). It seems to help with my ability to handle the pain at the end of the runs. No, I don't have any studies that back this up :-) Commented Oct 23, 2012 at 17:44
  • Thanks Jesper. I'd never thought about it in terms of sugars before. YOu're likely right. I very often have a bagel+peanut butter, a granola bar, a banana, etc, before I run. All of which is really just sugar, I guess. I suspect hitting my 'red line' on the hills that I run into at about 12 minutes in, in combination with having a sugar crash could be my two issues. Thanks for the tips!
    – saltcod
    Commented Oct 23, 2012 at 18:28
  • You're welcome saltcod. Good luck.
    – Jasper A.
    Commented Oct 24, 2012 at 20:07

I really doubt that you are running out of glycogen (aka "hitting the wall" or "bonking") after 20 minutes of exercise. I'd generally expect most people to go at least an hour on their stored glycogen reserves. It sounds to me like you are just working out too hard.

  • I suspect you're right, Eric. Some combination of the hills I come up to at around 12mins and the 'sugar crash' could be the ticket. I run much, much, much better at night after supper, so proper pacing + a good meal must be the ticket for me.
    – saltcod
    Commented Oct 24, 2012 at 12:57

Dying in the middle of a 5K run is not due to food, unless you ate or drank a bunch just before you ran. (Except, if you're losing weight you may have a calorie deficit and might try eating a normal meal a couple hours before running.) Your body can normally handle the 400-500 calories of effort without any additional food. See what effect a slightly slower pace has.

  • Thanks @xpda. I think I'm going to run on the gym track today just to see. It might give me a good baseline, and b/c there's no hills, it should help with pacing.
    – saltcod
    Commented Oct 25, 2012 at 11:21

Dying on a 5km run? I think you need to run longer.

It sounds to me like your endurance is not very good and you're simply finding it easy to hit your limits. Dying in the middle of the run is something that can happen if you've had a long tiring day or you're running too soon after a previous workout (this goes for any distance if that distance is near the limit of your ability).

I would take 1 day a week and make it your long run day. I would work up to running 10km by increasing the distance you run by 10% a week. Keep the pace as slow as you like.

At the end of that you should find running a 5km fast really easy.

  • Thanks @Sarge! How long should it take me to build to 10k do you think? [In the evenings after a good meal] I can run two 15min sections — doing 5k in about 28 mins. Should building to 10k take me 4 weeks? 8? 6?
    – saltcod
    Commented Oct 25, 2012 at 15:21
  • The add 10% a week thing is key to avoid injury while your body adapts. So 8 weeks or so is pretty safe.
    – Sarge
    Commented Oct 26, 2012 at 16:25

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