Just a 2% decrease in body weight, as a result of sweating, can lead to a drop in performance.
Because of this it’s no surprise that hydration is one of the most important parts of exercise; replacing the fluids and electrolytes lost as sweat is vital so you can achieve peak performance and stay hydrated. Failing to stay hydrated will result in you experiencing the negative effects, like reduced performance, increased strains placed on your body, decreased work rate and an increased feeling of exertion.