wayno wrote:you need up to 500mg of sodium for every litre of water, thats roughly a quarter of a teaspoon of salt... this can prevent hyponatremia on days where you are sweating and drinking a lot, and helps the absorption of the water.
Whilst those numbers give guidance to salt replacement, but there can be significant variations in the individual and to the condition. As such, it's hardly an issue for the first few hours as the body's capacity to adjust accommodates any shortfall or excess. After which, the risk of salt/water imbalance increases dramatically and the only sure way to correct is through blood analyses (as often needed in hospitals). Out on the road or track, it can only be educated guesses.