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Garmin Forerunner 935 increases the stress level !

Former Member
Former Member
Hellol!

Garmin Forerunner 935 increases the stress level against Vivoactive 3. I make the test 3 days.
Restart to factory settings, remove apps, send to service. No solution. Garmin Forerunner 935 does not work right.

Do you have the same problem? I'm looking for a solution to the problem... !? ciq.forums.garmin.com/.../1312844.jpg ciq.forums.garmin.com/.../1312845.jpg
  • The VO2 max calculation doesn't take account of climbs

    According to the Firstbeat papers it does.
  • The VO2 max calculation doesn't take account of climbs


    According to the Firstbeat papers it does.


    Yes and no, afaik. The VO2Max calculation is supposed to get rid of automatically non-representative data, which is supposed to include climbs/descents (and also includes things like: stopping at red lights and resting between workout intervals). Reading between the lines, this is done by ignoring data where the combo of speed and HR deviates too far from your current fitness. It does not take account of climbs the way you'd expect, by trying to calculate some sort of "grade-adjusted pace" based on elevation changes, which wouldn't work on all Garmin watches (supporting VO2Max) anyway, since not all of them have barometers. Compare this with Garmin Running Power, which requires a barometer in order to "properly" account for elevation change.

    This has been confirmed by HermanB (FirstBeat rep) on these boards. When someone asked him if elevation changes are taken into account, he said (paraphrased): "Yes, but not in the way you might think. Non-representative data is automatically discarded by the FirstBeat algorithms."

    Many people have noticed that if you start your run off with a steep uphill section, your performance condition will be lower than expected. In the same vein, I asked HermanB if running a 10k downhill race (for example), would produce a "better than expected" (i.e. "false") performance condition and he basically confirmed that it would, but it would not affect your VO2Max because it would be outlying data.

    https://forums.garmin.com/forum/into...ance-condition
    Yes, if you go for a 10k run that is all downhill... then, ceteris paribus, yes, I would expect you'll have a higher than usual positive (+) Performance Condition - certainly during the earlier parts of the race. You are running faster than normal with less effort. So that's the first part. You could expect to get a similar result if you were running with a strong tail wind. Upon several occasion I've, personally, seen a few points difference in Performance Condition between running into the wind or against it.

    How does this impact your VO2max? Well, that's a little trickier. Other than when you first start using your device, your VO2max calculation is never based entirely on a single run. So, unless you're always, only, running in downhill races (highly unlikely), your watch will likely recognize that particular as being non-representative and take that consideration into account as it looks to see if your fitness level has actually improved.


    So that's not really taking climbs/descents into account, per se. It's just saying that unless you're going uphill/downhill all the time, that outlying data is actually going to be ignored. FirstBeat doesn't "know" that you're climbing/descending a hill any more than it "knows" you're running with a head wind or tail wind.

    But as a matter of fact, someone in another thread reported temporarily changing training locales from mostly flat to mostly hilly, and their VO2Max went down as a result. When they went back to flat terrain, their VO2Max went up. This makes sense because it would take several hilly runs to trigger the change, not just 1 downhill race.

    If VO2Max calculations truly took climbs/descents into account, then I would've expected that person's VO2Max to stay the same (assuming their true fitness stayed the same, over that short period of time). OTOH, say VO2Max were based on Garmin Running Power (which is adjusted for elevation changes) instead of pace (which is not), then I wouldn't expect to see dramatic changes in VO2Max just by changing your routes from flat to hilly.

    A quick personal example: I live on an island in Helsinki, and for the past few months it's been blistering cold, the sea is frozen over, and every running track in my neighborhood has been packed with snow and ice. (fun, right? Finland is splendid in the Summer, but completely absurd in the Winter). With the right clothing, shoes, and a flinty attitude, you can still go out for a run. Obviously, these are some pretty tough conditions. As expected, eventually my watch decided I was losing fitness (dropped a couple VO2max points - when based on what I was doing and feeling, I was almost certainly gaining). Then yesterday, finally, a good portion of the paths cleared. Went out for a 30 minute run and finished with a Performance Condition of +5... am I fitter than I was 2 days ago? Was I particularly well-recovered? No, but you can run a lot faster with less effort when you're not running in snow and ice.


    IOW, FirstBeat VO2Max calculations don't know that you're running hilly or flat any more than they know you're running on snow/ice versus clear pavement/roads.

    That's my understanding of it, anyway. Hopefully I'm not misunderstanding what was said.
  • Thanks, that's interesting. It isn't so obvious with vo2 but I constantly ignore the lactate threshold values/speeds where they have kicked in on an uphill section.

    The only way to get a sensible figure out of them is to find a flat place and do the guided test.

    I had the stairs thing kick in yesterday also just walking round to the shops so seems like something isn't right.
  • That's my understanding of it, anyway. Hopefully I'm not misunderstanding what was said.


    It's not you. It's me.

    Great job piecing all that together. Very well mapped out.

    That said, in trying to make the greater point about identifying representative data based on speed and HR, I omitted a key point.

    It isn't absolutely necessary - but when available from a device, change in elevation data is fed into the Firstbeat analytics engine to enhance the reliability of the calculation.



  • Well that’s what I get for running my mouth :p. Thanks for clearing that up, and sorry for muddying the waters.