High heart rate while doing Sweet Spot

Hi, all, I’m doing the low volume base plan (24F 124 lbs) and seem to be averaging a very high heart rate for sweet spot. I just did Carson -3 yesterday and averaged 175 bpm and max 188 bpm – it wasn’t even that hard of a workout for me. I’m not overweight or anything and have an average resting heart rate around 48 bpm. Is this extremely abnormal or even unsafe?

What’s your max heart rate?

It seems pretty high of a heart rate to me, with your resting heart rate being low. Especially with you saying it wasn’t that hard. How difficult was it? How are your threshold or VO2 Max workouts? What is your max heart rate?

Have you checked to ensure your HRM is working correctly?

192 is the highest I’ve seen it on an outdoor ride and 197 during one ramp test last year.

I mean it has full batteries and is the wahoo tickr so I feel like it’s correct.

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I mean it was challenging since it was my first ride in a whole week (since I got too busy) but not an all out effort and didn’t feel like threshold. I could have put in another 8 intervals probably after the hour was done.

For threshold and VO2 Max it’s usually max hr 188 and average is around 160-165 since there are so many rest intervals.

As long as you can recover from this, its probably totally fine. For me, long threshold efforts take a lot out of me, and I need some good recovery. I can recover from everything else totally fine, but long threshold can require a few days to recover.

It looks to me like you are very close to your threshold here. But if it doesn’t feel that difficult and you are recovering, then you are in your “sweet spot” of challenging work that you can quickly recover from.

I say all this as a fellow athlete, I am not a coach.


thanks – I think this is good feedback. I guess maybe I got worse (my max 20 min power was 170w last Sept. but then I got busy with work + not enough sleep) and my ftp is lower than I thought. Muscularly I don’t feel the burn like I do with over/unders or other threshold work, but yeah definitely takes some mental strength to get through these sweet spot intervals. With low volume I think I have enough time to recover, but good point that I might actually be at a higher % of true ftp than I actually think.

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I think that is probably spot on. If they are a challenge to finish, then you are probably very close or even over threshold.

Way to finish though!

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I use heart rate as a secondary metric. It is much harder to quantify what “good” and “bad” numbers are, because that changes over the season as you get fitter and depends on a whole bunch of external factors (temperature, humidity, fatigue, sleep, etc.).

Heart rate should not automatically override RPE, i. e. if something feels easy and your heart rate is higher than what you’d expect, it is still easy. E. g. if my heart rate recovery during a rest interval is good (according to my experience), I know I am fit enough to continue the workout even though I might not feel great that day. Conversely, if my heart rate is higher than expected, but I feel great, there is nothing for me to do other than keep monitoring the situation. Only if both indicators point in the “bad” direction do I pay attention to how I feel and perhaps pull the plug.

Looking at the workout @anon98 has posted, it looks reasonable to me: I see no indication of fault heart rate data (usually plateaux). His heart rate recoveed in the rest intervals, and as the workout went on, the lowest heart rate during the rest intervals increases steadily. That indicates to me that the difficulty was spot on.


You mention your Max HR is 197 or thereabouts.
188 then is relatively high, but considering this was done indoors it could be down to insufficient cooling.

My HR for efforts indoors are always significantly higher then equivalent efforts outside.


Ya the heart rate sounds higher than you would expect for sweat spot. Dehydration and heat can elevate you heart rate.

Another possible explanation is bike choice/position. If you test in one position and train on another bike or position you can see these issues because your FTP can vary depending on the bike/position. For example, there aren’t many people who have a TT position that is within 95% of their road position. There is a metabolic cost to mashing yourself up into an aerodynamic position.

If the high HR was just a fluke, your HR should be more inline with what you would expect during your next interval session If your FTP is too high, AI ftp detection will reduce your ftp or a ramp test will give you a lower value. It never hurts to schedule a ramp test and see what AI ftp detection gives you.

Something doesn’t seem right, but without looking at your data it is hard to say and you are just getting a lot of guesses. I could toss in a couple of guesses but again, without looking at your data they are just guesses.

What doesn’t seem right? What data would be valuable to have?

AI ftp wanted to even increase it 5 watts and I declined

Are you keeping your room temperature and cooling conditions consistent during these intervals? I’ve noticed massive differences in Heart Rate for prescribed intervals if humidity and room temp are higher or lower. I started tracking those variables with a Govee Thermometer to be as scientific as possible about it. Pretty cheap relative to all the other bike and training stuff out there. $10, battery last forever, simple to use app, with Bluetooth connectivity.

Ive my max set to 197bpm as a 46 yo FWIW and in a threshold TT I’ll exceed that without doing damage. My mate of the same age will exceed that again in every ride. So unless you’ve got a history of heart problems and its sustainable (SS should feel hard but sustainable) I wouldn’t worry. It is a bit high though for me for an indoors SS session.

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Something seems off:

  • maybe the room temperature was high, or you didn’t have good cooling
  • maybe your HRmax is actually higher than what you think it is
  • maybe your FTP is set too high
  • or maybe its not off, because your FTP is really high % of vo2max, and your threshold HR is close to your HRmax

How confident are you of HRmax on a bike? Have you done a race ending in 6-8 minutes over threshold and then sprinted?

How confident are you of FTP? Do you have some solid 20 or 30 or longer efforts where you were going full gas and your brain was screaming to stop at the end?

Do you have any good estimates of HR at threshold (LTHR)?

Just a few off the cuff thoughts.