Feeling sick/faint after running long distances
September 13, 2013 10:28 AM   Subscribe

I am training for my first marathon, and my recent long runs have led to me feeling like I'm going to faint right afterwards. Looking for advice about what to eat before/during a long run.

I've been a runner for about a year and a half, and I've run several half-marathons without any issues. However, I'm training for my first full marathon, and the two times that I have run over 30 km I have felt extremely weak immediately afterwards.

The first time was right after a 30 km race. I was fueling with Clif Shot Blocks throughout the race, which I have used in many long runs without any issues. (I have used a variety of gels and gummy blocks in long runs, and they have never given me problems in the past.) I was quite tired by the finish line since it was my longest run to date, but I felt okay for the first 10-15 minutes after stopping. Then suddenly I felt extremely weak and nauseous, and my vision was getting blurry and pixelated. I almost passed out but I was able to lean on a friend until she could take me to a bench to sit down. I was very pale and shaky. I drank a coke and started to feel better, but still wasn't able to eat much solid food until the next morning.

That was about a month ago, and my long runs after that were only up to about 28K until last week. After those long runs I was tired but still fine... no faintness or trouble eating afterwards.

Then last weekend, I ran 33K for the first time. I took only two gels with me - I had one after about 1 hour, and then the other at about 2 hours. I felt okay until the last 10 minutes or so, when I was starting to feel very weak (but not faint). Once I stopped running, however, within about 5 minutes I thought I was going to pass out. My vision became cloudy again and I was very pale. I sat down for a few minutes, then had a coke and started to feel better.

I am a little worried about this trend. The first time I felt this way, after the race, I thought it was because I was pushing myself too much. I was running at about a 5:27 min/km pace since I wanted a good time. The second time, however, I was taking it easy because it was a long training run - running about a 6 min/km pace. So now I'm a little confused about what strategy to take for my long runs (and eventual race). I eat breakfast (oatmeal or Cheerios) about 1.5 hours before running, and always bring gels/gummies with me for the run itself. I hydrate properly during the run.

I searched online and found conflicting results. It sounds like it could be "reactive hypoglycemia". But I'm not sure if that means I should eat more gels during a long run, or whether that will lead to too much insulin release which will actually lower my blood sugar instead of raising it. Do I need to change my breakfast instead? I could add protein to the breakfast to even out my blood sugar (peanut butter or eggs). Or should I bring beef jerky with me on the run to eat instead of/in addition to my gels?

Any advice or personal experiences are appreciated.
posted by barnoley to Health & Fitness (20 answers total) 5 users marked this as a favorite
OK, a few things pop out to me (about to run my 2nd full marathon, but have run more than 40 races in the past 3.5 years).

1. You're waiting too long after breakfast to run. I never start my run any more than 45 minutes or so after I've eaten.

2. One gel an hour is probably not enough. I'm not great at mile/k conversion, but I have a gel every 45 minutes or so.

3. What's your hydration plan like? Not just while you're running but all week long? Dehydration can factor big time into what you're feeling, and you need to be drinking as much water all week long as you can.

4. You're almost definitely running too fast. Long runs should not be 30 seconds off of your "good time" pace. They should be 60-90 seconds per mile slower than your easy pace.
posted by roomthreeseventeen at 10:39 AM on September 13, 2013 [5 favorites]

I have no direct experience at those distances, but what you're describing sounds like the wall.

And as a sidebar training recommendation -- I've been training with a heart rate monitor this summer for my long runs (only 11-15 miles) and combining that with a low heart rate target has made these runs way less painful than they were last year when I was running them much faster.
posted by garlic at 10:42 AM on September 13, 2013 [1 favorite]

Best answer: What has the weather been like? This could as likely be a heat issue as a fueling issue-- whenever I have felt that way in the past (extremely weak, blurred vision) it was due to heat.

The first thing I would try is increasing the number of calories you are taking on runs. I would try doing one every 45 minutes- 50 minutes instead of 1 per hour and see if that helps. Everyone has different calorie needs on runs and during a 33K run you're burning around 1500-2000 calories. You might just need to replace 300 or 400 instead of 200 of those calories during the run.

What is happening around the 30K mark is that you are coming close to using up the last of your body's stored glycogen. The gels aren't going to have an effect on your blood sugar, they are used as fuel almost instantly (instead of your body's glycogen reserves). If you can keep your body from using the last of its glycogen reserves, you should be able to keep from feeling so bad after a run.

I just finished Matt Fitzgerald's "The New Rules of Marathon and Half Marathon Nutrition" and it goes pretty in-depth into this stuff. His recommendation is around 60g/carbs per hour during a race if your stomach can tolerate it-- That's quite a lot of carbs. I think each standard gel has about 20 carbs and a packet of shot blocks has about 40.
posted by matcha action at 10:46 AM on September 13, 2013

When I have this problem, its because I'm dehydrated and and don't cool down well enough so my blood pressure crashes. That said, you are running much faster than I do, so perhaps that is part of it. I think you need to down the gels more often, for a three hour run I use at least four. My belt holds five, so I fill it up just in case. I also stash bottles of water in the bushes along my path (this sounds weirder than it is) so I am much more hydrated than I used to be.
posted by Nickel Pickle at 10:46 AM on September 13, 2013

Best answer: I'd look into two changes to your routine. First, ensure that you are remaining adequately hydrated during your run, probably a mix of sports drink and water to keep up your electrolytes. Second, I have much better results when I fuel with a mixture of carbs and proteins, so I'd look for a gel or block that also supplies protein with the carb. I have no idea what the science behind it is, but I find that I have much less of a post-run crash than when I only consume carbs. I'd also add some protein to your pre-race fueling and I think eating 90 minutes or more before you start is a good thing. I also think that if you are going to fuel with pretty much all sugars, once per hour is not nearly enough to avoid a pronounced crash, which is exactly what you are experiencing. In review, mix in protein both before and during, make sure you adequately hydrating and fuel more often. If you are experiencing exercise induced hypoglycemia to such an extent that you get dizzy, your performance is almost certainly suffering during the run as well.
posted by Lame_username at 10:53 AM on September 13, 2013 [1 favorite]

A fellow runner here (one marathon and a bunch of halves on my running CV)- what is your nutrition like during the week and especially the day before the run? This might be your body's way of telling you to fuel more in general, not just during the actual run. Are you eating enough carbohydrates and eating enough to support your running? Asking because the only time I experienced something similar to what you describing is when I went into the long run after a couple of days of not eating enough food because my stomach was playing up. The other thing which your body also seems to be telling you is to experiment with having some nutrition after the run - you described two instances when you perked up after a hit of sugary drink. A lot of it is trial and error, we are all an experiment of one. Final recommendation is to see a sports dietician - I have consulted one in the past and found it really useful.
posted by coffee_monster at 10:53 AM on September 13, 2013 [1 favorite]

For my American brethren, first race was 18.6 miles at 8:50 per mile and the training run was 20.5 miles at a 9:40 pace.
posted by Lame_username at 11:00 AM on September 13, 2013 [4 favorites]

Thank you, lame_username. Yep, too fast on the long run.
posted by roomthreeseventeen at 11:03 AM on September 13, 2013

Shot in the dark, but it sounds like you maybe drink a lot of coke? Perhaps cut out the caffeine for a couple of weeks and see if that helps.
posted by Grither at 11:08 AM on September 13, 2013

Best answer: About midway through a long run I need some protein and fat. I know that no one recommends that, but I'm me and not a textbook.

I take along Justin's honey peanut butter packs. They're a little gummy so I warm it up in my pocket or bra. It's just so friggin' satisfying that I can keep running and running.
posted by 26.2 at 12:25 PM on September 13, 2013 [1 favorite]

Response by poster: Thank you for the great responses so far. Just to clear up the coke issue - I never drink coke normally... I am a strictly water drinker for the the most part. My husband is the one who drinks a lot of coke so it is always available in our house.

But that is a good point with the general nutrition - I am pretty small (around 5'3", 101 pounds), and while I do eat a lot in general, it is not really all that healthy. I will focus on getting a more well-rounded diet, and perhaps a large dinner the night before a long run. Also I'll increase my water intake the day before.

I will try using more gels for this week's long run. I was just afraid that it would cause my blood sugar to spike and then crash. I did use the equivalent of a gel every 45 minutes during the 30K race, but I was afraid that contributed to the crash that time and so I reduced my gels for the 33K run. I will try to have a breakfast with more protein this week.

As for my pace... I will try to slow down in my training runs. I honestly find it very difficult to run slower than 6 min/km. Using the McMillan Running calculator and my race times for 5K/10K races, it recommends long runs at 5:20 to 6:08 min/km.
posted by barnoley at 12:31 PM on September 13, 2013

(I am not a doctor, etc.) But I don't think this is reactionary hypoglycemia. Why do I say that? Because I have reactionary hypoglycemia/with other low blood sugar things. I think you have overall - exercise caused - low blood sugar (hypoglycemia, or borderline hypoglycemia.)

Now, if you had a big pancake breakfast and experienced the sugar crash within an hour (which is what you had, it's scary as hell, right?) then I would say you may have reactionary hypoglycemia.

Reactionary means that your blood sugar goes too high, too fast, due to the glycemic index of the food you eat. (For me this includes white bread, any rice, pasta, etc.) These foods with a high glycemic index send your blood sugar up quickly, then you body goes "Woah! That ain't right!" and overcompensates. (For me it would look something like a blood sugar level of around 150 to 170, then shooting down to less than 90 within MINUTES not hours. Normal range is about 80 to 140 ish.) In fact, white flour foods have a higher glycemic index than sugar. Also, I don't think the gels even have enough carbs to even give me a sugar crash if I had just one of them.

So, because these reactions are happening after a long run and not a lot of food, I suspect you are not getting enough food, protein, and sugars during your run. So, what do you do?

I suggest getting to an internal medicine doctor and have them give you a glucose meter (glucometer.) I got mine for free and then a Rx for testing strips and lancets. You can get them over the counter just about anywhere that has a pharmacy, and online but it will be expensive without a Rx. You also want to have a doctor help explain sugar levels to you.

They will probably want you to check and track your blood sugar along with the foods you eat and symptoms during the day, and especially during and after your run. I suspect that it will show that you aren't getting enough sugars and are exerting too much energy during the run, hence the sugar crash.

So, what does low blood sugar mean? You will probably want to meet with a dietitian, but if it's low blood sugar because you aren't getting enough foods, then that's pretty easy. You increase your carbs and sugars during your run to keep them level and not have a crash afterward.

If it's reactionary it's a little more complex. I have to avoid foods and really keep track of my proteins and fats versus carbs.

Memail me if you have questions, but I strongly encourage you to pick up a glucometer over the counter and even check yourself if you can't get to a doctor quickly. (However I also strongly encourage you to get to a doctor, low blood sugar can be life threatening.)
posted by Crystalinne at 12:33 PM on September 13, 2013

Best answer: I suspect hydration isn't the issue; as others have said, it sounds like the wall (or as cyclists say, bonking). You've used up your muscle and liver glycogen and you're not putting enough glucose into your bloodstream to power your brain. In addition to eating more, you might try modified carbohydrate loading (without depletion) before the event, which can result in more glycogen being stored.

For more detail, I suggest the chapters on the physiology of running in Tim Noakes's Lore of Running, even though the 4th edition is now a little long in the tooth.
posted by brianogilvie at 1:19 PM on September 13, 2013

Response by poster: Crystalinne, thanks for the clarification about reactionary hypoglycemia. I guess I was just confused. I don't normally have a problem with low blood sugar when not exercising, unless I don't eat often enough. (I do need to eat every 3 hours or so to avoid feeling lightheaded, but I think that is pretty common.)

I am hoping that increasing my gel intake, as well as having a protein-filled breakfast, will help. I would like to bring some sort of snack during the run that has protein...but I don't know of any available in Canada. Those Justin peanut butter snacks mentioned above sound good but I have never seen those around here. If just adding more gels does not help, then I will try some beef jerky next time.

Thanks again for the answers so far. I feel a bit more confident about the gel situation after hearing that this sounds typical of "the wall" or "bonking". I was a little skeptical before, because a lot of my running friends do not need gels as often as every 45 minutes, and they have been encouraging me to wait until 1 hour for my first gel. (I think maybe because I'm a little bit small my muscles do not hold as much glycogen as other people? Especially because I haven't been running for long enough to build bigger muscles yet?)

I don't think I have a 30K or more run scheduled for a couple more weeks, but I will update this thread after I my next very long run.
posted by barnoley at 4:28 PM on September 13, 2013

Recently I had been a little frustrated that exercising only seemed to make me more tired, I wasn't building endurance at all. Flash forward to a couple of Fridays ago, when I was running errands on a hot day and I passed out in a gas station. They took me to the ER, and I found out I'm currently anemic. My BP was very, very low, and I felt a lot like what you describe.

It's something to consider as a possibility. I don't know anything about running, but I think you might want to see your doctor and have a little bloodwork done, just to make sure there isn't something weird going on.
posted by Ursula Hitler at 4:30 PM on September 13, 2013

Seeing your follow-up-

Yes, your small size might be one factor in you not being able to access as much stored glycogen as your runner friends-- One formula for trying to estimate how much glycogen you can draw on in a long-distance race involves estimating the mass of your legs. Glycogen is stored mostly in your liver and your leg muscles, larger leg muscles can store more glycogen.

The other factor is that the percentage of calories you burn coming from carbohydrates (as opposed to from fat) is quite variable. Some of the factors include the pace you're running (the slower you go compared to your maximum pace, the more fat you burn), how well-trained you are (the better trained you are, the better you'll be able to use stored fat as opposed to stored carbs), your diet (there is a theory that people on higher-fat or low-carb diets will burn a higher percentage of fat, partly out of necessity). Your running friends aren't necessarily wrong in telling you to wait an hour for your first gel-- they've probably just been running a little bit longer and have better developed the ability to rely on stored fat for fuel.

If you're running as long as 33 K now, your marathon is probably relatively soon. Given that, I would encourage you to fuel appropriately for your current needs, even if that means taking in a few more gels than your friends do. In the future, if you run another long-distance race, it might be helpful to alternate 'fasted' long runs (run first thing in the morning, no breakfast, no gels/sport drink before or during the run-- when I do this I do bring a gel with me, just in case) with normal long runs where you fuel appropriately. I don't know if there's specific science backing this up, but there is a theory that doing some of your long runs fasted increases your body's preference for stored fat over glycogen, so that over time you become less reliant on gels, and less likely to hit the wall.
posted by matcha action at 6:06 PM on September 13, 2013

Best answer:
I would like to bring some sort of snack during the run that has protein...but I don't know of any available in Canada
Many of the sports gels on the market contain a mixture of carb and protein. I actually first bought Accel gels there! I went to a runner's nutrition clinic recently where they suggested that once you start to take on gels, you should keep taking them every 20-30 minutes to avoid a blood sugar crash, which sounds like what is happening to you. Personally, I wait 90 minutes and take them every 30 minutes thereafter. My wife likes to start at 60 minutes like you.
posted by Lame_username at 9:11 AM on September 16, 2013

Response by poster: Lame_username, that's good to hear - I have not noticed Accel gels on the shelf before, but I'll look this week when I go gel shopping.

I just wanted to update with my experience this week. I had a shorter long run (around 24K), however I changed my breakfast to a large whole wheat bagel with peanut butter around 1 hour before the run. Wow, what a difference! I felt a million times better. It was actually shocking how much better I felt throughout. I know that this was a shorter run, but compared to how I've been feeling during runs of this length in the past... well, it was like night and day. I didn't even feel like I needed a gel at 1 hour, but I forced myself at that time and then again after another 45 minutes. There was no lightheadedness or weakness at any point, and afterwards I only felt some soreness in my legs.

So, it looks like I just wasn't fueling enough before a long run. I had really thought that Cheerios was an appropriate breakfast... but it looks like I need a lot more carbs and protein.
posted by barnoley at 9:36 AM on September 16, 2013

Response by poster: Final update: long run of 32K yesterday, ate my bagel with peanut butter 1 hour before, used gels every 45 minutes...and I felt fine at the end. Well, pretty tired actually, but there was no risk of fainting.

My race is 3 weeks away, so I feel a lot better now. My plan for the race is to up the gels to every 30 minutes to compensate for the increased speed/intensity, and stick with the bagel/peanut butter combo for breakfast.

Thanks again for all the advice, it was very helpful.
posted by barnoley at 12:11 PM on September 30, 2013 [1 favorite]

Response by poster: Final final update (the last one, I swear!): ran my marathon on Sunday, finished in 3:55, felt great the whole way through!

(Well, I didn't feel great from 28K to 38K...but by the finish line I was actually feeling fantastic. Took my first gel at 45 minutes, and additional ones every 25-30 minutes. Even though that was WAY more frequent than all my friends and acquaintances, it was just what I needed. And now I can call myself a marathoner!)
posted by barnoley at 12:22 PM on October 24, 2013 [3 favorites]

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