Hydration & Electrolyte Calculator
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The Science of Sweat
One size does not fit all. The "8 glasses of water a day" rule is outdated myth, especially for endurance athletes. The Invigorate Precision Hydration Calculator uses metabolic science to estimate your specific fluid and electrolyte losses based on three critical variables: Intensity, Duration, and Environmental Conditions.
Dehydration of just 2% of your body weight can reduce aerobic performance by up to 20%. Conversely, over-drinking plain water can lead to Hyponatremia (low blood sodium). This tool finds your sweet spot.
Why Sodium Matters More Than Water
When you sweat, you don't just lose water; you lose critical electrolytes, primarily Sodium. Sodium is the mechanism that allows your body to hold onto fluid. Without it, the water you drink passes straight through you, doing nothing to rehydrate your cells or blood plasma volume.
- Prevent Cramping: Neuromuscular fatigue combined with electrolyte imbalance is a leading cause of muscle cramps.
- Maintain Blood Volume: Proper sodium intake keeps your blood volume high, reducing the strain on your heart (Cardiac Drift).
- Mental Clarity: Electrolytes are essential for nerve transmission. Staying hydrated keeps your focus sharp at mile 20.
Frequently Asked Questions
When should I drink electrolytes?
For workouts under 60 minutes, water is typically sufficient. However, for sessions longer than 60-90 minutes, or high-intensity intervals in heat, you should begin sipping an electrolyte mix 30 minutes prior to starting and continue every 15-20 minutes during activity.
How do I calculate my Sweat Rate?
This calculator provides a scientific estimate. for 100% precision, try a simple home test: Weigh yourself naked before a 1-hour run (no drinking during). Weigh yourself after. The weight lost (in lbs/kg) is roughly your hourly fluid loss.
How does this fit into my training plan?
Hydration strategy is just one pillar of performance. To see how these hydration numbers fit into a full season of training, generate a free custom schedule with our Marathon Training Plan Generator.
Berry
Citrus
Raw
300g (90 servings) = 25p per serving
Why you need electrolytes
Electrolytes like sodium, potassium, calcium, and magnesium are the electrical sparks that keep your body running. They regulate fluid balance, muscle contractions, and brain function. Without them, water alone can't fully hydrate you, leading to fatigue and cramping. Dive deeper into the science below:
