dehydration

Fresh water quenches thirst almost instantly, but salt water doesn't. New research shows how cells in the gut and on the tongue help the brain keep just the right concentration of salt in our bodies.

Does exercise recovery work? Science writer Christie Aschwanden examines the physiology and effectiveness of sports drinks, protein powders and other products and services in her new book, Good to Go.

Dehydration has long been known to slow physical performance. Now there's evidence that too little water can hurt cognitive performance, too, making complex thinking tasks harder.

More than 7.8 million high school students participate in sanctioned sports each year.

More than half the young people in a recent study were at least mildly dehydrated — maybe enough to affect energy and concentration. Roughly 25 percent said they never drink water.