What is the Difference Between RQ and RER?
🆚 Go to Comparative Table 🆚The Respiratory Quotient (RQ) and Respiratory Exchange Ratio (RER) are both measures that indicate the type of fuel (carbohydrates or fats) being metabolized by the body to supply energy. However, there are key differences between the two:
- Measurement location: RQ is a direct measurement taken from the blood, while RER is an indirect measurement taken at the nose or mouth.
- Invasiveness: RQ measurement requires the insertion of a catheter into a vein or artery to take a blood sample, making it an invasive and less convenient method compared to RER.
- Accuracy: RER can be used to estimate RQ during rest and mild to moderate aerobic exercise, but it is less accurate during intense anaerobic exercise.
- Range: RQ value ranges from 0.7 to 1.0 and cannot exceed 1.0, unlike RER, since RQ reflects tissue substrate use.
- Conditions: RQ should be measured under resting or steady-state exercise conditions, while RER can be observed and calculated at the nose or mouth.
In summary, RQ is a more direct and invasive measurement taken from the blood, while RER is a less invasive and more convenient measurement taken at the nose or mouth. RER can be used to estimate RQ during certain conditions, but it is not as accurate as RQ in reflecting tissue substrate use.
Comparative Table: RQ vs RER
The respiratory quotient (RQ) and the respiratory exchange ratio (RER) are both measurements related to the oxidation of fuels in the body. Although they are considered the same measurement, under certain circumstances, their values can differ due to the components of the measure being obtained differently. Here is a table summarizing the differences between RQ and RER:
| Feature | Respiratory Quotient (RQ) | Respiratory Exchange Ratio (RER) |
|---|---|---|
| Definition | Used to estimate metabolic stoichiometry. | Indicator of the type of fuel (fat vs. CHO) being metabolized. |
| Range | 0.7 to 1.0. | < 0.7 to > 1.2. |
| Under Steady State | RQ and RER are equal. | RQ and RER may vary. |
| Conditions for Variation | - Metabolic acidosis. |
- Nonsteady state exercise.
- Hyperventilation.
- Excess postexercise VO2.
- Prolonged exercise (if CHO nutrition was poor and muscle and liver glycogen are low). | - During fat metabolism, there is less CO2 produced for O2 consumed.
- During carbohydrate metabolism, there is an equal amount of CO2 produced for O2 consumed (RER = 1.0). |
It is essential to note that the RQ and RER values may vary under specific conditions, and their accuracy can be affected by factors such as air leaks, extreme pain or agitation during the measurement, and recent procedures that affect gas exchange.