Cobbler and why a low heart rate?

Been with Systm for about 3-months and every workout has been as expected, generally rather tough. Today Cobbler was strange. Ran it as programed but heart rate never got above Zone 2. From reading the description I expected to struggle maintaining a high Zone 4 heart rate. Looking for opinions as to why the workout ended up being easier than expected. I have two ideas:

  1. Today was just a super day for me. (unlikely)
  2. My body just does crazy good with lower cadence drills. (more likely)

Any thoughts?

could also be a sign of over training


I never get target heart rate. I also take blood pressure meds. Also make sure your heart rate strap is tight or put water on the sensor.


Low cadence drills put the stress on your muscle and not your CV system. I barely break out of Zone 2 on Power Station and G.O.A.T. I don’t remember what I did on Cobbler though. Thus, you could be just fine or maybe heading towards overwork. I use HRV to determine how I’m doing. I had to bail on a 100km ride that I love due to an abnormally high HRV today for instance. Two days of riding into very stiff breezes did not help any.


I was in mid-upper Z3 for pretty much all of Cobbler today. For me, the lower cadence definitely keeps my heart rate down a bit.


Was it actually easy or do you just mean that your HR was lower than expected?

I did Cobbler this evening and my HR was quite low but there was a large pool of Holy Water under the bike when I was done and now my legs hurt. Easy it was not.

Thanks for the ideas. On the effort scale Cobbler was about a 6 or 7 out of 10 which is surprising because my weak area is long sustained efforts. So far, this workout is an outlier and we’ll see what happens as I gain more experience. Again, thanks everyone.

I have a similar experience with largely zone 2 heart rate on Cobbler. On my last cobbler attempt, I was 62% Zone 2 heart rate and 30% Zone 3 heart rate, while Power was 50% Threshold zone 4 and 18% Tempo Zone 3. For me, my heart rate stays low with sub-threshold rides with cadence < 95.

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My heart rate is almost always lower than expected. But on yesterday’s cobbler I rode between 125-100% to get (according to the training description) 2-5% below LTHR

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I think there are a couple of things going on here. We’ve checked the targets and while there are definitely some legit periods of Z4 riding, some of the heart rate zones were set too high for the power and cadence targets. Those have been fixed, but even still, nobody should be in zone 2 on this workout. If that’s the case, we’d recommend retesting to get more accurate training zones. If it’s been a while since you’ve done a 4DP test, I’d put that on your to do list!


Thanks for the added reply and further checking. There are just so many variables at play. My 4DP profile is new but have only been riding for a year and three months on the trainer, maybe (hopefully) my improvement curve is still quite steep. Stay safe.

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