While there is no one simple answer to this question, I do have some ideas for you to explore and play with. Ultimately, like nutrient intake, it will be a question of trial-and-error. You will need to go through the "gauntlet" of figuring out proper proportions and what products are right for you.
A tip would be to begin asking various athletes what they recommend, their personal favorite hydration products or beverages, and then give them a try. In addition, you will need to calculate how much hydration will be needed for your given event, and plan accordingly.
Unfortunately, I figured out the hard way, last year, during the "Xterra 10k" trail-run that I had drunk not only too much fluid before the race, but was also carrying way too much liquid in my "Camelbak" pack during the race. It weighted me down, and was unnecessary for me to be carrying that much while I ran.
So what is the "magic formula" for how many ounces to drink per hour, what product to take, etc.? The simple answer is: there is none. There are some guidelines and suggestions I may make, however, as I continue upon my own quest for the "perfect" hydration beverage for me (if there is one).
First and foremost, I am an advocate of getting your fuel from as natural a source(s) as possible, as often as you can. This is sometimes not possible, nor is it practical. For instance, I have 2 "natural" electrolyte replacement beverages that I choose from, and 1 powder-form electrolyte replacement to mix in with my water when needed. Why have this variety? One of the products that I like (will go into more detail below) comes in a glass bottle. It contains apple cider vinegar (ACV). ACV (or any other acidic juice, such as lemon, lime, etc.) should not be put in plastic. The acids "eat away at" or "leach" the plastic, thereby extracting potentially harmful compounds from the plastic into the water, which you then ingest. That's counter-productive. Also, a bunch of glass bottles can add up in weight if you're carrying a heavy pack, running a long-distance, etc. I keep that beverage for when I do "Bikram" yoga, because its easy to transport to the yoga studio. I keep my powder-electrolyte mix in a bag with a scoop (which is light in weight to carry) for backpacking trips, long climbing days, camping, etc.
I also suggest rotating sports beverages of choice (have an "arsenal" of 2-3 to pick from), so that you don't get bored with the same taste. Many people have an aversion to drinking something when they either don't like the taste, or get tired of it. So, think variety, yet consistency in electrolyte profile.
While there is no bullet-proof formula, "Hammer Nutrition" has put out a "guideline" that is fairly good to follow. It, at least, will get you started:
*FLUIDS: 20-25 oz. hourly
*SODIUM CHLORIDE (salt): 300-600 mg. hourly
*CALORIES: 240-280 cal. hourly
Again, if you're interested in a particular sport (ultra-running, Adventure Racing, cycling, etc.) talk to experts, friends, and folks who have put various electrolyte-replacement beverages to the test, and ask them for advice.
Here are my top 3 Favs.:
*"Amy & Brian's Coconut Juice" (this comes in a variety of flavors, & with/without the "pulp"). Check out the following link on this beverage: http://amyandbriannaturals.com/pdf/Coconut_Natures_Sports_Drink.pdf
*BRAGG'S Apple Cider Vinegar Drink. Check out the following link for this beverage: http://bragg.com/products/bragg-organic-apple-cider-vinegar-drink-honey.html
*"Hammer Nutrition" HEED electrolyte-replacement powder drink mix (comes in a variety of flavors). Check out the following link on this beverage: http://www.hammernutrition.com/products/heed-sports-drink.he.html?navcat=fuels-energy-drinks
There are very few over-the-counter sports drink mixes that settle well in my stomach. I've never had a problem with any of the "Hammer Nutrition" products. They pay meticulous attention to using such natural sweeteners in the products as stevia and xylitol, which in turn, keep your blood sugar nice and steady. Products such as "Gatorade," or any of the other myriad sports beverages you purchase at the grocery store cause excessive spikes in blood sugar, thereby setting the body up to "crash" during your event. The body doesn't process rapid jumps in blood-sugar all that well. The mantra to keep in mind is "slow and steady wins the race." Keep your hydration levels and nutrient levels at a nice, consistent "hum" throughout your day, and all will be well. Achieving this may take some time to figure out. Be easy with yourself, and realize that every new product is "on trial" by your gut until it proves itself one way or another. Many trails have been "christened" by athletes as they undergo this process of figuring out what works for their body. Its great if we can avoid this part, and skip to knowing exactly what works for us during long days of activity, but not always possible.
To look more closely at the nutrient/electrolyte profile of each above mentioned beverage I suggested, I recommend going to the links I provided and searching more on the internet about the benefits of each product. A blog post could be done, in and of itself, on the various benefits of raw honey and raw apple cider vinegar.
I hope today's blog was helpful to you, and that it sparked interest for you to undergo the process in finding a good electrolyte/hydration source for your body's needs. ***ENJOY***