Training Effect

I have similar experience. I can get rarely some anaerobic TE even running in Z5. These are my data from today's trail run. My HR zones are correct (I am 51).... 

Check out Firstbeat papers on how they calculate anaerobic training affect. 

Basically, simply running at or above your anaerobic/lactate threshold isn't sufficient. What they are looking for is up/down bursts in intensity, i.e. your heart rate shots up to and beyond LT, then drops off as you recover. The idea being that the anaerobic energy system is only active for the first 2-3 min of high intensity effort, then it is complemented by aerobic system.

Hence, to get maximum anaerobic effect you would have to run shorter intervals 1-4 min duration, but with higher intensity. 

Also, I see that most of your high effort was in Z4. The Firstbeat anaerobic effort kicks in around LT, which would probably be at the boundary, or fairly close to Z5.

thanks Nick for this, it makes sense

I don't know if I have to agree with how firstbeat calculates his anaerobic training effect. In my opinion the workout that should improve the most the anaerobic performance are intervals of 200-300-400 meters, but they are so short that is difficult that heart rate grows high in Zone5. So if I want to have a high anaerobic effect in the way Firstbeat is computing it, I should do intervals at least 1-2 km long but faster than I usually do this long intervals. I'm not 100% sure that my training would benefit doing 1 km interals so fast: in my opinion it would be too fast and it could be counterproductive, because I would become tired too early and I wouldn't do enough intervals and a good training session. It would be nice if Firstbeat could give some real examples of workouts with a high anaerobic effect. Till now the maximum I could get is 2. I must admit, I agree usually with aerobic training effect, but I'm a little skeptical with anaerobic training effect.  I began not to watch at it any more, even if the watch says that my training lacks of anaerobic training.

In my opinion "base" for that type of workout is simply wrong. In my opinion unfortunately with the new TE metrics Garmin and Firstbeat introduced some bit more confusion

today did 6x30s all-effort-run and I got 

Training Effect

Ah, too short! 30 sec bursts would involve ATP/CTP energy pathway, not anaerobic. Hence, no anaerobic benefit. Also, 6 sprints, unless you did an adequate warmup and got your heart rate into Z4, close to LT, wouldn't amount to much, aerobic VO2 Max or anaerobic.

Here's a short sample of workouts and expected values from Firstbeat:

https://www.firstbeat.com/en/anaerobic-training-effectworkout-explanations/

Here's the paper I referred to above:

https://assets.firstbeat.com/firstbeat/uploads/2015/10/FFW609US05-171.pdf

Basically, Firstbeat uses "anaerobic effect" in its strict scientific definition, i.e. impact on anaerobic energy pathway. The energy system that power high intensity efforts of short to medium duration, i.e. from about a minute to 3-4 minutes. Anything below 30-40 sec is handled by the cell's primary energy source -- ATP and its cousin CTP. Anything longer than 4-5 minutes would see regular aerobic system kick in and complement and eventually take over completely for longer efforts.

Make sure your max heart rate and LT are set correctly. Better still, anchor your Z5 at LT. For example, my MHR is about 182. My LT is around 163. This is the beginning of my Z5. Every time I do a heavy bag workout with bouts of about a minute followed by 30-60 sec recovery, or high box jumps on a similar protocol, or hill intervals I get a non-trivial anaerobic TE.

I didn't read the whole paper of Firstbeat, but the samples of workouts of Firstbeat makes sense. I see that with 10x400 m @VO2max pace they expect a anaerobic training effect between 3 and 4, and I agree with this. But on 7th september I did a similar workout 4x600 + 4x400 and I got a aerobic training effect of 3,2 (and this matches my feeling) but  only a anaerobic training effect of 2, that is too little.  I wanted to do other intervals of 400 meters but I had to stop because I was too tired. Maybe there are two reasons:

1 - perhaps my watch calculated a VO2 max that is higher of my true value

2- my watch gives always a wrong temperature in Garmin connect. I did intervals with 30°C and GarminConnect and the watch showed a temperature of 10°C. Maybe the heat played a roll in my negative performance, and the watch coudln't take in account the heat for computing the right anaerobic training effect.

Another workout I did was 5x1 km on the 30th of July. The watch gave 3,2 aerobic TE and 2,2 anaerobic TE. In my opinion anaerobic TE was too low .

I know that you could say that I should do the intervals a little faster, but in my opinion if I tried to do it faster I wouldn't manage to do it. For me they were really hard at that speed, I doubt I could do it faster.

Try the following

- Before each workout, open the connect app and do a quick sync with the watch, that way the watch can take the real temperature and hopefully fix those issues u are seeing :) 

- Also, if you keep the app open in the phone ( in the iPhone is called background app refresh ) the watch can stay connected and hopefully update the weather while you are working out :) 

Unfortunately there is an issue with the weather station that Garmin uses to calculate the temperature. If I move in another town, it's enough 30 km away, the temperature is correct in the watch and in Garminconnect. But in my town the big number of the temperature is always wrong (15°C under the real temperature), although the forecast for the day and for the week  are correct. Strange no?

I emailed Garmin Support and Garmin beta team, but unfortunately no answer. I also opened a thread in this forum, with the title "Wrong temperature in Garmin Connect".