Originally Posted by Carbonfiberboy

Since you (and the rest of us) are so interested in this and you have the subjects and equipment, perhaps you could do an experiment. What if you broke your cyclists into 2 groups, one fed with carbs 2 hours before the test, one not fed or fed with only fat. Then have them execute a ~45' climb at say 90% FTP or so and at the finish measure lactate levels. Is there an obvious statistical difference? Were both groups able to hold their power? IOW, does being fed alter the mix of energy pathways as I think you are alleging? I ask this question because yesterday I did the final pass climb of a 65 mile/5000' ride at a steady 96% LTHR, well fed with carbs, and experienced no burn, though the last 10 minutes required a little teeth-gritting as I got tired. Took me 42', which might be a PR.