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Threshold TE for activity 80% Z2/3, differs from 530?

Back from a ride this morning, checked the TE stats from both my 945 and 530.

First odd thing is the 945 TE reads higher, despite sharing identical HR settings to the 530. Both items connected to the same HR (Polar H10).

Second odd thing is, a 4.9 Aerobic TE for 2hr ride where 80% was Z2 & 3. My ave HR for the activity, as recorded by the 945, was 133bpm. My Z2 for Cycling is 126 - 138bpm, Z3 is 138 - 150.

First question - why would the 945 and 530 differ so much when they're getting HR from same source, and using same HR zones to calculate TE? Surely both device f/w share same code for something as basic as TE calculation.

Second question - does the 4.9 Aerobic TE seem to correlate with the ave HR / ave HR zone? I'd have expected to have been pushing mostly Z3 / Z4 to get that TE rather than averaging middle Z2.

945 is f/w 7.2, 530 is f/w 8.00.









  • For Cycling, power counts a lot.
    If it was a bet, I go with power impacts TE for cycling more than HR.

    Are your power zones equal between devices?

    From your screenshot, you spend a reasonable amount of time above Z3 of power. So, from my understanding, those TE make sense.

  • The TE calculation uses power rather than HR if it is available.

    And from your screenshot, with an IF of 1.087 for 2 hours of riding, your FTP settings are off. Way off. Especially if you think that you were riding zone 2 & 3 by HR. An IF of 1.00 should be what you get from riding at FTP. Doing 2 hours at FTP is impossible.

    So the TE results will be off accordingly.

  • I guess I was under the assumption like you that HR ws the driver of the Training Effect info... but... with your crazy high TE for low HR, and the high power zones you show... i'd say Power is taken into account.  I did a 2hr trainer ride this weekend at Aerobic TE of 4.4 with a lot of tempo/threshold 10min blocks.  Plenty of zone3-4 HR - avg 149bpm (77% of max).  But not much zone 5, 6 power.  IF 0.86

  • Thanks, have dug deeper into what makes up TE and it's HR and power for cycling rather than HR and speed for running. My power zones are untouched / default % of FTP so will see if they need tweaking. HR and power zones are the same across both devices. 

    I think the reason for the initial difference in calculation of TE across both devices is the 530 hadn't been switched on or sync'd since my last ride, so had my load as of that ride (pretty low) and didn't include the load from a week or running and swimming (945 load currently showing as 1,219).

  • Looks like for some reason my FTP on my 945 was off - 248W rather than 262W on my 530. Not sure how or why as everything else - HR and power zones - appear to be sync'd between the two. Just checked the IF from the activity recorded on my 530 and it''s showing as 1.031, my 530 is now showing same FTP as my 530.

  • If your HR zone 3-4 equates to an avg 77% max, what's your Z4 & 5?

    My cycling HR zones are based on max (172) with Z1 as 68-73%, Z2 as 73-80%, Z3 80-87%, Z4 87-93%, Z5 93-100%. 

  • yep, your zones are significantly wrong.

  • Not sure if reply was to my post but if so, what's recommended for cycling HR zones?

    I've set my running zones as these, using max 178bpm: https://www.myprocoach.net/calculators/hr-zones/

    For cycling I've used the same zones with max 172bpm.

    Admittedly I've not checked my max HR for around 18 months but I doubt it's changed that significantly.

  • do a 30 minute MAXIMAL effort for each sport 

    your LT2/LTHR is approximately an average of the last 20 minutes

    base your zones on LT2 not HRmax/Hrrest

  • I think the default will get you most the way to where it should be for a 'typical' situation.  If you are doing specific workouts and targeting specific HR ranges that are outlined by a training plan/coach... then getting all fancy/custom might be good.  Max HR shouldn't change much over just a couple years, I have seen things pointing to very active people MaxHR doesn't change much at all over the years.  

    I think the main thing I was seeing as a problem (and others) was that likely your FTP was set low likely.  You had tons of time in high power zones... yet HR was in low zones.   55minutes in vo2max and Anaerobic!  If you are a pro rider... I suppose with a huge base... could accumulate that much in zone5-6 over a very long session of intervals and HR might stay low w/recoveries... but then your FTP would be MUCH higher! LOL

    In general for a longer ride with much of it at sustained efforts, if in pretty good shape aerobically your Power Zone bar graph and HR Zone bar graph should be fairly similar.  If you are doing a lot of hard intervals with longer recoveries over the 2hrs, then due to HR lag you can see discrepancy.  Having time in high power zones that adds up with a bunch of reps, but with the short duration HR never gets elevated much.