The way the Lactate threshold data is plotted on Garmin Connect is buggy. As you see in the attached picture, the LT-HR is plotted on top of LT-Pace but the graph ranges make absolutely no sense.
LT-Pace: the graph range is from 2:15 to 13:25 min/mile pace. Who on earth (other than Bolt) runs close to 2:15 min/miles?!? The result of this *buggy* graph range is to make the blue pace line to look completely *flat* conveying no information. The pace graph range in my case should be more between 6 and 8 min/miles so that the variation is visible. My actual LT-Pace is currently 6:29 (as stated under Most Recent) but how can you even see that on the plot?
LT-HR: the graph range of HR on the other hand is between 166 and 171! Yes, that's just 5 bpm range! this makes the graph look as if there is a huge variation of the HR but in reality we are talking about a couple of bpms! This is the exact opposite of the LT-Pace graph, here the range is too small so that minute bpm variation look huge!
It's clear that whoever designed this graph and range calculations has made some mistakes leading to this unusable plot.
This has been going on for months and I was just fed up with Garmin not fixing this especially since I am using a $500 735xt to capture the data.
PS
Don't even get me started with how the same graph looks like on Garmin Mobile! There the LT-HR plot uses piece-wise step approximation (instead of the linear used on the web) making the HR looking like a staircase. Seriously!