VO2 Max intervals - questions on power analysis

Hi guys,

Completed my 4x4min VO2 max intervals today (avg 303w) compared to my 3min set 2 weeks prior (avg 307w). Very happy.

I have two questions.

  1. When can average power be greater than normalized power?

  2. I always start my intervals with a 15sec ‘jump’ at the start and for the remainder of the interval watch my avg power drop as I hold my true power for that interval length. I never have a cliff edge drop off in power but for example today my first 20sec- 30sec will average 330w but for the 4min set I’ll avg 303w holding say 295w for the last 3:30. IS THIS NORMAL?


Hey Sam,

Good questions.

For very short intervals, normalized power can be lower than average power. This is because that when calculating normalized power, each data point in the selected range is calculated using the entirety of the 30 seconds prior to itself, which is the basis of NP. The accumulation of stress in your muscle at any point in time is affected by what has happened in the prior 30 seconds of any data point in question.

As for starting your Vo2 max you don’t want to start with a sprint like that. Just get up to your pace and hold it. In your 4 minute intervals you would want to keep it as close to 300 watt range to start and not go over.


@sam - post a picture of your power and HR data from TrainingPeaks so everyone can see and we can answer too!


NP and Avg Power VO2 4min InteNormalised and Avg Power|640x480 rvals

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Normalised and Avg Power

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Ok I think I understand.

Thanks for clarification on commencing the Vo2 stets. They are not Vo2 bursts!

See above for data.

These look great @sam and the only thing I’d nit-pick is to x-nay what you describe as the 15 sec burst at the beginning.

While variable power is fine and good, ideally if you can make the top of your interval power on the graph a flat horizontal line - then you’re doing the best. The graph doesn’t have to be flat but take the 15 sec burst from the beginning and apply that energy to the last 15 seconds and without fading and you’ll finish strong