Thank you, appreciate the reply! You did such a great job explaining the study design that I’m seriously thinking of doing a local gas exchange and lactate test.
Have you looked at the accuracy of INSCYD fat/carb oxidation estimates? Any comments on the INSCYD model with respect to these oxidation estimates?
With the high carb intake rates during exercise are other meals lower in carbs to fit normal daily carbohydrate recommendations?
yes for endurance, but no for recovery rides, since I don’t do them. I rather take the day off the bike.
I would only recommend less for endurance if someone had the day off the following day. 100g is only 400 cals, nothing!
heehee, yes sir, taller than most on the bike. lucky I stopped at 6’5" so most frames will fit me.
Dear Trek, why do you still not make a seat post that goes high enough? Been wanting to try one of your roadies for a while now!
Hope U are well Alex! Been a minute!
Brendan
A lot of people don’t have 120g of carbs per season 
Makes sense. My mid-week endurance rides are in the 180-200W range for 2 hours. Or roughly in the 1200-1500kJ range. And I’ve been fueling at 60+g/hr or about 500-800 calories. Hitting 100g/hr isn’t a stretch, and roughly 50% of calories burned (assuming kJ = kcal) at the top-end of my range.
While the INSCYD using lactate can predict VO2max and MLSS https://www.researchgate.net/publication/361692922_Utility_of_INSCYD_athletic_performance_software_to_determine_Maximal_Lactate_Steady_State_and_Maximal_Oxygen_Uptake_in_cyclists I am not convinced that it is worth doing and would rather suggest doing a proper LT profiling.
Though I personally haven’t done any test myself for a looooong time and have been using TrainerRoad’s AI to determine my threshold. And then I guess the LT1.
In terms of substrate oxidation rates - I think that is bullshit because there are so many factors influencing it that it’s pointless to even try and predict it. And measuring it isn’t useful either if you ask me. Unless you are doing a study 
This is a very good question! I like to say that starting glycogen is more important than the on-the bike fuelling. The latter can perhaps rescue insufficient fuelling off the bike to a certain extent, but definitely cannot be a substitute. It is thus always “fuel for the work required”. Intense workouts - plenty of carbs before and during. Easy workouts - not so many carbs before and not so many during. So that at the end of the week, you end up being in a caloric balance.
Thank you for saving me $250 
I’ll just keep experimenting at 60-120g/hr.
Same although a different path. I came up with a methodology for threshold testing and estimation back in 2017. And then in early 2020 found out my Garmin 530 machine learning also does a great job at estimating threshold. Haven’t done a lot of tests except 2 years of TR ramp testing (2018 and 2019).
You are the best!
My coach helped me with LT1 estimation and I feel really good about our estimates. When I ask him about testing he agrees with you although with more diplomatic words until I use my sales skills and get him to be brutally honest and drop the diplomacy. I say drop the and get real!
Cheers and thank you again!!!
that’s right. so no need to go into a deficit that much. 100g an hour and you still have to make up 800 cal; plenty of room for carbs. stay topped off and crush the next workout.
Endurance carb daily recommendations should be higher than normal folks.
But yes, count your carb intake during training towards your daily total if you’re taking things.
Oh, you and I are going to have so much fun when we finally talk.
Folks, when this man speaks (or writes), LISTEN UP.
Sorry, hit a nerve. Testing is overdone. Thank you for your sensibility.
I would totally love to see more studies on the potential negative effects of high fructose consumption as well. But also remember that ATP acts as an inhibitor to phosophofructokinase, exercise may actually increase the PFK inhibition, lowering potential downsides. I always remind myself that it’s too easy to jump to conclusions based on our knowledge of some mechanism, but the system as a whole might be doing something else entirely.
@Dr_Alex_Harrison @timpodlogar are there down sides to using high carbs as suggested in training and also eating very high carb throughout the rest of the day and week?
I’ve experimented with a low fat and lowish protein and very high carb diet for a few months.
But if he rides don’t even try to follow because he’s a really strong bike rider 
a few weeks ago when I was in Otzal he was at the top of every segment “today” and there is a lot of pros training there
I really liked this vid. Liked the progression from “here is what the authors can say in a peer reviewed study” to “here is what a reasonable person could conclude - with caveats.”
Yes. I touch on that here: How Much Carbohydrate To Go Faster? - YouTube (look for the part about when Michelle’s fasting glucose started drifting up when we were slashing her fat and protein consumption as an experiment).
Maybe he and I can chat about this more on our recording call.
Thank you for doing this. It’s important. We all should take note.
Thanks - it’s next on the list.
My own experience (without glucose measuring) was that I felt I was eating more than ever and losing weight. Training fell off a cliff after 4 weeks of higher volume.
Sounds like you might not have been meeting kcal needs. Carbs can be very high-volume and filling, so can feel like you’re force-feeding, but you end up falling short of kcal balance. That’ll tank performance after a few weeks, for sure, especially if training was somewhat ramped up at the same time.
I’d bet that for you, the primary reason performance went down was not necessarily because of the high percentage of carbohydrate in the diet, but simply because it’s hard to eat lots of carbs without fat and protein to make it taste better, and so you ended up in a kcal deficit.