What we are trying to achieve here is to prevent more than a 2% drop in body weight caused by fluid loss (about 3 lbs (1.4 kg) of weight loss for 150 (68 kg) pound athlete).
The two main goals of performance hydration is to:

1. Improve calorie absorption by utilizing performance hydration as a “transporter”
2. Maintain blood volume.

Don’t wait until you get thirsty! Remember: better hydration = better performance. Now pull out your calculator, I’ll teach you how to create your ideal hydration solution:

• Carbohydrates: 4-8% solution. To calculate it, divide the grams of carbs (sugar) per serving size by the volume of the serving size (in mL), then multiply by 100 . So let’s say you want to fill your bicycle flask of 500 mL with a 6% solution we will need 30 grams of carbs (sugars).
• Electrolytes. Calculations are easier here: 0.5-0.7 grams of sodium per 1 liter (34 oz) of water. So in the same 500 mL cycling water bottle you will need to add 250-350 milligrams of sodium.

The chart below describes carbohydrates and electrolytes needs for optimal hydration during exercise, based on time. Athletes don’t always need to take extra electrolytes during training or racing. Anything under 75 minutes doesn’t require extra supplementation with sodium pills or salt tablets.

Notes: Glucose can be absorbed around 1g/min and fructose has been shown (when combined with glucose/maltodextrin) to be absorbed at 1.5g/min.

The reason is why you should include calories into your hydration solution is to improve fluid absorption rate. “Fueling” and hydration should be separate from one another, so you’re not trying to get your fuel from your hydration solution. A little bit of sugar works as a transporter to pull the sodium across the intestinal barrier to keep your blood plasma volume up.

Hydration guidelines:

• When creating your ideal performance drink strive for 2:1 ratio of glucose:fructose as it has been shown to improve absorption rate.
• Drink 5-8 oz (150-250 mL) of your solution every 10-15 minutes.
• Train yourself to get used to drink fluids on a schedule while exercising.
• If exercising at higher temperatures or humidity, reduce the intensity to improve the gastric emptying.
• Go with sports drinks over the plain water to minimize the risk of hyponatremia.