What's In Your Bottle? How to Accurately Hydrate and Fuel Yourself for Longer Events
What’s in YOUR bottle? And how’s your Imperial to Metric conversion ability?
If you came of age in the 2000s, you will likely remember the phrase “What’s in your wallet?” even if you can’t remember that the financial services company Capital One originated it. Catchy, punchy, and (probably the most important) slightly judgy, the phrase is routinely cited as one of the great marketing slogans.
“What’s in your bottle?” is…not as universal, because it has an odd target audience of endurance athletes, drunks, and babies. So we probably won’t be seeing this blog post go viral any time soon, but the concept is crucial: do you actually know WHAT is in your bottle? As in, how much fluid do your bottles hold?
I conducted a quick survey of bottles in my pre-ride cabinet (you DO have a pre-ride cabinet, right?) and came up with the following different sizes:
20 oz (591 ml)
22 oz (650 ml)
24 oz (709 ml)
28 oz (828ml)
32 oz (1000 ml)
Yikes. That is a…large variance. Usually when scripting race plans for athletes, we urge something like 5-6 bottles over the course of a 70.3 (start with two on your bike and grab one at every aid station) depending on heat and humidity. For an Ironman we’d double the number and add a little (dehydration is not linear, but…just take my word on that one? This is a blog post, FFS), so maybe 11-13 bottles.
But what if those bottles are different sizes? What if your coach thinks you have 24 oz (709ml) bottles but you have 20 oz (591ml) bottles? Over the course of a 70.3 you’d be ONE BOTTLE SHORT of what your coach wants you to consume! That is significant. Remember, it only takes a 2% loss in body weight via dehydration to see performance losses.
If you weigh 150 lbs, missing that 20 oz of fluid represents a 1% drop in body weight. And you can’t ever remain 100% hydrated, even if you’re fueling correctly. So a misunderstanding about bottle size can lead to 50% of the fluid losses that will lead to performance loss.
Insert facepalm or exploding head emoji here.
So lesson #1 is to measure the fluid content of your bottles and know what goes in them, and have clear conversations with your coach about the bottles you’ll be taking on race day.
The dreaded tapered Gatorade bottle, seen at Ironman events EVERYWHERE, apparently
But…I won’t carry all my own bottles
Yeah, true. Unless it’s a pancake-flat race, we don’t suggest starting your race with more than two bottles (and bike racers with team support, stop twirling your hipster mustaches and smirking about getting all the right-sized bottles with the correct fluid concentration all the time). You’ll have to be grabbing bottles at aid stations as you go along. So now you need to know:
The size and shape of the bottles you’ll get on course (beware the wasp-waisted Gatorate bottle seen above, which was well-known for rattling free from bottle cages seconds after leaving any aid station)
The sodium/carbohydrate concentration of the product in those bottles
So let’s start with an example athlete, Thirsty Thurston, who loses 1000mg of sodium per liter of sweat lost (you can figure out this number by visiting your friendly local Precision Hydration sweat tester) and drops 1.5 liters of sweat per hour at the moment. OK, yikes, now we are in the dreaded Imperial/Metric Triangle of North American beverage sellers. This would be the opportune time to insert a long digression about the time that the United States beverage industry, apparently head-faked by the US government, switched over to the Metric System only to have our legislature get cold feet and stick with Imperial, which is why your alcohol comes in liters instead of, I dunno, drams or something as old-fashioned as “12 stone,” the way the Brits talk about mass, because for some reason they ALSO decided to name their currency for a measure of weight. Good fucking lord. For any other total ADHD nerds out there, just do a quick search for the Metric Conversion Act of 1975 for another detour through US legislative face-palming, if you needed another one.
OK, back on topic! Thurston needs to replace those sodium losses and fluid losses as much as is possible. You can replenish about 75% of your losses, which means that every hour Thurston needs to consume about 1.2l of fluid and 1200mg or sodium. If he’s starting with two bottles that he plans to get through by the end of the first hour, he needs to have two 20 oz/600ml bottles with 600mg of sodium each in them. Thurston grabs two packets of PH1500 and puts one in each bottle (we’ll explain later if you’re scratching your head about that). He’s set for the first hour.
But what about when he starts getting bottles of Gatorade? Or…whatever Ironman is serving at the moment? If you’re luckily racing in Europe, you’ll be getting Precision Hydration and you don’t have to worry about it. If you’re racing in North America, well…you’re gonna have to do some figuring, but ideally the example below will help. A 24 oz bottle (709ml) of Gatorade has about 42g of carbohydrate (good!) and…324mg of sodium. Yikes. Not good. Thurston can hit his carbohydrate and fluid needs by consuming three more bottles of on-course Gatorade, but he’s gonna be almost 750mg of sodium short. That is too short. The fix? Add a 250mg salt pill to every bottle of Gatorade and we’re back on track.
How to batch mix your bottles for a long training day (or race if you can reliably get your own bottles)
Fill a gallon just with water
Mix that fluid to the correct concentration. If you’re using a product like Precision Hydration, remember that a SINGLE packet or tablet of a specific PH product (PH 1500, 1000, or 500) has HALF the amount of sodium listed. Wherefore the odd numbering convention? Well, PH is a sensible metric company who understands bottle sizes, so they create their product for 500ml containers, with the title of the product being for 1l volumes. Head spinning already? It’s not that bad. But the thing to remember is that for every 16 oz/500ml of fluid you’re creating you need one PH packet or tablet. So for this example, that’s EIGHT packets or tablets to make a gallon of fluid.
Distribute that correctly mixed fluid to your bottles
“WHY?” you might be asking. “This seems unnecessarily fiddly.” Well, here’s why. If your bottles are 18, 20, 22, 24, or 28 fl oz you’re going to have to parse annoying quantities of drink mix to those bottles. A 24 oz bottle is 709 ml, or 71% of a liter. Now, if you are also a drug dealer or coffee snob (same thing) you MIGHT have a reliable gram scale kicking around, but you know what strikes ME as fiddly? Weighing out my drink powder by the milligram by emptying it out onto the scale and then distributing those precious little pyramids to individual bottles.
Conclusion
So this might actually be too fiddly for you. That’s fine. We also believe that being too exact about things can create instead of alleviate stress. If you’ve got a good sense of how your body works and what it needs, feel free to ignore all of this. But if you have a big event coming up that you want to nail, why not spend some time figuring this out, because if you get it wrong and blow up, you won’t just be spending time—you’ll be spending money when you have to sign up for the same race next year.