Exercise Physiology | Respiratory Quotient (RQ): What is it?

The video explains the concept of the respiratory quotient (RQ), which is the ratio of exhaled CO2 to inhaled O2, and its role in determining the predominant fuel source during exercise. It discusses how RQ values vary between 0.7 and 1, depending on whether glucose or fatty acids are being metabolized. The video also covers how exercise intensity affects RQ, with higher intensities favoring carbohydrate metabolism and lower intensities favoring fat metabolism. The importance of steady state exercise in measuring RQ is emphasized, and examples are provided to illustrate how RQ can indicate the balance of fuel sources used during different exercise intensities.

What does an RQ value of 1 indicate about the fuel source being metabolized?

• Exclusive metabolism of fats

• Exclusive metabolism of glucose

• Equal metabolism of fats and glucose

• Metabolism of proteins

In what condition is the RQ value exactly 1 during exercise?

• At rest

• During low-intensity exercise

• At VO2 max or super maximal exercise

• During moderate-intensity exercise

What is the typical RQ value when fatty acids are the primary fuel source?

• 1.0

• 0.7

• 0.5

• 0.85

Which fatty acid is used as an example to explain the RQ value of 0.7?

• Stearic acid

• Myristic acid

• Caproic acid

• Palmitic acid

At 50% VO2 max, which fuel source contributes more to energy production?

• Fats

• Proteins

• Carbohydrates

• Water

What does an RQ value closer to 0.7 indicate about exercise intensity?

• No exercise

• Low exercise intensity

• Moderate exercise intensity

• High exercise intensity

How does the crossover effect relate to exercise intensity and fuel source?

• It shows that only fats are used at high intensity

• It indicates a switch from carbohydrate to fat metabolism as intensity increases

• It describes the shift from fat to carbohydrate metabolism with increasing intensity

• It suggests that proteins are the main fuel source at all intensities