To add on this topic, there is (are) Garmin Apps available on GarminIQ, like “Fat Burner”, that records the fat (in g.) and carbs (in g.) burnt during an activity, purely based on HR.
Look at the fit file on fitfileviewer. com and look at the record messages. If it is a simple field you don’t need to write any JavaScript. You can just choose the field from the custom stream dialog.
I still get the same weird results like last week by the way, 153g CHO for a 17 minute commute ride. I guess related to the quick 500W sprint across the bridge?
I reprocessed/reanalysed the file but no difference.
Sorry I should have been more specific. It is also only cycling. I don’t think running power will work with this. When I do the HR version then running will be supported.
For me, the numbers given by this TSS equation seem too high.
I have done several metabolic cart tests and converted the data to carb and fat consumption for a given range of power.
For example 150 W → 45 g/h ; 200 W → 100g of carbs/h
I use a CIQ app called Fat/Carbs Combustion Monitor that computes along your ride the fat and carb consumption according to your power.
This morning, I did an interval workout on the trainer.
My work is 906 kJ
My CIQ app gives me 54 g of fat → 486 kcal of fat and 101 g of carbs → 404 kcal, not perfect but IMHO it’s closer to my energy expenditure vs 194 g of carbs that the TSS equation gives.
Intervals.icu is actually using the total work formula with variability index now, not the TSS one. I don’t know enough about this topic on that vs the CIQ app to comment.
It’s still overestimating for LIT / recovery / commute rides with high variability index. Riding 100w average and 127w NP gives me 300g / hour, while riding at 130w avg = NP it gives me 100g / hour, which still would be a bit high for me.
From “Muscle glycogen utilization during prolonged strenuous exercise when fed carbohydrate” (Coyle, Coggan, Hemmert, Ivy; 1986)
Study measured time to exhaustion at ~72% VO2 Max (think tempo power), when fed a sweetened placebo vs. a CHO drink.
2. From "The effects of increasing exercise intensity on muscle fuel
utilisation in humans" (Loon, Greenhaff, Constantin-Teodosiu, Saris, Wagenmakers; 200)
Same issue here with overestimation. 58min activity, 736kJ and carb estimation of 204g, which would basically mean, all the energy coming from carb. The workout was 10x20s sprints with only Z1/Z2 in between, intensity of 84%, variability 1.26 (Intervals.icu).
During long endurance ride, I also get almost all energy coming from carb, which does not look plausible.