Besides going to a performance lab, how would you determine one of your athletes has a world class fat oxidation rate?
You can get a very rough approximation through lactate testing. Lactate is only produced through glycolysis so any fat burn that you have is lowering the glycolysis need. There’s a lot of confounding factors like lactate clearance rates. But very generally if you see an athlete with a high threshold power output and a low blood lactate value you can infer that a “world class” amount of output is generated through fat oxidation.