I was fortunate enough to have some lab testing done recently and I’m trying to work out what it all means, specifically the use of fat and carbs as fuel. I’ve attached the outputs from the tests for anyone interested enough to analyse. The test order was 1) 10 min warm up @100W then Sub max test, 2) 10 min @ 100W then Vo2 max, and 3) 2h rest and then Time to exhaustionVo2.pdf (308.6 KB)
TTE.pdf (299.2 KB)
Submax.pdf (318.6 KB)
Regarding the fat/carb source utilization, I have a few questions:
- looking at test 1 (sub max), I burn primarily carbs, even at low intensities. Correct?
- However, test 2 (VO2 Max) relies mainly on fats…is this because the carbs have been exhausted?
- TTE relies on fat at low W, but then once load is applied at 470W, carb use dominates (this is what I expected to see across all test fat>carb).
I train primarily in the mornings around 6am in a fasted state (i.e., nothing from 7pm previous evening) and was surprised by the sub max test. Does this really mean that I primarily rely on carbs as a fuel source until they’re exhausted, after which I switch to fats? If so, how was I able to reach VO2 max in the 2nd test, despite pulling the fuel from fat (which is far slower chemical reaction).
I find it very hard to lose weight despite a lot of training and any insights into my results would be appreciated!! I didn’t pay for the tests (part of a trial) and RER was provided without explanation or analysis.