Slide 5 of 13
Maintaining proper hydration levels is important for body temperature regulation. A loss of more than 2% of body weight as fluid usually leads to decreases in activity performance. One study even noted that performance decrements may occur with as little as 1% of body weight loss as fluid.
Gisolfi, C. (1996). Fluid balance for optimal performance. Nutrition Reviews. 54:S159-S168.