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Anaerobic Primary Benefit - Is it necessary to reach Z5?

9745928
9 days ago

I believe that Garmin does not give you anaerobic effect in a running activity if you do not reach Z5. Can anyone confirm or refute this?

I have a Garmin FR 255 and use a chest strap HR sensor.

On my Garmin profile:
MHR: 191
LTHR: 170
Z5: >172 (90-100% of MHR)

I can usually obtain anaerobic primary benefit when doing sprint/hill repeat intervals (about one minute fast and one minute walk), but there are many times Garmin gives me high aerobic primary benefit instead. I believe that Garmin doesn't give you anaerobic effect in a running activity if you do not reach Z5.



For example, I did a recent 8x hill sprint workout (1 minute fast, 2 minutes recovery) and got high aerobic primary benefit. The HR chart shows clear HR peaks and valleys. My HR was getting down to around 110 each recovery, but the peaks were 167, 170, 171, 171, 172, 172, 172, 173. I think Garmin gave me high aerobic primary benefit because half of my intervals did not reach Z5.

It's confusing because it's much easier to obtain anaerobic benefit on non-running activities. For example, I got anaerobic benefit for one hour of recreation volleyball. For that activity, my average HR was 122, my highest HR was 162, and most of my HR peaks were under 150 (<78% MHR). 

I'm thinking of changing my HR zones so that Z5 starts a little lower, maybe 88% MHR . It's frustrating when I do a difficult anaerobic workout and Garmin doesn't reflect that.

  • 0 2 days ago

    The goal of anaerobic benefit is "sprint" or "interval" performance. It is not based solely on hitting zone 5, which is where high aerobic comes into play.

    An example workout that should get anaerobic benefit almost every time is a 30sec-1min run at a really fast pace (with the HR getting into zone 4/5) and then recover until the HR is all the way back down into zone 2.

    That "spread" (going from zone 4/5 into zone 2, then back and forth) is going to improve your sprinting capacity and your body's ability to accelerate effort over a short time.

    I recommend visiting this page, which has additional info on Training Effect and anaerobic training effect: www.garmin.com/.../

  • 0 2 days ago in reply to Garmin - DK

    Thank you for your response. In my experience, this does not seem to be the case for running activities. It is very easy for me to get anaerobic benefit for short bursts of intense effort on other activity types, but for running specifically, I only received anaerobic when I reach Z5. I’ve been doing the same anaerobic hill sprint workout for more than a year (about one minute max effort up a hill and walk down recovery). I get down to Z2 during the recoveries, but there are times I can only get my heart rate up to the very top of Z4 (often only a beat or two under Z5) and when this happens during the workout,I always get “high aerobic” benefit. 

  • 0 2 days ago
    9745928 said:
    I believe that Garmin doesn't give you anaerobic effect in a running activity if you do not reach Z5.

    I don't think so. Recently I did a short warmup with 2 x 20s and 4 x 30s of strides (equal time rest). recorded as a separate running activity from my main workout (which was LT pace intervals).

    The strides activity received a 2.1 anaerobic training effect ("Maintaining Anaerobic Power") and the primary benefit label was "Anaerobic". My HR never went higher than zone 3.

    To be fair it wasn't "high" anaerobic benefit (e.g. 3.0-5.0), but there was still anaerobic benefit, and the primary benefit label was anaerobic as opposed to aerobic.

  • 0 2 days ago in reply to flowstate

    That’s interesting. Can you share the chart showing pace with heart rate zones?

    here are four of my recent ones all doing about a minute of all out effort followed by walking recovery. Whenever my HR didn’t peak in Z5, I was given more aerobic benefit than anaerobic benefit. Even the one where my HR peaked only 1-2 beats below Z5. 

    the first two photos counted as anaerobic and the last two did not. The fourth one especially was frustrating not to receive anaerobic benefit. 

  • 0 2 days ago in reply to 9745928

    Sure. I usually use min/km, but I am guessing from your charts that you use min/mi, so I changed my Connect unit settings to statute/miles before screenshotting the charts.

    I'm not sure, but I think the reason I only got a mild anaerobic benefit (2.1) is probably because I never made it to zone 5 (or even 4). I also didn't run very fast, but I think that's secondary. (After all, I've gotten tempo aerobic benefits for runs I felt were very slow, when I was in even worse shape. I'm not 100% sure how the watch would determine what a  proper tempo or anaerobic pace would be, unless it compared your speed to your VO2 Max, race predictions, or LT pace. I'm not saying it's impossible, just that I'm not sure to what extent - or exactly how - the watch would take your speed into account.)

    I do think the reason I got a mild aerobic benefit at all (i.e. greater or equal to 2.0) is because I ran very short intervals. 

    Max HR: 194

    LT HR: 172 (I don't think it matters tho *)

    LT Pace: 7:19/mi (4:33/km) (also don't think it matters *)

    (* One reason I don't think it matters is that in the past, you needed to do a guided LT test with chest strap to get LT values. But even if you had never done this, the watch would still have to be able to calculate training effect.)

    Primary Benefit = Anaerobic Capacity

    Aerobic = 1.4 (Recovery)

    Anaerobic = 2.1 (Maintaining Anaerobic Power)

    EDIT: I love how the scale on both of our charts makes it tough to determine exactly how fast we ran haha, since we kept periods of rest (moving slowly or not at all) in the activity, which causes most of the y-axis to become useless due to Connect's choice of the y scale (and also serves to flatten out the variations at the top / important part of the scale). Both the Connect app and the website have this problem.

    So to make it clear, I averaged 5:41/mi (3:32/km) on the work intervals / strides.