Why Some Sweat More

Hilary Achauer investigates the science of sweat and busts the myth that fitness alone determines liquid loss.

At the end of your next CrossFit class, look around.

You’ll see some people soaked in sweat, a telltale puddle under the bar. Others who just completed the same workout in the same environment are almost completely dry.

Everyone sweats, but why do some people sweat so much more than others? Do heavy sweaters need to hydrate more than those who merely glisten?

We tend to associate perspiration with fitness, and it’s not entirely wrong to do so. Exert yourself for an extended period of time, and it’s likely you’ll sweat. From the 1980s through 2014, a number of studies showed fit people sweat sooner and more than their sedentary counterparts.

Recently, scientists have taken a closer look at these studies and discovered although exercise and sweat are correlated, improv- ing your fitness will not make you sweat sooner, more efficiently or in greater quantities. And for heavy, salty sweaters, flooding the body with liquid, including sports drinks, is not the best way to replace lost electrolytes.