1. What is Respiratory Exchange Ratio?

The Respiratory Exchange Ratio (RER) is the ratio between the amount of carbon dioxide (CO₂) produced and oxygen (O₂) consumed during metabolism. It provides insight into which fuels (carbohydrates vs. fats) are being metabolized.

2. How Does the Calculator Work?

The calculator uses the RER equation:

Where:

• \( VCO_2 \) — Volume of carbon dioxide produced (mL/min)
• \( VO_2 \) — Volume of oxygen consumed (mL/min)

Explanation: The ratio indicates the relative contribution of carbohydrate and fat to energy production.

3. Importance of RER Calculation

Details: RER is important in exercise physiology, nutritional assessment, and metabolic studies. It helps determine:

• Primary fuel source being utilized
• Metabolic efficiency
• Exercise intensity thresholds

4. Using the Calculator

Tips: Enter both VCO₂ and VO₂ in mL/min. Values should be measured under steady-state conditions for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What do different RER values indicate?
A: RER of 0.7 indicates pure fat metabolism, 0.85 mixed fuel, and 1.0 pure carbohydrate metabolism. Values >1.0 occur during hyperventilation or high-intensity exercise.

Q2: How is RER measured clinically?
A: Typically measured using indirect calorimetry during rest or exercise.

Q3: Does RER change with diet?
A: Yes, high-carb diets increase RER while high-fat diets decrease it.

Q4: What factors affect RER?
A: Exercise intensity, diet, metabolic state, and respiratory conditions can all affect RER.

Q5: Is RER the same as RQ?
A: RER (respiratory exchange ratio) reflects gas exchange, while RQ (respiratory quotient) reflects cellular metabolism. They are equal under steady-state conditions.