If you stop to consider that we are only able to bring in about 60g-90g of carbs per hour, that implies that our carb dependent workload is limited to somewhere around 67w to 100w per hour. for long endurance events As such, it is critical to be able to metabolize a considerable amount of fat in order to push the pedals hard. If I am constantly cramming in carbs in order to manage the TR plans with a heavy focus on sweetspot and threshold work, aren’t I shooting myself in the foot if long endurance events are my focus? I.e. the sustained power build and century plans seem very ill suited for my types of events.
This was more or less validated by a very recent INSCYD Test with lactate. My TR FTP is ~293w, my XERT and WKO4 FTP are ~285w, my INSCYD AT is ~230w (213w to 246w). The INSCYD Test with Lactate shows that at a paltry 191w of work, I am burning 62% carbs. At 230w to 246w, INSCYD shows me burning pure glycogen…I.e. I was producing a ton of lactate at these lower levels, which I think is largely a function of relying so much on carbs to be able to even attempt the more strenuous prescriptions of sweetspot and threshold work in the mid-volume sustained power build and century specialty plans.
If I assume I have 400g of carbs available on board between the muscle stores and liver that can be employed to work for 10 hours, I would have ~44w/hr to work with (400g x 4kcal/g = 1,600 kcal / 3.6/w = 44w/hr. If I can input another 83w/hr (75g/hr) that means anything over 127w must come from fat oxidation. Therefore, I am effectively capped at ~191w to ~200w of work/hour for long events.
I think there is something too being able to work at a higher percentage of a lower FTP vs a lower percentage of a higher FTP…as such, I question the efficacy of the sustained power build and century specialty plans as the prescription for long endurance athletes…? To be clear, I am not advocating a keto diet, but rather a plan that could focus more on fat oxidation as a fuel source. Sweet spot and threshold work does not really allow for this…