Garmin estimate of lactate threshold? | 80/20 Endurance

Garmin estimate of lactate threshold?

Viewing 6 posts - 1 through 6 (of 6 total)
  • Author
    Posts
  • #6864
    nradov
    Participant

    Is the Firstbeat analytics estimate of lactate threshold heart rate as implemented on Garmin wearable devices accurate enough for setting zones on your run training plans? I recently completed your 10k level 2 heart rate plan and did all of the workouts for the full 12 weeks. I used your zone calculator with LTHR = 177 bpm as reported by my Garmin Forerunner 935 (including HRM-Tri chest heart rate monitor strap). At the end I did slightly improve my time on the next race, but I think that was mostly from pushing harder and I didn’t get significantly faster at a given heart rate. The race itself was actually an 8K (not 10K) and I finished in 35:30 (7:06 min/mi pace).

    When I showed my Strava workouts to a local coach he was concerned that my heart rate was way too high during Zone 1 – 2 workouts and thus I wasn’t getting optimal mitochondria and capillary development. The 80/20 calculator shows Zone 1 = 127 – 143 bpm and Zone 2 = 143 – 159 bpm but the coach suggested I should focus on staying under 130 bpm during easy workouts to better develop those energy systems. My heart rate has always been somewhat high: resting rate is about 56 bpm and I sometimes get up to 199 bpm at maximum effort.

    So at this point I’m confused on how to proceed. Can I trust the LTHR number on my Garmin? Do I need to get a real LTHR lab test? Or is it better to forget about LTHR and go with pace zones instead?

    #7800
    David Warden
    Keymaster

    N, apologies for the late reply, your post got caught in a “pending review” which I did not know our forum had. A few posts have been delayed quite a bit!

    I think you and I may have already corresponded on this topic privately anyway since then? Let’s see if I give the same answer twice, yes?

    Garmin’s estimate of LTHR is just an estimate. It can’t replace lab and field test results for accuracy. Frankly, the field tests we prescribe in our document Intensity Guides for Running are exceptionally close to lab testing (and free)!

    Your Garmin *might* be right at 177, and for some people it is. But no, I would not trust it. Perform the field test from the document above or a lab test to get a precise number.

    Additionally, yes, Pace is for the most part more reliable than HR. With a few exceptions, I recommend Pace over HR to measure intensity (but you can always use both at the same time).

    It’s refreshing to hear a coach actually encouraging athletes to slow down! Your coach is a rare find, keep him! I’m quite comfortable with our zone system, and Zone 1 and 2 as defined to maximize aerobic benefits. However, this is assuming that your LTHR is really 177, yes? It might be lower or higher, and therefore maybe your HR Zones are indeed wrong. Perform that field test (and report back to us here).

    David

    #7814
    nradov
    Participant

    Thanks for the explanation. My local running tracks are closed right now so it’s difficult to do an accurate time trial, but I do have data from an 8K race on a flat course a few months ago which should be pretty close. My race finishing time was 35:30. Over the final 20 minutes my average heart rate was 189 bpm. According to the TrainingPeaks analysis, fastest pace over 30 minutes was 7:06 min/mi.

    So based on that data I’m still confused about what my zones should be. If my correct LTHR is actually 189 then the zones should be even higher: Zone 1 = 136 – 153, Zone 2 = 153 – 170. If I do more workouts in the 130 bpm range as the local coach suggested then that wouldn’t even get me into Zone 1.

    #7816
    nradov
    Participant

    Also if my LTHR really is 189 bpm then my Zone 5 would start at 198, which is basically the same as my max heart rate. Does that make sense? It seems quite high.

    #7827
    David Warden
    Keymaster

    N,

    Yes, I would use 189 as your LTHR for sure based on that peak 20-minute HR.

    The 80/20 system is based on the empirical evidence that elite athletes spend 80% of their training “easy,” and we define “easy” as less than ventilatory threshold. Since ventilatory threshold is difficult to field test for, we use lactate threshold (using HR, Pace or Power) to approximate lactate threshold. When we designed the 80/20 Zone 1, it was not based on empirical evidence: it was based on our best guess of the lowest level of training we felt an athlete should maintain when exercising. However, theoretically, “Zone 1” could be much lower then our current base Zone 1.

    The bottom line is this: you are still following the 80/20 principle if you are below Zone 1 when the exercise calls for Zone 1. As long as you are not walking, you are exercising at an “easy” pace and supporting the 80/20 protocol for that workout segment. Particularly for athletes with unusually high LTHR (like yourself) it may be that our Zone 1 floor estimate is too high. Feel free to hover at 130 as much as you want when Zone 1, and even Zone 2 are called for. Then, just go hard when the exercise calls for the moderate and high intensity!

    Your upper level actually falls within the predicted range. Zone 5 is the maximum pace you can hold for up to 60 seconds, which is maxHR intensity.

    Also, consider switching from HR to Pace or Power as your primary measure. As I’ve pointed out so often, HR is unreliable. It may be that you are more likely to maintain 80/20 zones using the more consistent measurements of Pace and Power.

    David

    #7872
    Charles
    Participant

    I’ve found that the Garmin estimates change somewhat often for both LT and VO2max as I move to different phases and plans of the 80/20 system. I suppose it to be the results of the Garmin algorithms. I’ve abandoned their estimates to avoid being “whipsawed” by the frequent adjustments.

    I prefer to use the 80/20 calculators and tune-up races. I run roads, and finding a level stretch is not easy and I don’t know that an estimate from a track is better for my situation. Regardless, the calculators have provided estimates that correlate well for heart rate and pace up to threshold efforts.

Viewing 6 posts - 1 through 6 (of 6 total)
  • You must be logged in to reply to this topic.