The triathlon training blog of Phil Barnes

Metabolic data from Physiology Test

I received the full metabolic data analysis from my physiology testing. Here's a snap shot of the spreadsheet:

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Here are the spreadhseet calculations to compute the calories from fat, and calories from carbs:

Calories from fat (kcal)

Calories from carbs (kcal)

Column J, Respiratory Exchange Ratio = CO2 expired / O2 consumed

If you plot the % Calories from fat and the % Calories from carbs against Heart Rate, you can clearly see a cross-over point around 120 bpm where the majority of my energy expenditure is coming from carbs. As I understand it, proper heart rate training will push this threshold up, so that at a higher heart rate, you are burning more fat. This makes your body more efficient on long distance or endurance events, as your body has much larger stockpiles of fat, than carbs. I think I heard somewhere you can only last for 1.5 to 2 hours max on carbs alone, whereas you could theoretically go for 2 days by burning fat.

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