Good for you for taking the initiative to get tested. Let’s see if I can help you sort out the information the lab gave you. But first thing is to get the semantics sorted out. Exercise science has done no one any favors by not standardizing the nomenclature for many commonly used terms. To wit:
Aerobic threshold (what we call AeT)is defined differently by different sources. But there is enough commonality to make some good assumptions and to be able to translate between definitions. DEF #1: When the blood lactate level rises 1mMol/L above the base line (meaning lowest. Baseline for well trained endurance athlete (especially in a fasted state where I like to do these tests) will be in the range of 1mMol/L. This is where DEF#2 comes from: 2mMol/L. AeT is also often called First Ventilatory Threshold (VT1) because in a gas exchanges test the rate and depth of respiration takes a jump up here. It is also called the Onset of Blood Lactate Accumulation (OBLA) for obvious reasons. And in some literature and schools AeT is called Lactate Threshold. Crazy, I know but this is where some of your confusion is coming from I think.
Now back to your test:
1) Your initial lactate levels were elevated slightly. Were you in a fasted state? Had you have a high carb snack within a couple of hours? Lactates like these, hovering around 2mMol/L in the initial stages would seem to indicate excessive glycolytic involvement for such low intensity work. This could for the reason stated above or because of poor fat adaptation or aerobic deficiency or….
2) How long of a warmup did you have before starting the test? We recommend a 15 min gradual warm up to get the aerobic system firing on all cylinders.
3) How long was each intensity stage? If the test protocol ramps you through the aerobic zone too fast your aerobic system can’t respond quickly enough and will be playing catch up. In order to get a good look at how the aerobic system responds to increases in intensity we like to see 3 minute stages which give the metabolism time to stabilize before increasing the intensity.
4) They’ve set your Z1 upper limit as 123 but your HR never was in Z1 for this test. You started the test at the upper end of what they are calling Z2. I suspect that you are aerobically deficient which would explain why your HR started the test at 147. When you do your personal basic aerobic training what sort of heart rate do you see? Can you train on your steady runs/hike at 125-130.
Regarding your final question about where your AeT is. I’d recommend doing the bulk of your training at and below that 158 inflection point. I’d also recommend conducting an AnT test.
I hope this helps,