I claculated my target heart rates based on the Karvonen formula. Resting 45bpm, max 202 age 47 (not that that figures in to the calc). All well and good. However, I when I look at the five zones I am seeig a really big spread in what is considered Zone 5, 4, etc..

This is one I found on a search here:

Zone 1: < 65% max HR
Zone 2: 66-72%
Zone 3: 73-80%
Zone 4: 85-90%
Zone 5: > 90%

Ascent defaults to:

Zone 1: < 69% max HR
Zone 2: 69-77%
Zone 3: 77-85%
Zone 4: 85-93%
Zone 5: > 93%

Another one used by Sark is:

Zone 1: < 52% max HR
Zone 2: 52-64%
Zone 3: 64-76%
Zone 4: 76-88%
Zone 5: > 88%

So my question is which one makes the most sense? I know I just need to be consistent in which is getting applied but I wanted to see what the collected wisdom is.