HOW TO DO IT Look for packaged hyperhydration products including Osmo Preload Hydration (for men and women) and Skratch Labs Hyper Hydration. Or try Nuun Electrolytes Hydration Tablets (3 in 500ml water the night before; 6 in 500ml water the morning of). Be warned: hyperhydration is salty; the taste is strong.
Hyponatremia
Sometimes called ‘water intoxication’, this is a serious condition where blood sodium levels are dangerously low, which can cause nausea, cramping, confusion, slurred speech, and in extreme cases, seizures, coma, even death. It’s rare, but happens most often in long endurance events when competitors drink more fluid than they sweat or pee out. Aim for about 500 to 750ml fluid (about a large bike bottle’s worth) an hour, but no more than 800ml, says Sims.
Electrolytes
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