Water is the most important substance you consume — and the most neglected. A dehydration of just 2% of bodyweight produces measurable performance decrements. At 3–4% dehydration, strength and endurance capacity drops 20–30%. Yet most training sessions begin in an under-hydrated state.
Hydration and Performance
- ❤️ Increased heart rate at a given workload (cardiac drift)
- 🌡️ Impaired thermoregulation and higher core temperature
- 🧠 Reduced cognitive function, reaction time and coordination
- 💪 Decreased muscle strength and endurance
- 🔁 Poorer nutrient transport and post-training recovery
Electrolytes Matter
Sweat contains electrolytes, not just water. Sodium is the most critical — it regulates fluid balance at the cellular level. Drinking large volumes of plain water without electrolytes can actually lower blood sodium to dangerous levels (hyponatraemia) — a real risk in ultra-endurance events.
How Much to Drink
| Situation | Recommendation |
|---|---|
| Daily baseline (rest) | 30–35 ml per kg bodyweight |
| Active training day | 40–50 ml per kg bodyweight |
| During training (<60 min) | 400–800 ml/h, plain water sufficient |
| During training (>90 min) | 400–800 ml/h with electrolytes |
Summary
Hydration is fundamental to performance, recovery and health. Start training well hydrated, drink 400–800 ml per hour during sessions, and include electrolytes for efforts exceeding 60–90 minutes. Light yellow urine is your confirmation you’re getting it right.
