Hi,

Concerning the NPRQ, i don't know other equations than the classical VCO2/VO2.

Then, concerning substrate oxidation, to my knowledge, the equations are the following ones.

Carbohydrates (mg/min) = 4.58R VCO2 - 3.2255 VO2

Lipid oxidation (mg/min) = -1.7012 VCO2 + 1.6946 VO2.

If you need more informations, you should have a look on articles from Brun JF et al. He worked on substrate oxidation during exercise.

Hope this helps