[kfisherx]

Are there any generally accepted ideas, articles, studies or references on fat burning and cardio or is this just a subject of too much controversy for people to generally agree? I am looking around this site and the web for my and not being succesful on finding articles that do no conflict somewhat. I fear this is sort of like the whole squat debate and that I will have to go through another long series of questions to really get what I think is right amongst all the opinions.

Specifically I am looking for answer to the following?

At what point in a cardio routine does a person go from fat burning to LBM burning?

I am reasonably familar with the heart rate zone concepts and how they work as far as burning fat versus carbs but I don't get them to this detail.

I am asking this question because at the gym where I train the head trainer talks like he knows this definitively to his clients telling them that if they work out at Borg PRE scale of somewhat hard or hard (I think this translates to HR 140-160) that they are burning LBM. I don't agree with him in my gut but I cannot really point to any definitive source and am finding that many of the sources conflict with one another.