BlueJersey said:To train by HR you need to know what is your LTHR. Do a 3 miles time trial test (going all out). Your average HR after test is your LTHR. What is LTHR? A HR which "indicates" you are very close at going anaerobic. Is only an indication since HR has no different relation to your lactic acid in your blood. But LTHR is good enough to train on. For base miles, keep your HR at 70% of your LTHR. BTW, that's Joe Friel's HR training zones. I think other coaches use different (more) HR zones. Some even uses your max HR to start with.
Doing a 3-mile TT would not measure your "LT HR" no matter what CTS may suggest (if indeed that is what they suggest). While some coaches erroneously refer to a 1-hr TT avg HR at LT HR a 3mile TT would be even higher [HR].
If you go to a lab and get your LT measured it would firstly not be correct to give it a HR value and secondly and most importantly, LT is actually a somewhat low level, that most trained cyclists can sustain for ~ 3-hrs or so.
There are two common definitions of LT, these being the workrate (i.e., power in cycling or velocity in running) that elicits a 1mmol/L increase in lactate over exercise baseline levels. this would be ~ 2.X mmol/L
The other common definition is the work rate that elicits a lactate reading of 2.5 mmol/L.
For both of these the power would be about 10 - 15% less than you can sustain for a 1-hr TT and obviously a lot less than that which you could sustain for a 3-mile TT.
Accordingly, LT is nowhere near an anaerobic level.
In relation to the OP query, you would need to 'anchor' your HR from training to some level that you have measured. For e.g., myself (although i generally only use power zones), others, and British Cycling base HR training levels on HRmax, while others do it on ~1-hr TT avg HR.
ric