Hydration is a key factor in optimal exercise performance. Even a 2% loss in fluid can impair performance and increase your risk of heat stroke. An important thing to consider when rehydrating is total electrolyte and carbohydrate consumption. Many sports drinks and the products listed below contain electrolytes & carbohydrates and so do many gels and chews. When you are choosing how you want to take in nutrition be mindful that if you are drinking Tailwind you may not also need a Gu or if you are taking in a gel with water, you may not need to have a sports drink.
Tailwind is a carbohydrate & electrolyte supplement powder. There are caffeinated and non-caffeinated options. With 130 calories per 16oz serving, Tailwind is thought of as “the complete package” for your hydration, carbohydrate and electrolyte needs.
Skratch is a carbohydrate & electrolyte supplement powder. With 80 calories per 16oz serving it's lighter on the carbohydrate than Tailwind. Depending on the flavor, it's not uncommon to see raspberry seeds floating at the bottom of your bottle as they use real fruit for flavor. They also make a caffeinated green tea and lemon flavor which is great served hot.
Both Skratch and Tailwind are available in large bags and single use pouches which are great for testing out different flavors and seeing what works best for you. You should avoid trying a new nutrition product on race day as you may not know how it will affect you. Make sure to mix the powders with the recommended amount of water to avoid dumping syndrome (cramps, dizziness, light headed feeling, diarrhea- basically as bad as dumping syndrome sounds) which can happen when the carbohydrate to water ratio is off.
Nuun is an electrolyte supplement that contains only 10 calories per serving. This is a great thing to think of for all day hydration or for when you don't need carbohydrates to refuel. They come in effervescent tablets in many great flavors and some also include caffeine for an added boost. A few of us here may even be known to add half a tablet to our beer for a Nuun Shandy...
Nuun also makes a new electrolyte & carbohydrate drink mix called Nuun Performance. Available in 2 flavors, blueberry-strawberry and orange-mango, it utilizes dried fruit powder for natural flavor.