Hydration basics
Under an hour, water when thirsty is usually enough. Long hot sessions need a tested fluid and sodium plan.
BALANS in practice
Weigh before and after once — then you know your sweat rate better than any formula.
Training
Hydration and electrolytes
Hydration and electrolytes for aerobic training: how much to drink, when to use isotonics, and hyponatremia risks.