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  • Garmin Connect: “Unproductive” sessions and anaerobic shortage. WTF!
  • Premier Icon markgraylish
    Free Member

    I’m confused (and if I took this too seriously, I’d be despondent…)

    I have a Garmin Forerunner 945 which, amongst other things, can categorise training session results by type of “load” ie anaerobic, high aerobic and low aerobic.
    I’m not following a formal training plan but Garmin is consistently claiming I’m not doing enough anerobic exercise, which I’ve been assuming is time in HR zone 5. However, I’m more of a big diesel engine and I don’t hit max HR easily.

    Last couple of weeks I’ve been dabbling in short Crit races on Zwift (~22 minutes) and I’m getting quite a bit of time in HR Z5.

    Today, however, I did an FTP test and I was in Zone 5 for a good 15+ minutes.

    Yet Connect counts that as zero anerobic benefit and has deemed my status as “Unproductive”.

    Is that just a bug with their software or is an FTP really unproductive (damaging)??
    Or am I mistaken in assuming more time in HR Z5 is benefiting my anaerobic capacity?

    Either way, I’d like to know what type of training sessions I need to do (on Zwift) that provide more anaerobic benefit…
    Short intervals (30 seconds or under) don’t generally provide enough time for my HR to get into Z5 and if I go for longer intervals, my legs tend to run out of power too quickly so I don’t finish 5 hard sprints…

    Premier Icon chrisa87
    Full Member

    Hey; it’s not you. It’s Zwift and Garmin not playing together with those metrics. I think everything you see in Garmin has been pushed out by Zwift. Zwift won’t pay for the license to calculate those metrics and so they’re a 0 all the time.

    Premier Icon rathz
    Free Member

    My garmin watch decides how productive it is based how much time you spend in HR zones. Mine would set the HR zones based on the HR Max it detects. I had to turn the auto detect Max HR off as my sensor sometimes went crazy in the first few mins. It would think a hard 5k was zone 2.

    I’d look at your zones and set them accordingly, maybe change to % of HRR or % of lactate whatver fits better for you.

    Premier Icon mikertroid
    Free Member

    Glad it’s not just me.

    Last week I was ‘detraining’ it bloody well didn’t feel like it!!

    Will look at my HR settings…..

    Premier Icon muggomagic
    Full Member

    I think unless you connect your garmin to the power meter/trainer you don’t get those metrics in garmin connect.

    Premier Icon djflexure
    Free Member

    I think unless you connect your garmin to the power meter/trainer you don’t get those metrics in garmin connect.

    I think this is correct -I am always ‘detraining’ according to my garmin as it only takes into account outdoor rides (as far as I an see – think DC Rainmaker mentions this too). So any TrainerRoad sessions, Zwift etc dont count.

    Premier Icon jameso
    Full Member

    an FTP test and I was in Zone 5 for a good 15+ minutes

    If you can hold that level for 15+, or could do it for 20 mins, then is that really Z5 (90%+)? Not doubting – just an open Q. My LTHR is a bit below the Z4-5 border and FTP is I think a few % below our LTHR. But since I’m not entirely sure of my max I work of LTHR for training levels (or did, ie for what little I do these days).

    Premier Icon ballsofcottonwool
    Free Member

    Your FTP test had zero anaerobic benefit because it was testing your ability to produce power at aerobic threshold when you anaerobic system is only producing a small amount of the total power (it only lasts 1-3 minutes)

    Premier Icon stumpy01
    Full Member

    Nothing to add with regard to the Garmin stuff, but have you looked at the website

    Tons of training metrics for you to wrap your head around!

    Premier Icon DrP
    Full Member

    I think unless you connect your garmin to the power meter/trainer you don’t get those metrics in garmin connect.


    When I train on my turbo, I connect the laptop (zwift, basically) to the tacx and the HR monitor, AND I connect my Garmin Fenix to them as well.

    THus, zwift runs the session, and the watch (and zwift/strava) record… but the garmin is what I sue to assess my training status.

    It’s also useful because a few minutes into a session it will beep up “+2 over baseline” or “-5 under baseline”.
    If I’m running way under baseline, I’ll abandon the training session (my legs would also agree with this…)

    The more i’ve used my Garmin ‘data’, the more i trust it.


    (Currently pleased my VO2 max has slowly climbed to 66… doing the ‘build me up’ workout at the mo)

    Premier Icon markgraylish
    Free Member

    For clarity, after a Zwift session, I get two activities recorded in Connect:
    a) the Tacx > Zwift > Connect
    b) the Tacx > FR945 > Connect
    The Forerunner is picking up the power and cadence from my Tacx independent of the Zwift session (plus it’s own wrist HRM. I also use a chest HRM which is linked directly to Zwift).

    I’m not expecting to see the “extra” metrics that are licensed by Garmin in the Zwift created session but I would expect them to be in the FR945 created session…


    Your FTP test had zero anaerobic benefit because it was testing your ability to produce power at aerobic threshold when you anaerobic system is only producing a small amount of the total power (it only lasts 1-3 minutes)

    Whilst this might be true (I’m no expert so not questioning the logic…), according to the FR945 I was actually in Z5 for 15 minutes in my last TT session (forget that it was an FTP session as Garmin doesn’t know that)!

    So, maybe a better question is:
    How do I bump up my weekly anerobic load without killing myself or over-training or otherwise being “unproductive”…

    BTW: Garmin also massages the ego a little by stating my VO2 max is in top 5% for my age/gender (yay!) and my fitness age is six years below my actual age (yay!) but then kicks you again and tells me I can improve my fitness age by losing weight (193cm and 87kg!) and doing more “vigorous activity”. Sigh 🥺🥺🥺

    Premier Icon markwsf
    Free Member

    Does Garmin use HR as well as power to calculate training effect etc (I assumed it does) ?

    I’ve found that the HR reported by my Fenix is way off that report by a chest strap at higher HR’s. It might be just me, but if that’s the case for you as well then this might drive an under-reporting of the training effect.

    Could you try pairing your watch to your HR strap and see if that changes things?

    Re zones and anaerobic benefit etc I’m not sure but would want to learn more. My thoughts so far though… I’d have thought that given anaerobic isn’t aerobic be definition it’d be based more off power and speed than HR. I know I can/could carry out several short full effort sprints without hitting high HR’s as long as they’re short enough.

    Premier Icon markgraylish
    Free Member


    My chest strap HRM and my FR945 are pretty damn close (usually just a couple of BPM difference at most once I’ve settled into the workout).

    It seems to me that I need to do pretty high efforts (significantly more than FTP) for several minutes before I get into Z5. I’m not sure whether I’m a freak or this is typical.
    In which case, maybe I need to do some longer over/under sessions to increase anaerobic capacity.
    At this stage, I’m not even reaching the bottom of what Garmin recommends:

    Premier Icon markwsf
    Free Member

    Interesting feedback from Garmin to someone asking essentially the same question but about running. Worth a read

    Garmin linky

    Premier Icon DanW
    Free Member

    It is very hard to infer much about highly anaerobic efforts from HR.

    Software tries to fancy things to overcome this but is limited too.

    If you have a fancy Trainer that gives sensible and consistent power data ride to that.

    Main point is don’t let any software heckle you especially when it is bobbins 🙂

    Premier Icon markgraylish
    Free Member

    Hmmm, interesting (not sure whether the responder in that link is just a punter or an expert in this subject…)

    Essentially, it seems that if I want to push up my anaerobic load, I need to do multiple short intense intervals with little warm-up/cool-down as otherwise the warm-up/cool-down skewers the session more towards high aerobic.

    Hmmm again….

    (Also interesting is the revelation that “Un-productive” is deemed anything where your VO2 max reduces. Mine hovers around 53-56 and actually dropped by one point yesterday even though my FTP went up slightly. I really need to RTFM as I don’t understand any of this 😄)

    Premier Icon ofked
    Free Member

    Unproductive simply means that garmins estimate of your VO2max has gone down whilst your training effort has gone up.
    The estimate comes from your power data so if you’re a bit tired or underrecovered it goes down. It’s probably only temporary.
    The performance condition mentioned by DrP is useful – if it comes up as a negative number then there’s a good chance your estimated VO2max is going to reduce if you push on.

    Premier Icon sweaman2
    Free Member

    I have a power meter and I have a Garmin Fenix 5. I find the whole Garmin metric to be junk basically (with the exception of the baseline DrP describes above). For the Fenix 5 at least the VO2 max is just a look-up table based on resting HR compared to Max HR.

    Last week I did a significant amount of riding (staycation) and yet apparently I spent most of the week in “Recovery”. As I got tired my HR went down but nothing in the Garmin seemed to recognize this. (My mountain bike doesn’t have a power meter just my road bike).

    Premier Icon BadlyWiredDog
    Full Member

    I’m not quite understanding why you feel you’re lacking anaerobic power beyond being told that by a Garmin device. Is it impacting on your real world performance on a bike or something you need for a future goal – bear in mind that you’re talking about efforts hard enough that you can’t sustain them for more than three minutes or so.

    If you’re concerned just because Garmin says you should be, I’d maybe take a step back and ask yourself if you really do lack anaerobic performance and if this has a significant impact on your performance / enjoyment of riding.

    Something like the Sufferfest 4DP test would tell you whether your anaerobic power output is disproportionately low and throw complementary sessions at you if it is, but even then, you have to ask it it’s an issue. If you’re a diesel with a big, low-revving engine then it may be that’s mostly how you roll and even hammering yourself with short-duration efforts won’t change that markedly.

    I’m not a huge Garmin fan, which may colour my opinion slightly, but I’d be looking for a more useful source of training metrics unless it’s all just a sort of game, in which case it probably doesn’t matter. Bottom line: what’s your anaerobic power output actually like?

    Premier Icon airvent
    Free Member

    Garmin’s are just a game really, don’t read too much into it and live a happier life.

    Premier Icon v7fmp
    Free Member

    @markgraylish – do you see much of a deviation between heart rates, when using the watch and a strap?

    Reason i ask is i see many people saying the Garmin watches dont read heart rate very well, especially when cycling.

    On a mildly different subject, i use a Garmin 830 bike computer with a tickr heart rate strap. my buddy uses a garmin watch (not sure which model, but cost nearly £700). When we ride together, we have a similar pace, similar fitness (although i suspect i can make more peak power), yet at the end, my ‘load’ is always far far less than his, as is my recovery time. Is this down to dodgy info from Garmin devices, or more likely that we actually have different power/fitness levels which arent overly apparent on a 20 mile shred in the woods?

    Premier Icon dissonance
    Full Member

    Reason i ask is i see many people saying the Garmin watches dont read heart rate very well, especially when cycling.

    I dont think it is just Garmin. Most of the wrist monitors seem to struggle if you are actively using your forearms as you do when mountain biking vs running where they arent so active.

    For the productive/not productive not sure exactly how it works but one issue seems to be it doesnt take the environment into account eg running into a serious headwind and it decides to tell me I am doing badly.

    Premier Icon n0b0dy0ftheg0at
    Free Member

    As much as I like my ride data, I wouldn’t have a clue what my anaerobic zone is by heartrate. I know that a few weeks back, when I was last able to test before giving myself a knee niggle, my Lactate Threshold Heart Rate (top of z4) was ~161bpm according to but anything above is classed as z5.

    Strava calls power zone z6 “anaerobic” which is approx 1.2-1.5x my FTP, which looking at my most recent low end z6 effort up a small incline, was ~3min30sec that left me gasping at ~178bpm, just below my typical max of ~185. Top end was ~30secs, having had ~30secs recovery from that low end effort… Hardly spectacular figures, just giving context to what that zone means for me at the mo.

    Premier Icon markgraylish
    Free Member


    Reason for this posting is I assume that Garmin and First Beat are considerably more experts than I am on the subject of training so I’m taking their results at face value!

    Connect suggests an optimal training load (see my screen shot above) and I’m trying to determine what type of riding I need to do to get me into the optimal range for anaerobic benefit.

    Do I lack anaerobic capacity? I’m not sure but I definitely get out-sprinted by my otherwise similarly fit (and similar weight) riding buddy (though I am somewhat older than him). He can definitely suffer more than I can…

    I’m also out-sprinted most of the time I race on Zwift so I’m curious why, when I did what I consider a reasonably long, max effort session, Garmin tells me (a) it was un-productive and (b) somehow it had zero impact on the anaerobic.

    Given a choice of two training methods, HIIT or more endurance focussed, I’d much rather do HIIT as,frankly,I don’t have the mindset to sit on a turbo trainer for hours on end doing low intensity stuff (and, where I live, the roads are conducive to that type of riding either).

    Anyway, I’m no pro so none of this really matters in the real world other than my dislike of being “left behind” by faster riding buddies (and my refusal to acknowledge that I’m getting old and decrepit!)

    Premier Icon markgraylish
    Free Member


    I have a Wahoo Tickr chest strap HRM as well as the Forerunner.

    I find that the Tickr takes some time (a couple of minutes) to “settle down” as it initially over-states my HR (eg when I first put it on, it reads something like 140bpm even though I’m standing still) but once it settles down, the Forerunner and it are very close.

    Im so sure about how the Forerunner handles mountain biking though as that involves a lot more wrist movement than road biking or turbo training…

    Premier Icon petrieboy
    Free Member

    Possibly not directly related to the OP as it’s running based but my fenix6pro is happy if I pretend to listen to her but gets in a proper strop if I dont.

    Select run – she pipes up and says “I think you should do base blah blah for 22 minutes” but I’m just going for my normal jog so say nah, I’ll just jog my normal route at my normal pace and not do your workout. Thanks for the offer tho. Get to the end of the run and she’s giving it all “well that was totally pointless you might as well have had a MarsBar and watched telly for all the good that did”

    But then the next time she’ll say exactly the same at the start of a run and I select “go on then, I’ll do your workout” but then run exactly the same run at the same pace as I would have done anyway but this time at the end she’s all “wow that was amazing petrieboy you’re so strong and handsome and athletic is that a new shirt, it looks great on you”

    Mleh – technology!!

    Premier Icon rugbydick
    Full Member

    It’s all rubbish… but I think the point about warm up/down skewing things could be correct.

    Last night’s run was short hill intervals (all intervals at max effort / anaerobic, with a chest HR strap):
    – 2km warmup
    – 4×90 seconds
    – 4×60 seconds
    – 4×30 seconds
    – 2km warmdown

    According to my Garmin 945 that impacted “Base” fitness and my training of short on Anaerobic effort.

    Premier Icon BadlyWiredDog
    Full Member

    Given a choice of two training methods, HIIT or more endurance focussed, I’d much rather do HIIT as,frankly,I don’t have the mindset to sit on a turbo trainer for hours on end doing low intensity stuff (and, where I live, the roads are conducive to that type of riding either).

    I don’t think anyone does. My take – and I’m not a coach / expert etc – would be to do some proper short, savage, intervals. Eg: do three sets of 5 x 20 second all out sprints with 40 second recoveries and around five minutes between sets for a couple of weeks, then up that to 5 x 30 seconds with 30 seconds recovery. Do that two or three times a week and you should improve your anaerobic capacity noticably, it won’t just help with end of race stuff, it’ll have all-round benefits and actually works really well for mountain biking where you need to hit technical climbs hard then recover. If you’re outdoors use a gentle, constant gradient climb and go absolutely flat out, recover as you roll back down then repeat.

    I have no idea if Garmin will approve, but it’s a classic sort of session and works for me. HTH.

    Premier Icon matthewlhome
    Free Member

    In response to the OP, looks like zwift etc now included in training status so should get more productive Dcrainmaker explainer

    Premier Icon markgraylish
    Free Member

    Hmm, that Zwift > Garmin update may help…guess I’ll find out when I next do a high intensity workout.

    May also try BWD’s suggestion to see what impact it has on my numbers

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