Hello, I'm Dr. Smith, a respiratory physiologist with over 20 years of experience in the field. I'm here to help you understand how to calculate RER.

The Respiratory Exchange Ratio (RER) is a measure of the ratio of carbon dioxide (CO2) produced to oxygen (O2) consumed during respiration. It provides insights into the body's fuel utilization, particularly the relative contribution of carbohydrates and fats.

To calculate RER, you need to measure the volume of CO2 produced and the volume of O2 consumed during a specific period. The formula for RER is:

RER = VCO2 / VO2

Where:

* VCO2 is the volume of carbon dioxide produced (in liters per minute, L/min).
* VO2 is the volume of oxygen consumed (in liters per minute, L/min).

Steps to Calculate RER:


1. Measure VCO2:
- This can be done using a metabolic cart, a device that measures the concentration of CO2 in the expired air and the volume of air expired.
- The expired air volume is multiplied by the CO2 concentration to obtain the volume of CO2 produced.


2. Measure VO2:
- The metabolic cart also measures the concentration of oxygen in the inspired and expired air.
- The difference between these concentrations, multiplied by the volume of air expired, gives the volume of oxygen consumed.


3. Calculate RER:
- Divide the VCO2 by the VO2 to obtain the RER.

Interpreting RER Values:

- RER = 0.7: This indicates that fat is the primary fuel source.
- RER = 1.0: This indicates that carbohydrates are the primary fuel source.
- RER > 1.0: This usually indicates an overproduction of CO2, which could be due to hyperventilation, buffering of lactic acid, or other metabolic disturbances.

Importance of RER:

- Fuel Utilization: RER helps determine the relative contribution of carbohydrates and fats to energy production.
- Metabolic Assessment: RER can be used to assess the efficiency of metabolism and identify potential metabolic disturbances.
- Exercise Physiology: RER is a valuable tool in exercise physiology to monitor and adjust exercise intensity and duration.

Limitations of RER:

- Accuracy: The accuracy of RER measurements depends on the quality of the equipment and the accuracy of the measurements.
- Individual Variability: RER values can vary significantly between individuals due to factors such as age, sex, and fitness level.
- Metabolic State: RER can be influenced by the metabolic state of the individual, such as fasting, feeding, or exercise.

Conclusion:

RER is a valuable tool for understanding fuel utilization and metabolic processes. By accurately measuring the volumes of CO2 produced and O2 consumed, you can calculate RER and gain insights into the body's fuel preferences and overall metabolic health.

read more >>

The respiratory exchange ratio (RER) is the ratio between the amount of carbon dioxide (CO2) produced in metabolism and oxygen (O2) used. ... Measuring this ratio can be used for estimating the respiratory quotient (RQ), an indicator of which fuel (carbohydrate or fat) is being metabolized to supply the body with energy.read more >>