Hydration is a frequently overlooked performance factor for runners. A good hydration strategy can improve your times by 5–10%.
Hydration is a frequently overlooked performance factor for runners. A good hydration strategy can improve your times by 5–10%.
A body water loss of only 2% of body weight reduces performance. At 3% you feel fatigue. At 5%+, risk of heat illness.
- ❌ Dehydration 2%: -10% performance
- ❌ Dehydration 3%: -15% performance, discomfort
- ❌ Dehydration 5%+: Medical risk
📋 The personalized formula
Before (2-4h prior)
- Water: 400–600ml (pale urine = well hydrated)
- Electrolytes: optional unless very hot
- Goal: arrive well hydrated
During (efforts > 60min)
Weigh yourself before and after a session (sweat test):
- If you lose 1kg in 1h → drink 500ml per hour
- If you lose 0.5kg in 30min → drink 500ml per hour
Rule of thumb: 150–300ml every 15–20 minutes depending on intensity and heat.
After (recovery 2h post-effort)
- Volume: 150% of weight lost (ex: lost 1kg → drink 1.5L)
- Type: Water + electrolytes + carbs
- Timing: progressive, not all at once
🧂 Electrolytes: When and how
You need electrolytes if:
- ✅ Effort > 60 minutes
- ✅ Heat > 25°C
- ✅ High humidity
- ✅ Salty sweat visible
You DON'T need them if:
- ❌ Effort < 60 min (water is enough)
- ❌ Cool weather (< 20°C)
- ❌ You drink only to thirst
Sources of electrolytes?
- Sports drinks: Gatorade, Powerade (6–8% carbs, sodium 250–500mg/L)
- Homemade: 500ml water + 30g sugar + pinch of salt
- Foods: Banana (potassium), salted pretzel (sodium)
⚠️ Common mistakes
- ❌ Only drinking water (> 60min): lack of electrolytes → cramps possible
- ❌ Drinking too much at once: nausea, bloating
- ❌ Drinks that are too sugary: slows absorption (hypertonic)
- ❌ Waiting for thirst to drink: it's too late, you're already dehydrated
💡 Bivora integration
Track your hydration (amount and type) in Bivora. See direct effects on your avatar and performance. You'll quickly find your personal optimal formula.
FAQ — Hydration
When should I drink during exercise?
For efforts >60 min: 150–300ml every 15–20 min. For short efforts, water is enough.
Do I need electrolytes?
Yes if >60min, hot weather (>25°C) or heavy sweating; otherwise water suffices.