Why is my Lactate threshold pace going up while the LTHR is going up as well?

A lot of training around threshold, and not enough long slow distance to train the aerobic base?? Not enough info to conclude this, but it would be one plausible way to get that kind of result.

Well you're right. I routinely have high aerobic overreach and low aerobic insufficiency. Incredible how you guessed it. Can you enlighten me on how that leads to this?

Is there anything good about the results though? Is the higher lthr at least sth to celebrate and the rest to be fixed? 

hi mate. it depends on vary  functions.  your training method , your recovery time, your nutrition and ...

i suggest you , first do a blood test to know your hemoglobin rate because hemoglobin has a grate role in oxygen blood. then i suggest some supplement to increase your indurance . 1 houre before going to activity take at least 4-5 grams of Beta Alanine  and 4-5 grams of L Arginine         they help you to improve your blood circulation and prevention from fatigue . and at the end i think you should do a fitness test to know if you have a problem or no. 

This really gets into the area of training rather than technology.

But the short version is that the body has a range of energy systems, and to truly run fast, all of these need to be performing well. but to improve these systems, you need to train each of these systems independently.

By focussing on threshold/high aerobic runs, you have been developing your body's ability to process lactate, which is important for maintaining threshold. Hence the increase in LTHR.  But in neglecting the aerobic system, your body's ability to process oxygen and run at a moderate pace has declined, and so has your threshold pace.

Long Slow Distance to develop the aerobic energy system is really the key to running faster. Running slowly to run fast may seem counter-intuitive, but by increasing your ability to cruise efficiently using the aerobic system only, means once you add the lactate and anaerobic systems back in, you are faster overall.

The aerobic system is the cake, and improving your running at lactate threshold is just the icing on the cake that makes it look good. And the anaerobic system is just the cherry on top. But without the aerobic cake underneath, you are just left with a gooey mess on the baking tray. 

hmm, cake. 

Most of your running should be at 60-75% of maximum heart rate, with perhaps just one day per week at threshold.

I am grossly oversimplifiying all this, of course. But there is plenty of low hanging fruit to be had in some more balanced training, before reaching for supplements, or needing any bloodwork done.

So, in zones 1 and 2? Or is 3 also aerobic?

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Thanks man, you're amazing for putting the effort to give me so deliciously painted details on what's likely going on for me. 

Lemme share with you, I am mostly training as per the 5k plan, for second or maybe third time, depends on how I count. The thing is, it gives me a lot of easy and long easy runs, but those runs ain't easy, they are at my threshold. I should probably just set up a goal that would make the easy runs be at a pace that matches the 60-75% (zone 1, 2) for me. However, I got attached to the idea I'd run it in 25 minutes and the "confidence" bar was high, so I thought I'd just push through. But as per the garmin training plan I basically had almost no low aerobic training.

If I do a "suggested workout", not the one from plan, then it's better — it doesn’t care about pace, but it tells me to maintain 145 BPM, which is the low zone for me. And that is at around 7:20 min/km. I felt so sad about having such a slow slow speed for low aero and really wanted to reach the 25 min goal, so I kept on going as per plan, but it looks like I just have to bite the bullet, maybe cancel the plan and really pay attention to having plenty of low aero. 

I already read about it somewhere, but I just couldn't believe my VO2 max would drop continuously so low. Now I feel sad about being so stubborn — it looks like I was training so innefficiently I actually kinda ruined my fitness. 

I'll start doing a lot of low aero and hope to see the measures go back up. And fingers crossed that the amount of high aero I did will pay up later.

I'm buying a bike now. I wonder, if doing a lot of low aero on the bike would also fix up the cake for me.

Your heart doesn't know whether you are running or cycling. Actually, cycling aids in keeping the HR lower since part of your body weight is supported by the bike itself.

I did run 5K in 22:30 two weeks ago, but like you I struggle to keep my HR low even on easy runs (I am on average at 155 BPM at 6:30 min/km). Lots of long activities in the Z2/Z3 should really help building the required aerobic base (which is what you mostly use in the 5K - and longer - races).