Maximum Heart Rate, Intensity Interval Training, and Heart Zones

[WavyDavey]

I've been doing HIIT training a few times a week. If you haven't heard of it, it's training alternating between low-intensity and high-intensity work. Usually high-intensity is defined as at least 85% of heart rate max, so it's a challenge. The Charge2 makes it easy to track this as the default peak zone is 85% of max.

But my doctor said the old formula of using 220 minus your age to calculate heart rate max/zones is not accurate, and I should be using the formula as outlined here: http://www.mayoclinic.org/healthy-lifestyle/fitness/in-depth/exercise-intensity/art-20046887?pg=2

Under the current fitbit calculation, someone in their late 40s could have a max heart rate of 172bpm (100%), and a peak zone at 146 (85%), and cardio starting at 120. But under the newer calculation that same person with 172 max heart rate would have a peak zone that starts much higher, 157bpm, and a Cardio zone that starts at 140bpm (70%). The fitbit cardio zone starts at 120bpm. That's quite a large difference.

This has left me wondering if my intensity training is not quite intense enough. But if the new calculation is correct, the peak zone is only 156-172bpm, which is a pretty narrow window? I know I can change the heart zones to whatever I want. I'm hoping someone with experience with HIIT type training might chime in with their experience in calculating their heart zones. Any thoughts or comments about using fitbit with HIIT is appreciated.

[AlvaroFitbit]

Hello @WavyDavey. This is quite interesting. I would like to add to always seek the opinion of a doctor and in your case a second opinion may benefit you more. Still if someone can comment about their own personal experience it will be greatly appreciated.

I'll be around!