Training effect watch wildly inaccurate

BobertBee said:

Walks in my zone 1 heart rate get me a vo2 max or threshold training effect.

Most likely this is because your Max HR is not accurate. How did you determine your Max HR?

• I noticed the past few days that my training load, active calories and daily calories were all very high. I had been ok through beta. 

for some reason in Connect my body weight randomly reset itself after I entered the morning weight and went for a run and walk on treadmill. I entered 95.5 kg for weight and it reset to 121.3 on two consecutive mornings. My watch time also randomly reset from military to 12 hour. What I think is that the very high weight (121) was affecting the algorithm when I ran.

To deal with this I deleted the Connect app and reconnected my Fenix. I then checked my weight and HR Max were correctly set. This morning it seems ok after I entered weight and load, active calories seem to be ‘normal’.

sorry long story but check your body weight entry and HR Max are correct.

My heart rate is set up correctly. I’ve done several full out runs and bike rides to determine this. It used to always get my training effect correct, this is a new issue. I doubt suddenly from one day to the next my HR data isn’t correct anymore. I retest it every few months. It also shows my heart rate in zone 1 in Garmin. So it knows I’m in zone 1, but it still says the training effect is a lot higher. And threshold with a 65bpm kayak trip? You’re not going to convince me that is because my HR isn’t set up correctly. 

The watch doesn't use your heart rate zones to determine the Training Effect. TE is based on Excess Post Exercise Oxygen consumption (EPOC). EPOC is predicted during the workout based on intensity (HR, Pace and power for running and biking) compared to your VO2 Max. That comparison also uses your resting HR.

If the training effect is wrong, it can only be if your VO2 Max, Resting HR, the HR data collected during the workout, or the pace/power data when applicable in runs/rides is off.

Among all the variables above, VO2 Max is more susceptible to be wrong. I call "VO2 Max" the single value point and the model that associates your personalized VO2 with your pace/HR/HRV for various durations. Typically, errors in VO2 Max start with an inacurate  Max HR, or a bias in training (too much focus on some level of intensity).

If your Max HR is correct and this is a sudden issue, I recommend you contact Garmin Support.

I mostly use my watch for low intensity exercises like hiking or kayaking. I do use it for my runs too, and it seems to get it correct for higher intensity runs only. But any low intensity exercise and it’s drastically off. For bike rides I use a bike computer and that one is always spot on. 

BobertBee said:

it seems to get it correct for higher intensity runs only

In your OP, you said it seems to be working better for tempo workouts. I would take this outcome with skepticism as the watch will classify as "tempo" many workouts that don't neatly meet requirement for the other labels.

BobertBee said:

And threshold with a 65bpm kayak trip? You’re not going to convince me that is because my HR isn’t set up correctly. 

If you have spurious HR spikes because movement, wrist HR issues or chest strap dryness, you will get errors in your EPOC estimates.

Were you wearing your chest strap for these activities? How does the HR data look?

If the HR data is correct, then the only possible source of abherent EPOC estimates for non-biking/running activities is that the reference data is off (rest HR, Max HR, VO2 Max estimates).

When all data is correct, the EPOC algorithm is excellent with only about 8% of standard error, per Garmin's publications.

I wear a strap with all exercise. The wrist watch HR is never accurate in exercise. And yes with higher intensity I mean anything above low aerobic, meaning tempo or higher. I guess I’m just going to have to accept that Garmin data will be off. I use Strava and Golden Cheetah as well and they seem to be more accurate in general with the given data. Thank you for all your extensive replies btw. I appreciate it!

BobertBee said:

I guess I’m just going to have to accept that Garmin data will be off.

I wouldn't give up. In my own experience, the metrics are very well aligned with any other metrics from other platforms/software, when applicable (FTP, CP, VO2 Max, LTHR, Treshold Pace, etc.). My training effect is very predictable based on workout design (interval based on power-duration curve).

BobertBee said:

Walks in my zone 1 heart rate get me a vo2 max or threshold training effect

As we discussed above, either you have some bad HR data with HR spikes close to your max HR, or you have the wrong max HR. There is no other possibility for walks, since pace is not used for walking EPOC, as far as I know (only used for running activities). Of course, this is assuming there is nothing wrong with your watch.

What could be wrong with the watch? It could be some software installation issue. To eliminate this possibility, do a backup of your watch, do a factory restore. If you are ready for it, do not connect the watch to the phone for a few days, and do a few workouts with Max HR auto-detection on. This will force a reset of multiple metrics. You might see a change in VO2 max. After your Max HR is detected, do a threshold test to adjust your training zones. If you train across a variety of efforts, including maximal efforts, you will see whether the metrics are lining up better. If not, you can still restore your settings from the backup and get your HRV data back. If you are happy with the fresh start, you will have to wait a couple of weeks to establish a new HRV baseline. Training status will come back within a few days ot training. Up to you.

This is exactly what happened to DC rainmaker. His numbers went crazy. Later he discovered the reason was that his body weight was set to very low (later he discovered it was cased by using a Garmin scale that is also used by his kids and the kid pressed some button that caused the scale to send the kid's weight to his Garmin account)

Thanks. Mine has been fairly ‘normal’ since I corrected body weight. 

I forgot about that article. I’m going to experiment and increase my weight by 10%  for a day and record what happens. The other thing that happened when my weight was wrong was that the Active calories were very very high for the day apart from exercise.