Saturday, December 14, 2013

Carbohydrate Math (Or, Why Low-Calorie Sports Drinks Are Useless)

F*** you, Gatorade "G2". You had one job.
Fair warning--this whole post is about sports drinks & their carbohydrate contents & some things that really really piss me off about some road races. So if you don't want to read a whole post just about that, you might want to come back later. Just putting that out there.

If you read regularly you may recall this race report in which I did a spot of quick bitching about the aid stations. Not the logistics or the volunteers; all that was wonderful. My complaint was about the low/no-calorie sports drink.

Before I got into road racing, I spent many years running long distances without eating or drinking anything unless I was going more than 10-15 miles or it was particularly hot, and even then, I only drank water. That was back in the days when I could not have told you how far a marathon was or what pace I was running and had never heard of Gu or Garmins or tempo runs or $12 socks. When I would just throw on a cotton T-shirt & a $6 pair of shorts from Target & run until, I dunno, it seemed like a good idea to stop. In all that time I never had any problems with dehydration, heatstroke, hyponatremia, "bonking," etc. Sure, I'd usually start to feel thirsty at some point, but water fountains were scarce, and putting up with a little discomfort seemed infinitely preferable at the time to the annoyance to carrying a bottle large enough to be of any use.

Apparently, this does not make me a freak of nature. In The New Rules of Marathon & Half-Marathon Nutrition, Matt Fitzgerald opens the chapter on race nutrition thusly:

    The human body is not designed to absorb food or drink while running...When we start to run our body shunts blood flow away from the digestive organs to the muscles, impeding the breakdown & absorption of food...Together, these factors add up to a simple message from our body to our conscious faculties: Do not eat or drink while running. We can disregard this message to some degree without suffering ill effects. But drinking or eating more than a modest amount while running is almost certain to cause debilitating gastrointestinal symptoms.


On the other hand...

    Drinking (and perhaps also eating) a tolerable amount of the right stuff enhances performance in marathons and half marathons. To eat and drink nothing therefore is to needlessly limit one's performance

Which, okay, is a truth I accepted once I got a Garmin & some $12 socks & started entering half marathons & trying to get faster. But even then, I never used gels, only sports drink, and then only in races. I'd read over & over again that our bodies typically store ~2000 Kcalories worth of glycogen, and I needed < 1300 to get through a half (since some of it comes from fat), so really, what was the point? Gu shmu. I carried a little watered-down Gatorade for the electrolytes, but that was all.

I started experimenting with gels when I signed up for my first full, because I can do basic math (26.2 miles => ~2600 Kcal > ~2000 Kcal => even though fat will contribute some calories, more carbs will likely be needed). Based on a few back-of-envelope calculations, I decided on carrying the same 24 oz 50/50 bottle of Gatorade/water as in a half, & then also doing gels at miles 6, 11, 15, 19, & 23, which I think came to around 700-800 Kcal of CHO (that is fancy chemistry-speak for carbohydrate) in all. (2000 + 750 > 2600. Math! :D ) I'd never looked at ingredients lists and my selection criteria was generally limited to whichever brand is the thinnest / most runny (read: easier to swallow), in whichever flavors didn't make me gag.

These were the first gels I ever bought, circa
September 2011. Memories!

Until recently, I had not thought any harder about race hydration / nutrition than that, so getting to those chapters in "The New Rules" was an eye-opener. I still whole-heartedly recommend the whole book (it's pretty short) to anyone actively working on improving their times, but here are a few factoids that I found particularly interesting:

  • We all have different "carb tolerances"--ie, how much CHO can you put in your stomach how quickly without wrecking it. In lab studies most people running at a moderate pace can tolerate 40-50g per hour, although some can tolerate 60g/hour or more, and some rare birds can even tolerate up to 90g/hour. (These tend to be your high-end ultra-runners.) On the other hand, some people have considerably lower tolerances, and some people are really unable to consume anything at all without feeling ill.
  • Generally, as you run faster, your tolerance decreases. (Ie, you probably can't consume CHO as quickly at half marathon pace as you can at marathon or long run pace.)
  • Generally, thinner / more liquidy carbs are tolerated better than thicker ones at faster paces, with sports drink tolerated best. (Ie, the thicker gels that sit just fine in your stomach during a marathon may make you queasy at half marathon pace, & if you struggle with gels, you may do fine with sports drink.)
  • In races shorter than 75 minutes, extra carbs are unlikely to do anything. (This is true whether you're an elite half-marathoner or a newbie walk/jogging a 10K.)
  • In races longer than 75 minutes, 30g of CHO per hour is the smallest "effective dose." (Ie, in studies where runners of similar ability were matched, those who consumed 30g/hour or more consistently outperformed those who consumed less than that, and there was no difference between those who consumed under 30g/hour and those who consumed no carbs at all.)
  • Above 30g/hour, consuming CHO faster seems to predict better performance--if your stomach can tolerate it. (The good news is that many runners find that they can improve their carb tolerance through practice.)
  • There is evidence that a small amount of protein enhances the effect of consuming carbs during an endurance event.

Well. At that point I decided it was maybe time to revisit the subject. I mean if there's some easy fix I could make, I didn't see any reason not to try.

First, clearly my original assumption that extra carbs don't do anything in races shorter than 20 miles was out the window. But according to Fitz, how much CHO should I be shooting for in, say, a half marathon?

I am desperately hoping (fingers crossed) that I'll be back in sub-1:40 shape for Kaiser Half in February, so let's estimate that I'll be out there running for ~1.65 hours (around 1:39). According to Fitzgerald, that means that in order to see any benefit from extra carbs whatsoever, I should aim for 1.65 * 30g = 49.5 (so round to 50g).

When I run with a bottle, I usually fill it with 12 oz water & 12 oz Gatorade. Gatorade contains ~1.7g CHO per oz, so I get 12 oz * 1.7g/oz = 20.4g over the course of the race.Ie, less than half of the minimum effective amount. Occasionally, if it's warm, I might finish the bottle before the end of the race & grab an additional cup or two from an aid station, but that's only maybe 10g more at best.

Without a bottle, I usually grab one or two cups from each aid station. The benefit there is that carrying a bottle obviously sucks. The down sides are 1) you aren't in control of when you get to drink, 2) you never know how much sports drink will be in the cup, and 3) you don't necessarily know what will be in the cup.

Which brings me back to Berkeley a few weeks back. I'd been hoping to try some of this stuff out, including not carrying a bottle (which Fitz suggests entirely cancels out any extra benefit you get from the carbs), so I went to the website to find out what sports drink they were pouring. Under "Water and Aid Stations" the page read only "More information coming soon!" As that was the night before the race, I did not have a lot of hope that that was the case.

(I totally get that this was partly my fault. I should have checked earlier & emailed someone.)

My concern wasn't because of some diva-ish preference for this sports drink over that one or some miniscule difference in the amount of carbs in Gatorade vs Cytomax vs whatever. My concern was that I've been to several races lately where the sports drink on the course doesn't contain any carbs at all--just electrolytes. And if that was the case, I was just going to carry my bottle of pure Gatorade and a gel & see how I did with that amount of CHO.

I asked a volunteer at the info booth but all she could tell me was the flavor ("berry," if you're curious). A few minutes later I heard the announcer mention the name of the sports drink sponsor but didn't quite catch it, so I went up to him with my most sheepish, I-know-I'm-a-big-dork look & was all like, "This is probably a really weird question, but..."

He said it was something called Vega, which I had never heard of. At that point I guessed he already thought I was probably the weirdest person there so it couldn't hurt to get even nerdier about the whole thing.

"What I'm really trying to figure out is if it has calories in it. Like, y'know. Carbs. Like, for running."

He gave me kind of a duh look. "Oh, I'm sure it does," he nodded. "I mean it's like Gatorade, you know? Sugar and electrolytes and stuff. It must, right?"

Confidence = not inspired. But thanks for trying, announcer man.

"I think there are some samples over there." He gestured toward one of the info booths. I did not find any samples, but I thought, Surely he's right? Surely a real, actual race run by an experienced group like SFM will not be using a low/no calorie sports drink in a half marathon?

So I left my bottle in the car. And I knew the second I took a swig at the first aid station that I had been betrayed, that there were no calories here to be had, at least not enough to be of any use. (Also the weird fake-sugar flavor was nauseating.)

Out of curiosity, I looked it up after the race. Sure enough: "A natural, alkaline-forming drink mix, free from sugar and artificial sweeteners, Vega Sport Electrolyte Hydrator is formulated with all the essential electrolytes your body needs to stay hydrated during workouts.* With zero calories per serving, Electrolyte Hydrator tastes great, so you can sip it not just during your workout, but throughout the day.

*These statements have not been evaluated by the Food and Drug Administration."


No carbs = not appropriate for supporting endurance athletes through an endurance event. Period.

So yeah. Lately it seems that relying on aid stations means you may not get any liquid carbs at all. Which is NBD I guess if you're just out to have fun or do a social event with friends. But if Fitzgerald is right, it does seem to mean that you can't expect to have your best possible race, particularly at a half marathon where the pace is faster & thicker, denser carb sources like gels may not be tolerated as well (or at all) for a lot of people.

I don't know yet what the sports drink will be at Kaiser, but I'm hoping it will be something with calories so I can experiment with getting the right amount of carbs while also not carrying a bottle. If that's the case, I think I may try something like the following & see how it goes:

    Pre-race: Accel gel w/ protein -> 18g
    Mile 4: Accel gel w/ protein -> 18g
    Mile 6.2: 1 cup sports drink (~3 oz?)-> ~5g

    ***1 hour mark = 41g***

    Mile 8: Accel gel w/ protein -> 18g
    Mile 8.4: 1 cup sports drink (~3 oz?)-> ~5g
    Mile 11.1: 1 cup sports drink (~3 oz?)-> ~5g

    ***Total = 69g hehehehe***

This will be massively, MASSIVELY many more carbs than I've ever consumed during a half marathon, but still on the conservative side in terms of what Fitzgerald says most runners can tolerate. Between now and then, I need to use some of my long runs to try to figure out just how my tolerance stacks up.

So my, real, actual questions for you (ie not fake/obvious ones designed to generate more blog traffic, eff that noise, I am so sick of it) are:

1) Are you this nit-picky about how many carbs you consume and when and how fast, or do you just, y'know, knock back a gel or two when it feels right? How has that worked out for you?

2) Thoughts re: carb tolerance? I've never felt sick from gels / sports drink while running, but as noted, my intake is apparently pretty anemic by Fitzgerald's standards.


  1. This is a big pet peeve of mine, too. Honestly, I don't understand the concept behind an electrolyte drink without calories. If I'm losing electrolytes, I'm certainly in need of calories, too. A short run wouldn't deplete my electrolytes! Yet races - distance races, mind you! - cheerily serve low cal/no cal beverages. So dumb. I haven't ever done any calorie math for races, but I did kind of nail down a balance between enough carbs and a calm stomach: Four gels for a marathon, split into half-packets, plus alternating sports drink and water when I stop (switch to water only if nausea occurs). I have a sensitive stomach, so it can be hard for me to keep gels down, and honestly I often throw away an unfinished pack. I'm looking forward to reading your results for the upcoming half - if the math works, I'll jump on that bandwagon in no time! Thanks for another insightful, useful post. I always appreciate your topics.

    1. You're welcome! I'll definitely report back on how my Kaiser plan works out. :)

  2. I am exacting about my gel intake- I do one every 5 miles during marathons and halfs too. I did 1/4 miles when I was slower. I don't know why. I haven't actually done the math until now, but that means I'm only getting about 20g every 40some minutes. I also drink whatever the sports drink is at the race, usually every 2 miles or so. That's worked for me so far, but it sounds like I might be undershooting it a little bit according to the book. Super lame about the lack of decent beverage at your race.

    1. Hm, depending on the sports drink, sounds like you *might* be getting to the 30g / hour mark, but definitely right on the border. I'm definitely looking forward to seeing how more carbs work out for me. I never *feel* like I'm under-doing it, but it sounds like I wouldn't necessarily notice it.

  3. Actually - I'm one of those unfortunate freaks who has trouble with sports drinks. Throwing up the Pocari Sweat during a race is no fun. Plus if you're not accustomed to drinking during shorter races I'd worry about the volume! I've had drinks slosh around in my stomach. Completely distracting! I tend to rely on a combination of beans/ shot bloks, a bottle of electrolyte drink, and water. Still experimenting though, considering my cramping at this year's marathon.

    1. Ah, boo! Yep, probably trial & error is the way to go. Good luck!

  4. No calorie drinks during races are insane. There's no point!

    I've never eaten or drank much during running races, because it's just so logistically hard during running races and hard on your stomach. But, triathlon I eat regularly, usually gels or chomps and drink. I found, though, contrary to the current trendy nutrition, that I massively prefer to drink most of my calories because it's so much easier on my stomach. BUT, then you have to remember to drink enough water too or you get dehydrated. So.

    And, yes, from my recollection Kaiser has actual sports drink, but not a billion aid stations.

    1. Agree--I'm *terrible* at managing gels while I'm running, but I'm not sure I could get enough carbs from sports drink alone without getting to the sloshy stomach point (which is just never a good thing). I know some people who have had success mixing gels into water / sports drink, but that's only really an option if you can drop your own bottles or are carrying it with you.

      Yay! I ran KP back in '10 but I don't remember much about it, so that's good to know about the sports drink.

  5. I'm not sure if my comments are useful as you're a much stronger runner than I am. However if it's helpful, I TRY to take 3 gels during a half (at 4,8 and 10). Having said that, I've never been able to take that third one - my body just can't face it. So I take 2. I've never tried sports drinks at all during a race - I tend to carry a handheld filled with diluted pure apple juice. I find the taste perfect and hope that the natural sugars will help a little. I know it's not scientific but it's worked for me. I think Nuun is disgusting apart from the All Day flavours, which I really like as they're less sweet, but I tend to use them for hydrating afterwards/beforehand rather than during a race.

    1. Hey, it's all about what works for you! If you get any gels down at all you're already of me....

  6. I find this subject *fascinating* lately and I would love to take any reading suggestions from you! I remember Nike (...I think?) getting crap for having only Nuun on the course, which was the first time I'd really thought about this issue. I train with Nuun, so I guess I didn't fully see what the big deal was at the time, BUT I also eat most of my carbs -- plus, I would have expected the opposite in terms of aid station stocking (e.g. aid stations would have traditional sports drinks, and if I wanted something else, I'd be bringing it).

    With the exception of Sport Beans, which gave me the WORST stomach cramps I've ever had (likely because I didn't take them with enough water, but it was so bad that I have no particular desire to repeat the experiment), I can handle pretty much any gel, block, etc., as long as I like the flavor. And I'm the opposite of you, texture-wise: the thicker and more frosting-like, the better for me. I honestly have always chalked this up to personal preference, which is generally toward eating whenever possible (in life).

    However. This year, I started to wonder if my body really just tolerates solid better than liquid carbs. Here's the key to my theory: There is a point in almost every race where my brain goes "Gatorade! Gatorade!" When I actually drink the Gatorade, I almost instantly get a stomach cramp. If I answer the Gatorade call with a sip of Nuun/water and a shot block or something, though, I'm fine.

    Because of this, I've been pretty fascinated by the science of drinks like Skratch and Osmo lately ( I have found Skratch in particular to be a perfect happy medium for me when I'm biking on a training day: It's 40 calories per serving, with 10G carbs, which gives me wiggle room to eat a damn buffet but keeps me a little more ... stable, I guess, than Nuun/water only. I race triathlon with something a little carbier/more caloric (usually Rocktane), but it tastes syrupy enough to me that I'm usually mixing it with more water/not drinking all of it and maybe not getting the full benefit. Skratch has the added plus of tasting goddamned delicious to me. (It's like my sense memory of Kool-Aid, which is mostly funny because I think actual Kool-Aid would taste nasty to me now.)

    Then again ... most of my training these days is for triathlons/longer endurance events where I'm just simply not going THAT fast, and I have plenty of time on the bike to process food, so maybe if I suddenly became super speedy or were training for only running events, this would all change?

    1. I actually like Nuun pretty well, & I used to take it on short runs all the time just because it was more entertaining than water. But yeah, I am pretty amused any time anyone talks about how they "fuel" with Nuun. No. No you don't.

      We'll see how I do with gels at HM pace. I had two at Berkeley (one before & one around mile 6), but I was running at marathon pace so I would've been surprised if I'd had any trouble.

      I will have to look into this Skratch & Osmo stuff. Interesting!

  7. When I read your title, I was like, AMEN!!! YES!!!! I've only recently discovered how much I depend on sports drink to supplement my gels and chews. Like Cathryn, I can't ever seem to stomach that 3rd gel, but if I have my handheld with Cytomax in it, I'm definitely okay with sipping liquid every 5 minutes or so. And both my half marathon and marathon PRs were run with my trusty handheld bottle of Cytomax, whereas I've bonked pretty badly in all of my other races recently when I've gone without it.

    I've also volunteered at aid stations where they're serving no calorie electrolyte drink. No only did the drink lack carbs, but it tasted really gross. I actually tried to convince people not to drink it.

    1. Lol, that's awesome. I always give people the side-eye when I hear them yelling about "electrolytes."