Glucose Oxidation Rate Calculator
Understanding Glucose Oxidation Rate
The Glucose Oxidation Rate Calculator is a vital tool for exercise physiologists, nutritionists, and endurance athletes. It determines the rate at which the body burns carbohydrates (glucose) for energy during physical activity. By analyzing gas exchange data—specifically oxygen consumption (VO₂) and carbon dioxide production (VCO₂)—we can quantify substrate utilization using stoichiometry.
How It Is Calculated
This calculator utilizes the standard equations developed by Peronnet and Massicotte (1991). These equations are derived from non-protein respiratory exchange ratios, assuming negligible protein oxidation during short-duration exercise.
The Core Formulas:
- Glucose Oxidation (g/min) = (4.585 × VCO₂) – (3.226 × VO₂)
- Lipid Oxidation (g/min) = (1.695 × VO₂) – (1.701 × VCO₂)
Where VO₂ and VCO₂ are expressed in Liters per minute (L/min).
Respiratory Exchange Ratio (RER)
The calculation also determines the Respiratory Exchange Ratio (RER), which is simply VCO₂ divided by VO₂.
- RER = 0.70: Indicates 100% fat oxidation.
- RER = 0.85: Indicates a mix of approximately 50% fat and 50% carbohydrate oxidation.
- RER = 1.00: Indicates 100% carbohydrate (glucose) oxidation.
Application in Sports Performance
Knowing your glucose oxidation rate helps in tailoring fueling strategies. Athletes generally have a limit on how much exogenous carbohydrate they can absorb (approx. 60-90g/hour). If an athlete's glucose oxidation rate exceeds their intake capability during long events, they risk glycogen depletion (hitting the wall).
Note on Negative Values: If the calculator returns a negative value for either glucose or lipid oxidation, it usually indicates that the RER is outside the physiological range for pure aerobic metabolism (either below 0.7 or above 1.0), often due to hyperventilation, high-intensity anaerobic effort, or calibration errors in gas analysis equipment.