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Sweat Test Calculator

Determine your individual sweat rate for running and cycling. Create sport-specific hydration strategies based on your unique physiology and the different demands of each discipline.

How to Perform a Sweat Test

1

Pre-Exercise

Empty bladder, then weigh yourself nude or in minimal dry clothing. Note the exact weight.

2

During Exercise

Exercise at race intensity for 30-60 minutes. Track all fluids consumed. Avoid urinating if possible.

3

Post-Exercise

Towel off sweat, remove wet clothes, and weigh yourself again in the same state as pre-exercise.

4

Calculate

Enter your data below to determine your sweat rate and receive personalized recommendations.

Test Data - Running

Test Conditions

Your Running Results

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Sweat Rate (L/hr)
This is your hourly fluid loss rate under these specific conditions. --
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Sweat Rate (oz/hr)
Your hourly fluid loss in ounces for easy reference during training.
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Estimated Sodium Loss (mg/hr)
Based on average sodium concentration in sweat. Individual testing recommended for precision.

Sport-Specific Considerations

Typical Rate Difference
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Gut Absorption Capacity
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Practical Intake Limit
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Replacement Target
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Personalized Running Recommendations

💧 Fluid Replacement

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🧂 Sodium Strategy

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⏱️ Hydration Timing

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Your Running Hydration Plan

Time Fluid Target Sodium Target Notes

⚠️ Important Considerations

This plan is based on your test conditions. Adjust for race day weather, altitude, and intensity. Remember that sweat rates typically differ between running and cycling - test both sports separately. Practice your hydration strategy during training to ensure tolerance.

The Science Behind Sport-Specific Hydration

  • Running: Typically 10-25% higher sweat rates due to less cooling from airflow and more muscle mass activation
  • Cycling: Better gut tolerance allows up to 1.5L/hr fluid intake vs 1.0-1.2L/hr when running
  • Sodium needs: Often higher in cycling due to longer duration, despite lower sweat rates
  • Temperature regulation: Core temp rises faster when running, increasing sweat response
  • Practical limits: Running mechanics limit intake to 600-800ml/hr; cycling allows 1000-1500ml/hr
  • Gastric emptying: Reduced by 20-50% during running due to mechanical stress and blood flow changes