New fitness waters

Adequate fluid intake important

"Many athletes experience alterations in taste preferences during heavy exercise and won't drink adequate fluid if it is water alone," says Lona Sandon, assistant professor of clinical nutrition at University of Texas Southwestern Medical Center at Dallas. "The sweet or salty taste of these fitness waters helps them to drink adequate fluids."

The most beneficial nutrients added to most fitness waters include carbohydrate, sodium and potassium.

"The added carbohydrates help maintain the glycogen, or energy stores in the muscle," she says. "Someone who exercises daily must constantly replace these muscle glycogen stores. The added sodium and potassium work mainly in the body to maintain water balance within the body's cells to prevent dehydration."

But not all fitness waters are created equal, Sandon says.

"You must read the label to determine which will be best for your active lifestyle. Some brands may only contain potassium and no carbohydrate or calories. If electrolyte and water replacement is all you need after a short workout then it is OK, but if it is endurance and energy you are looking for, this will simply not do."

Popular fitness waters

Propel

Reebok Fitness Water

Glaceau

Hansen's e20 Energy Water

Essentia

Elements Enhanced Water

VitaRain