Sports drinks may be of benefit in very hot and humid conditions where perspiration rates are high, leading to large losses of fluid and electrolytes, particularly sodium. Sports drinks are formulated to maximise fluid absorption and provide a source of carbohydrate and electrolytes (that may be lost in sweat).

Urine colour is also an excellent indicator of hydration levels. Urine that is clear or very pale yellow indicates a good level of hydration. (Be aware that this test is not valid if you take vitamin/mineral supplements because these often cause urine to be darker in colour)