A question on Calories

That’s an insanely easy pace on the trainer.

Imagine your racing for an hour was an all-out time trial – one hour at FTP. That’s 305 W. Now, if you were racing, it’s probably not that even a power output (VI > 1). You’ve still got to average 305 W to burn 1100 calories, so that means your NP was more than 305. A typical VI for a road race seems to be around 1.2, maybe, so that makes for an NP of 365 W, held for one hour.

Your easy hour on the trainer is 600 calories, which is 165 W. If your race was an all-out effort, that means your easy hour was at 45% of FTP. That’s really easy!

If you wanted to match the 1100 calories of racing, you could hold a constant 245 W for one hour 15 minutes. That would be less than 70% FTP. Which do you think is easier and more repeatable, racing full-bore for an hour, or 70% FTP for 1.25 hours?

To maximize calorie burn:

  • More time is more effective than harder effort. The relative difficulty of producing X watts increases quickly (faster than linear), but the actual energy consumed just increases proportionally.
  • Even effort is more effective than varied effort. Varying your work level makes the NP (the “relative difficulty”) higher than the average power (the amount of energy consumed).
  • If time is limited, use the highest effort level you can sustain and repeatably recover from.
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