what do you think of a new field in the app (maybe swappable with the kJ field) that gives an estimation of the g carbohydrate you used in the workout so far? Or maybe a suggestion of how much you should take in. As the conversation shifts more and more to g carbohydrate to take in that would make sense - wouldn’t it?
Curious to what others think of that idea.
It would also vary with 1) cycling efficiency (the more efficient you are, the less fuel required), 2) habitual diet (we burn what we eat), 3) food intake in the last 6-8 h, 4) food intake during exercise, 5) sex (smaller effect), 6) menstrual cycle phase (smaller effect), 7) age (possibly), 8) other factors (e.g., genetics).
Of the above, numbers 2 and 3 would likely be the biggest source of error.
IOW, unless you really know what you’re doing - perhaps even if you know what you’re doing - it would be a WAG. Now could you estimate things closely enough for the calculations to provide “actionable intelligence”? Time will tell.
I’m not asking about carb/fat split just how much carbs to take in during a workout, I’ve never heard of anyone trying to take in a specific amount of fat during a race or workout. FTP/Intensity of the workout and weight would be needed to be considered for suggested carb intake I would expect. I would think at 58kg, I’m probably not going to need as much as someone who is 80kg at the same IF. At the same time it sounds like maybe nobody can take in enough carbs per hour to keep up with the burn rate in a race or hard workout.
At best, that’s only going to be loosely associated with how much carbohydrate you actually oxidize during exercise, due to 1) muscle glycogen being the primary source of carbohydrate and energy (and also not being influenced by carbohydrate supplementation during exercise), 2) variable liver glycogen stores, and 3) unknown factors (e.g., the rate of carbohydrate absorption during exercise).
TL,DR: The best way to determine how much carbohydrate (and water) to ingest during exercise is to experiment on yourself. In particular, no app/algorithm/program is (can be) accurate enough to be worth the investment (in terms of money or just time).
If you want to know how much to eat during a ride I suggest you check out EatMyRide. It has a data field for your Garmin Edge where you can track your burn and consumption in real time, I.e. it will show him much you have depleted so far based on the watts you are producing and you add what you eat as you ride. The app takes into account that it takes some time to digest different types of carbs, so even if you eat 200 g now it will only be available for your muscles gradually.
There is also a functionality for planning a ride.
I am sure all these things will have an impact. However, I think Xert will make some assumptions to calculate how much carbs and fat you will burn during the ride and TrainerRoad would have to do something similar.
TR seems to assume an approx 25% efficiency (direct kJ;s to Kcals). When I did a met cart test a while back it gave an indication that I was only 18-19% efficient at the intensities I generally ride at. That makea a large difference in Kcals burnt and hence I assume carbs
Indeed, almost everyone’s efficiency will be lower than ~25%. Not only that, but gross efficiency varies with exercise intensity (as you implied). Just one more reason such estimates are a WAG at best. (This is also why they weren’t implemented in WKO4 - I don’t like lying to people by claiming to be able to calculate something accurately that can’t be. Same reason my ideas dFRC were never implemented.)