Take a look at the most popular endurance sport drinks, and you'll notice a surprising similarity in ingredients.

There are carbohydrates (usually in the form of sugar), sodium, potassium and sometimes a touch of protein.

You'll notice something else - these drinks are expensive.

It can cost $1.75 or more to fill one 24-ounce water bottle - and you have to drink a bottle an hour to keep up a good flow of nutrients and liquid while you work out.

There's an easy way around the expense: making your own endurance drink. It may not have all the bells and whistles of the top brands, but it should be more than enough for a long ride or run into the mountains. After all, water is the most crucial ingredient, and it's free.

The base for a good endurance drink is carbohydrates. Most manufacturers use sugar, but that is a problem: since its energy is released quickly and is followed by the dreaded sugar crash.

Hammer Nutrition, one of the top makers of endurance sports drinks, uses a complex carbohydrate called maltodextrin that gradually releases its energy. You can buy maltodextrin in 50-pound sacks from a variety of bulk-food and supplement suppliers. Honeyville Grain Inc., which has a store in Rancho Cucamonga, Calif., sells a 50-pound sack for $37.47 (about $60 by mail order).

Next come the electrolytes - salt and potassium. Potassium is easily added using Morton Lite Salt, which contains a mix of potassium and sodium.

The last ingredient is Kool-Aid and sugar to add a light taste and a few extra calories. Remember, this is an endurance drink. It should taste very light.

The final mix tastes slightly tart because of the Kool-Aid. If you like, you can just leave out the Kool-Aid for a more neutral taste. Don't expect the mixture to taste like a commercial sports drink, which typically has much more sugar added.

The ingredients are simple and inexpensive: a carbohydrate such as maltodextrin, electrolytes (salt and potassium) and flavorings, if desired.

Here's my recipe to make about 1 kilogram (2.2 pounds) of powder, enough for 17 24-ounce water bottles.

900 grams maltodextrin

80 grams sugar

2 packs Kool-Aid

5 grams Morton Lite Salt

5 grams regular salt

1. Combine the ingredients in a container with an airtight lid. (It can be messy to make, so be prepared.)

2. Using a digital scale to accurately measure the ingredients, use two 29-gram scoops for each water bottle for a total of about 200 calories per bottle.

Total cost - about 10 cents per 24-ounce water bottle - less than a 10th of what many high-performance drink powders cost.

(c)2012 Los Angeles Times

Distributed by MCT Information Services