Forerunner 265 Training Effect (=3.2) differs significantly from that of the Forerunner 235 (=2.4) during the same "run".

.

No; why would I use chest strap when both watches have monitors...  Thanks for the reply, but it was a little short on explanation.

Over 100 views and, yet, no relevant answers after 5 days...

Bc you are asking a question that nobody can answer meaningfully and definitively.

Does your FR265 (released 2023) do some things differently than your FR235 (from 2015)? Yeah, probably.

None of us (i.e. ppl who don't work for Garmin) knows exactly how training effect is calculated, so nobody can really give you a definitive answer here.

For all we know, the algorithm actually hasn't changed since 2015. Or maybe it's changed a lot. I have no idea. Unless Garmin wants to tell us, we can't know.

Even if someone came out and said "yeah, it's different and better on FR265", how would that help you? If they said "no it's actually worse on FR265", would you return your FR265 and hang on to your FR235?

rrellio said:

I'm guessing that the 265 value is more accurate

What does more accurate mean tho? Compared to what? Training effect is just a number made up by Garmin/Firstbeat. There's no external, objective physical measurement or industry standard formulaic metric to compare it to for the purpose of determining "accuracy".

Maybe you could argue that the one device's value is "more useful" or "better" than the other's.

rrellio said:

I've been tracking run data in an Excel worksheet since circa 2011, and I find it useful to compare TE reductions over time.  It appears, however, that I'm not going to be able to compare old / recent 235 runs to the newer 265 runs.

If you want to compare this kind of thing in a device-agnostic way, you can use runalyze.com, a free 3rd party website that syncs with Connect. It calculates TRIMP (training impulse) from activity HR and duration. However, this value is more akin to Garmin's Training Load, as opposed to Training Effect.

You could also look at relative effort in Strava (subscription required), but again this would be more akin to Training Load.

rrellio said:

Got new 265 a couple weeks ago and have been walking 5k while also wearing the 235. 

Is the HR data recorded by FR235 and FR265 similar when you look at it in Connect? Not only do those devices have different optical HR sensors, you are also wearing both watches at the same time, which means the one or both of them may not be positioned optimally. So the 2 watches may not even be recording similar enough HR data for the algorithms to provide similar results.

This might explain why 3351229 asked you whether you you wear a chest strap for these activities. At least if you wore one chest strap and paired with both watches, you would be more or less guaranteed to be feeding the same HR data to both watches.

You could even broadcast HR from one watch (like the FR265) and receive that broadcast on the other watch (FR235), so that you'd be using the newer (and better) optical HR sensor for both devices

Do you have the same max heart rate set on both devices?

There's other things which could explain the difference, besides the training effect algorithm itself.

Finally (haha), a reply with some substance.  Thank you!

flowstate said:

Bc you are asking a question that nobody can answer meaningfully and definitively.

Maybe, but I'm not the only person in the world to wear two Garmin watches at the same time for comparison purposes.  My reasonable assumption, therefore, was that the question had probably been asked / researched before.

According to Firstbeat website, TE is calculated based on a "heart rate-based model".  During both test-walks, 235 and 265 HR data was similar (within expected tolerance of a few bpm).  Yet, TE difference was huge (percent-wise).  265 was higher both times.  Seems odd, since the value is largely based on HR. HR on both watches agrees.  Got to run now, (no pun intended), but will send another reply later.  Thanks again!

I'll check out runalyze; that may actually be the best solution.  During the last outing (Monday), I ran 0.1 miles during the 5k walk just to test out the knee.  That was the the 3rd use of the 265.  I didn't wear the 235.  Maybe the 265 needs to perform some "learning"...  The 265 TE value has gotten lower each time (1st outing:  3.6;  2nd outing:  3.2; 3rd outing (Monday):  3.0).  Corresponding max HR's were 148, 148 and 155, respectively.

flowstate said:

Is the HR data recorded by FR235 and FR265 similar when you look at it in Connect?

Yes, +/- 4 bpm for average HR, and +/- 2 bpm for max HR.  I also compared old 235 HR (LH wrist) to RH wrist data and they were in same ballpark.

flowstate said:

Do you have the same max heart rate set on both devices?

Yes.  It took me a while, though, to figure out that the 265 can only be set via the app.  235 can be manually set on Gamin Connect.

My plan is to go for another outing tomorrow before weather gets bad this weekend (I'm in Atlanta area).  It will be interesting to see if the 265 TE falls more in line with a walk (with 0.1-mile run segment).  BTW, I'm no longer a spring chicken, so those HR values might seem high to some.  :)  Thanks again!

Did you have a look at this page?

https://www.garmin.com/en-US/garmin-technology/running-science/physiological-measurements/training-effect/

"Aerobic training effect is the same as the original training effect feature offered on many earlier Garmin watches, except the scale has been modified slightly to account for — let’s face it — those really short or really easy activities that have no meaningful training effect. In other words, we added a “0” at the bottom of the scale."

Thanks.  Yes, I previously saw that page.  However, the analytics to calculate a TE of (an actual) 1.0 thru 5.0 would not have likely changed.  Those that previously received TE of 1.0 would likely have fallen in the range of 0.0 to 0.9.  Those that previously received a 3.0 would still receive a 3.0 if the inputs were in the same.