Formula for intensity comparrison

Hi, Just wondered if anyone had any formulae (speadsheet of maths), to calculate either the intensity of a rep of recovery. i.e. so I can determine if for instance if 3 minutes at 250W is the same is 2 minutes at 300W.
Just a thought!


Any measure of intensity or training load will depend on the output relative to your FTP and generally the duration of the entire work out. Here are the basic equations as I understand it (

FTP = Functional Threshold Power (the maximum power you could hold for 1 hour at a constant output)

Normalized Power (NP) is a complicated formula meant to give an equivalent constant power output from a varying output effort.

  1. Compute 30s rolling average power
  2. Raise the rolling average power computed in step 1 to the 4th power
  3. Calculate the average of the values from step 2
  4. NP is the forth root of the average from step 3

Intensity Factor (IF) = NP / FTP
Note: this does not factor in the duration of the effort

Training Stress Score (TSS) = (t * NP * IF) / (FTP / 3600) * 100
where t is the time of the entire effort

These were meant to apply to a total workout not just a short segment and I don’t know how applicable they are. Certainly TSS would better than IF if you’re trying to compare two efforts with different time and IF doesn’t take time into consideration.

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