Run vs Trail Run?

Assuming the 935 is identical to the Fenix 5 with regards the Run and Trail Run apps, the default App settings and data screens are configured slightly differently and Garmin Connect does automatically recognise them distinctly as Run or Trail Run. But the key difference is less obvious and not in the manual; Trail Run inhibits the calculation of VO2 Max and LTHR. (A past implementation on the Fenix 3, as users were frustrated with bad VO2 Max figures calculated whilst running up and down steep terrain etc.)

That's interesting. I wonder if that is the case on the 935.

I can't obviously see how you can manually turn off VO2 Max calculation on the watch however. I understand VO2 Max calculation is also disabled if you don't have GPS on - so won't work on a treadmill for instance.

I recall a recent thread where it seemed Auto Climb may get enabled by default in this mode too so that is another possible difference.

Thanks for the insight on this. I dont do a lot of trail running but some when the weather gets cooler as I live in Atlanta.

Assuming the 935 is identical to the Fenix 5 with regards the Run and Trail Run apps, the default App settings and data screens are configured slightly differently and Garmin Connect does automatically recognise them distinctly as Run or Trail Run. But the key difference is less obvious and not in the manual; Trail Run inhibits the calculation of VO2 Max and LTHR. (A past implementation on the Fenix 3, as users were frustrated with bad VO2 Max figures calculated whilst running up and down steep terrain etc.)

Trail Run inhibits the calculation of VO2 Max and LTHR. (A past implementation on the Fenix 3, as users were frustrated with bad VO2 Max figures calculated whilst running up and down steep terrain etc.)

Wow, that explains a lot - I mostly do trail running and was wondering why I wasn't getting VO2M readings. How did you know that if it wasn't in the manual? Too bad they decided to just disable it instead of reconfiguring the algorithm to account for altitude.

Wow, that explains a lot - I mostly do trail running and was wondering why I wasn't getting VO2M readings. How did you know that if it wasn't in the manual? Too bad they decided to just disable it instead of reconfiguring the algorithm to account for altitude.

Doubt it is that simple. Anyway on most "trail" runs I have done your speed is vastly influenced by not just elevation but what you find under your feet and/or have to swerve round. In other words you are going to go "slow" anyway and so trying to estimate something that is basically a figure that is meant to be for flat and firm road runs seems a bit pointless.

Doubt it is that simple. Anyway on most "trail" runs I have done your speed is vastly influenced by not just elevation but what you find under your feet and/or have to swerve round. In other words you are going to go "slow" anyway and so trying to estimate something that is basically a figure that is meant to be for flat and firm road runs seems a bit pointless.

Agreed. As a road runner/trail runner I was really annoyed to get my VO2Max down every time I went for a trail run with my former F3. It was a great improvement when Garmin disabled that in trail running workouts.

Polar V800 adjusts its running index (something like Garmin's VO2Max) in trail running workouts using the ascent/descent data but with no luck. Suunto disables the running index during trail running as well.

How did you know that if it wasn't in the manual?

It was a welcome change on the Fenix 3 some time ago (see the changelog notes from 7.00 to 7.20 here http://www8.garmin.com/support/download_details.jsp?id=7623) and was quickly verified as being continued through to the Fenix 5.

As it isn't mentioned in the manual, that has caused problems on the Fenix 5 with new users getting all bent out of shape as to why they aren't getting VO2 Max or LTHR values. There are a number of Fenix 5 threads on this issue from angry punters, that usually get to the point where someone will ask them to confirm if they are using the Trail Run app (or worse still have renamed the native Trail Run app to Run, causing mass confusion) and then suggest they switch to using the native Run app; at which point all is well with the world again :D.

Doubt it is that simple. Anyway on most "trail" runs I have done your speed is vastly influenced by not just elevation but what you find under your feet and/or have to swerve round. In other words you are going to go "slow" anyway and so trying to estimate something that is basically a figure that is meant to be for flat and firm road runs seems a bit pointless.

Yes this is exactly the case, even accounting for hilly terrain I am roughly 1 1/2 - 2 min / mile slower on a trail run due to surface as well as obstacles compared to road running. Easier just to disable VO2 Max in this mode and if you want VO2 Max for your trail runs, just configure a copy of the Run Activity and call it Offroad Ru, or Trail2 Run or some other name and then you can have a Trail Run with VO2 Max.

I guess less of a problem on the 935 as "Trail Run" is not a default app. In fact I don't have it enabled at the moment...

I have a fenix 2 and I think it calculates Vo2 max in either "trail run" or "run", I've had it since 2014. I run predominantly on trails and my Garmin calculated vo2 max is ALWAYS low, how do I know? I enter numerous road races during the year and it always spikes up afterwards. During "trail run" periods it will fall to around 45 or 46, but a couple of consecutive races causes it to jump to 51 or 52. I've watched this happen for years and quit worrying about it and just run. I just know I'm "fitter" than the Fenix 2 is telling me.