-
The ratio moves towards higher CHO use at higher intensity.
I don't get what you're trying to work out?
"It is well-established that whole body fat oxidation increases with exercise intensity up to ~55-65% of VO2max, but decreases at higher exercise intensity [1, 22]. Why fat oxidation decreases at high exercise intensities is not completely understood, but evidence suggests a decrease in FFA availability due to a decrease in blood flow to adipose tissue, a limited capacity per unit time to generate ATP from oxidation of plasma FFA, or a decrease in the activity of CPT1 [1]. The exercise intensity at which maximal fat oxidation rates occur varies according to training status, sex, and mode of exercise. Maximal fat oxidation rates (~05.-0.6 vs. ~0.4-0.5 mg · kg−1 · min) and the intensities at which this occurs (59% - 64% vs. 47-52% of maximal oxygen consumption (VO2max)) are higher in highly trained vs. moderately trained individuals. Maximal fat oxidation rates appear to be higher in women compared to men; fat oxidation rates are higher at a given exercise intensity in females, and occurs at a higher exercise intensity. Although the mechanism is not clear, the ability of females to utilize more fat during exercise may be due to differences in levels of circulating hormones and catecholamines, a more oxidative muscle fiber type distribution, an increased sensitivity to catechomlamine stimulated lipolysis, or increased activity of hormone-sensitive lipase [1]. Maximal fat oxidation rates also appear to be higher during walking and running compared to cycling, which may reflect recruitment of a smaller muscle mess and a lower catecholamine response during cycling [1]."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2885974/
Absolute (A and B) and relative (C and D) 24-h carbohydrate (Carb) and fat oxidation in men (M; gray bars) and women (F; open bars). Values are means ± SE; nos. within bars are means. Con, no-exercise day; LI, low-intensity aerobic exercise day; HI, high-intensity aerobic exercise day; FFM, fat-free mass. (P > 0.05).
hippy-
I don't get what you're trying to work out?
The following (thanks for the links) answers my queries:-
"It is well-established that whole body fat oxidation increases with exercise intensity up to ~55-65% of VO2max, but decreases at higher exercise intensity [1, 22].
So if you go above that magic 55-65% of VO2max range then your body starts to burn less and less fat. You can see why the 'fat burning zone' became popular because they took this single fact in isolation and didn't consider the wider picture, especially...
Why fat oxidation decreases at high exercise intensities is not completely understood...
Along with why stuff like HIT alone seems to work for fat loss (as shown by the Michael Mosely documentaries) despite it being contrary to the points above.
Greenbank
I'd need to see the data behind that graph as just the relative comparison doesn't tell anyone if the number of calories obtained from burning fat is staying the same, increasing or decreasing as intensity increases.
Going back to my made up figures:-
Those numbers give a decrease in the relative contribution from fat, but an actual increase in absolute contribution from fat.