If you read the paper, a dfa-a1 = 0.75 is already beyond LT1 and VT1. I personally use dfa-a1 = 0.8 as my threshold.
Here’s some crude graphs from a workout this weekend where I wanted to measure LT1 and estimate VT1. I used 10-minute stages and collected blood lactate, muscle oxygen, and breath data. Nothing too exciting except for the blood lactate vs dfa-a1 data.
The first chart has dfa-a1 data from the Runalyze script.
Here’s Altini’s script in Golden Cheetah
For me, first lactate turnpoint is about 165-170 watts. dfa-a1 = 0.8 is about 167 watts. Good enough for government work.