If you want to skip all the science and the explanation of how I came to the formulation, you can download an excel spreadsheet that helps you create a recipe for this sport drink.
I was initially motivated by convenience. I cycle long distances. When out for a long ride, Fondo, or the like, being at the mercy of what sport drink is served up at an aid station or available at a convenience store is challenging because you don’t know how your body will react. Similarly, trying to take in an appropriate amount of carbohydrate and electrolytes is a massive struggle when you’re constantly changing your nutrition.
I needed a powder that I could just mix with any available water source. That way I could pack as much as I wanted and not cart bottle after bottle of liquid around, but still maintain consistency in my nutrition. I set out to find a good powder to use and before long found that most ready-made powders were: absurdly expensive, terrible-tasting, and/or inconvenient to portion out and carry. Time to break out the chemistry textbook and make my own.
Skip to the “Make it in Bulk” section if you don’t get the same kick out of the details that I do
I didn’t want to just clone something on the market, I wanted to provide my body with the fuel it needs while creating something tasty and convenient to carry. Bonus points if it didn’t break the bank. I’d be looking for:
- Readily-available ingredients (Amazon helps a great deal here)
- Slightly hypotonic. We’ll look for around 193mmol/kg
- Replace sufficient amounts of the key electrolytes
- 1L human sweat contains 0.02g Calcium, 0.05g Magnesium, 1.15g Sodium, 0.23g Potassium, and 1.48g Chloride.
- Provide around 100 calories per 24oz bottle so I can supplement with gels or bars to get to the 120-360 calories/hr recommended
- Pack in to an easy-to-transport, water-tight container
- Taste good
- Bonus: Inexpensive
I’m using Polar bottles at 24oz each, and consume around one bottle per hour (more or less based on conditions). Since two bottles is 48oz, I’m going to aim to replace the electrolytes lost in 1L of sweat across the two bottles (remember, we’re trying to be hypotonic). Since we’re losing water to respiration as well as perspiration, this seems like a reasonable place to start, but also a good place to experiment. What is the ratio of respired water vapor to perspired water during endurance exercise? Is there even a ratio that’s applicable across a wide enough range of conditions?
First, we select quantities of our electrolyte ingredients to yield the desired quantities of each ion. Recall that we have to break the salts apart according to their atomic weight to get the contribution of each electrolyte.
Now we add our carbohydrate. Recall we’re looking for around 100 calories per hour, or 200 calories per 2-bottle batch. Ideally we want around 52g of carbohydrates. We’ll use table sugar (1:1 ratio of glucose:fructose) and maltodextrin (entirely glucose and slower digesting) for our carbohydrate. The ratio here is selected as a midpoint between the research quoted by Pro4mance showing we want a 2:1 ratio of glucose to fructose and this research out of Massey University showing a 5:4 ratio is beneficial. We’ll be using a 3:2 ratio and 59g (228 calories) of carbohydrate as our starting point.
Putting it All Together
Now, we look up against an osmolality table for our various components to get the number of mmoles of each in our batch:
And since a batch is 48floz or 1.36kg, we can calculate our mmoles/kg (or our osmolality).
This yields an osmolality very close to our target of 193mmol/kg.
The best flavoring I’ve found, taking in to account convenience, flavor, and ingredients that won’t throw off the delicate balance we’ve created above, is Kool-Aid packets. They come unsweetened, so they simply add a little flavor and color without adding more electrolytes or significantly altering the osmolality. I find 1.85g (we’ll see how we get there in a moment when we get to making in bulk) creates a pleasant flavor, but this is definitely personal preference. One bonus great thing about using Kool-Aid is the variety of flavor options. I like the Strawberry-Kiwi, myself.
Add in the Kool-Aid and we’re just shy of 66g for two bottles, or 33g per bottle. It just so happens that an old 35mm film canister will hold 33g of this powder comfortably. They’re water-tight and easy to transport in a jersey pocket. One more goal accomplished!
Make it in Bulk
If we make 26 bottles worth of powder, the quantities get to be numbers we can measure.
* 5 packets
Bonus: Make it Inexpensively
Using my own local sources for ingredients (and running to Amazon for the Maltodextrin and Citrates as well as 96-packs of Kool-Aid packets), I calculate a per-bottle cost of $0.26.
I’ve been using this mix for the last two seasons (as of 2016), and I can say without a doubt, it’s achieved everything I set out to accomplish. I carry enough portions for my ride in film containers and add it to my bottles when I refill. A surprising correlation is that I haven’t had a single leg cramp since I began using this mix, and while the singular of data is anecdote, I’m quite pleased. I hope you have the same success.