IF YOU think you sweat buckets, you may be wrong. The exact volume produced during long periods of exercise can now be predicted, and it is less than expected. This could lighten the load for athletes and soldiers.
For 20 years, both have relied on an equation to predict how much water they will need to drink, given the temperature and expected level of exertion. But recent studies suggested that it overestimates sweat volumes.
To improve the equation鈥檚 accuracy, Michael Sawka of the in Natick, Massachusetts, and colleagues ran 101 volunteers through a gamut of exercises in a wide range of temperatures and humidity levels, both inside and outside. Crucially, they monitored participants during 8 hours of exercise, in contrast with past measurements taken after just 2 hours.
Advertisement
Over time, people didn鈥檛 simply keep producing more sweat. Instead, volumes 鈥減lateaued鈥�, perhaps because sweat glands were maxed out. This meant the total over a long period was less than expected (Journal of Applied Physiology, ).
When Sawka鈥檚 team used these findings to create a new equation, it predicted sweat volume with 95 per cent accuracy. 鈥淭here was a great need to improve that prediction equation, for military and public health, and safety and disaster relief,鈥� Sawka says.