Claim
mechanistic
Standard methods for measuring whether the body is burning carbs or fat during exercise overstate carb use because they measure carbon dioxide from the whole body, not just from muscles, making it seem like carbs are used more than they actually are.
Claim Context
Scientific statement
Respiratory gas analysis overestimates carbohydrate oxidation during high-intensity exercise because exhaled CO2 reflects body CO2 stores rather than direct muscle metabolism, leading to inaccurate conclusions about fuel use.
Original statement
“The method of measurement, respiratory gas analysis, also overestimates the true extent of CHO oxidation as exhaled CO2 arises from body CO2 stores, not from muscle metabolism, artificially inflating the apparent contribution of CHO oxidation at higher exercise intensities.”