up a sweat, it’s crucial to stay hydrated. “When you are dehydrated, you’ll feel an increase in physical strain, core temperature, heart rate, and rates of perceived exertion. And the greater the fluid deficit, the greater the strain”, says Molly Morgan, a nutritionist based in Vestal, New York, USA. If your fluid loss hits 2% or higher, it can compromise your physical and mental performance, she adds.
