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) used during metabolism. It provides insight into which fuel (carbohydrates or fats) is being metabolized.

2. How Does the Calculator Work?

The calculator uses the RER formula:

Where:

• \( VCO_2 \) — Carbon dioxide output (mL/min)
• \( VO_2 \) — Oxygen uptake (mL/min)

Explanation: The ratio compares the volume of CO₂ exhaled to the volume of O₂ inhaled during respiration.

3. Importance of RER Calculation

Details: RER is important for understanding metabolic fuel utilization, assessing exercise intensity, and determining resting metabolic rate in indirect calorimetry.

4. Using the Calculator

Tips: Enter VCO₂ and VO₂ values in mL/min. Both values must be positive numbers. Typical RER values range from 0.7 (pure fat metabolism) to 1.0 (pure carbohydrate metabolism).

5. Frequently Asked Questions (FAQ)

Q1: What does an RER of 0.7 mean?
A: An RER of 0.7 indicates pure fat metabolism, typical during fasting or at rest.

Q2: What does an RER of 1.0 mean?
A: An RER of 1.0 indicates pure carbohydrate metabolism, common during high-intensity exercise.

Q3: Can RER exceed 1.0?
A: Yes, during hyperventilation or high-intensity anaerobic exercise, RER can temporarily exceed 1.0.

Q4: How is RER measured in practice?
A: RER is typically measured using metabolic carts that analyze expired gases during breath-by-breath analysis.

Q5: What factors affect RER?
A: Diet, exercise intensity, metabolic state, and respiratory conditions can all affect RER values.