Sports hydration

Baseline 30–40 ml/kg body weight per day. During training — 400–800 ml/hour depending on sweat rate. Weigh before/after: 1% mass loss = dehydration.

Sodium is key: 300–800 mg/hour during intense training over 1 hour. Potassium, magnesium — from food. Solution: 0.5–0.7 g salt + 30–60 g carbs per liter.

2–3 hours before — 400–600 ml. During — 150–250 ml every 15–20 min. After — 150% of lost mass over 2–4 hours. Thirst means already −1% mass.

Thirst, dry mouth, dark urine, headache, 10–20% performance drop. Over 3% mass loss — heat risk, stop training.

Too much water without salt dilutes sodium — dangerous on marathons over 4 hours. Drink to thirst + electrolytes on long events, not liters 'just in case'.

Water — for sessions under 60–90 min. Isotonic — 90+ min or heat. Coffee counts toward the norm (mild diuretic). Alcohol slows recovery.