Heart rate response blunting

Apologies for the long post, but this has been driving me mad.

I have been having issues with intermittent blunting of heart rate response for a few years.

First off, I’m a 47yo guy. Max HR is about 196. Resting is about 50. Lactate threshold is about 175bpm. FTP is around 305w. I ride about 8 hours a week, a mixture of indoor, outdoor road, and MTB. I’ve been riding at a similar level since my teens. I suffer from postural hypotension with syncope. Full cardiology investigation last year revealed nothing major.

A typical outdoor ride might be 3 hours, 160bpm average, 188 max, 250NP and 210 average power. Indoor, I tend to reach higher max HR, often low 190s with maybe an average power of 260w for an hour. I don’t sleep much, c6hrs a night, but that’s been the case for a long time.

Occasionally, I have a ride where my HR will not go above about 165bpm. I will be breathing hard, and the watts are there, maybe a sustained climb at say 350w for several minutes. the HR goes into low 160s and then just won’t budge. Lactic acid builds in the legs and I have to back off. I’m just unable to hold the power for any length of time. I might try a shorter effort of say 450-500w and the same happens. I can finish a 3 hour ride with an average of 140bpm, max of say 168 and literally 0% of the ride in zone 4, in spite of hitting steep hills as hard as I can, or trying to ride at FTP for longer periods. This even happened at reasonable altitude, around 3000m . These rides are just horrible. I can often tell in the first half hour whether it’s one of those days and I frequently bail.

(By “occasionally”, it could be anything from once a fortnight to every ride for two weeks, then ok for a couple of weeks etc. It’s not every ride (or i’d just conclude my max HR was much lower) but neither is it like once a month.)

The frustration is being unable to predict when it’s going to happen. Sometimes it will happen after a heavy week, so i think maybe it’s fatigue. Another time, it’ll happen after several days, or a full week off, so maybe not. Sometimes i might have had alcohol the night before or a bad night’s sleep, but then other times that hasn’t been the case. It seems to happen equally in the afternoon and evening as in the morning. I haven’t been able to connect it to diet or fluid or caffeine intake. It seems to happen just as much when relaxed and having fun (MTB) as indoors after a difficult day at work.

From what I’ve read, all these negative factors ought to cause an increased HR relative to power and RPE. I’m getting the reverse. For say an 8/10 effort, maybe 280w for 10 minutes, my HR stays way too low, doesn’t feed the muscles, and I have to curtail the effort.

This has often happened on the day of races and other important rides.

Can anyone suggest reasons why, on occasion, my HR just won’t respond to the demands from my muscles? What might i be overlooking?

Thanks in advance.

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When your heart rate isn’t increasing like it should and your max heart rate is suddenly lower, that’s a sign of being overly fatigued / stressed. Keep in mind that this does not just mean bike stress, but all stressors. And it doesn’t necessarily mean you physically feel tired. It means your mind and body stress combined are too high.

If you have HRV data, you can use that as another check, (you want HRV to be high, if it’s low, you’re fatigued). But based on what you said I think there’s already plenty of you’re over fatigued.


Are you tracking HRV? That’s where I would start, the only times I’ve had something similar it was because my body was very poorly recovered. With the lack of sleep your talking about 6 hours or less a night I would assume your HRV is generally pretty low which can lead to compounding issues when it comes to overtraining and ability to recover.

My guess is that you are just worn out on those days where you cant raise your HR (on the edge of overtraining) and your max HR is correct. Are you a) getting enough recovery in and b) training to close to those important events. Sounds to me (not that I’m an expert) that you need to increase your recovery/ rest days both throughout the season and on the build up to events.

FWIW your HR stats aren’t far off mine at 47yo (197bpm max 50bpm average resting) but we are all different there.


Thanks for the replies.

I am not tracking HRV. Devices available to me are my Edge 530 and a Fenix 5 watch. The Fenix has a crude “stress level” but I doubt that’s sufficient for this purpose. Is there any way of measuring this without a new £600 watch?

I have considered whether overall life stress might be a factor, and it might. I’m quite anxious i guess, and i have a fairly stressful job. However, I tend to suffer quite badly when riding in the morning on a family summer holiday. Riding on my own, Tuscan sunshine, quiet roads, 30 miles to a cafe and then back to the pool. Ought to be as low stress a ride as they ever come.

When you’re over stressed to the point that is suppressing your heart rate enough that it’s obvious, it’s much more stress than you can recover from in a week. It’s not only your conscious stress, it’s what your subconscious and nervous system feel. People sometimes need months of recovery when they burn out. And If you just stop riding, but still have a bunch of life stress, even that might not be enough.

I’m not saying that you’re quite there yet, but your likely getting pretty close. If I were you, I would take a week off from riding and focus big time on reducing life stress, eating well and sleeping well. Then just do super light Z1 exercise for a few weeks, monitoring my HRV to tell me when I’m getting better. There’s apps you can get for your phone that accurately measure HRV with your camera and light. The best is HRV4Training. It’s cheap!

I used to only sleep 6 hours a night and feel fine. But that’s because I had a high stress job and had consistently high levels of cortisol (stress hormone). When I got a less stressful job I suddenly naturally slept longer. There’s such a thing as sleep training that can help too.

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I think the Fenix 6 was the first that tracks overnight HRV and sleep score, you can find the Fenix 6 for about $300-$350 USD on Ebay and could probably sell your Fenix 5 for $150 or so, might be an option to upgrade. I had the Fenix 3 before and upgraded to the Fenix 7 and I think it was worth it just for the HRV, body battery, and sleep tools alone.

Oh just in case @Gingerflash1975 (and I’m sure its not case as you are only experiencing this occasionally) I guess I better say this. In 2018 I was suffering with the inability to raise my HR and had to similarly back off but it was all the time for me. Everyone was telling me I was overtraining and I needed to rest. When that didn’t work I was getting told I was so overtrained it take months to recover. But it turned out to be a bowel (colon) cancer blocking iron getting into my system. On hindsight a simple blood test when it started would have identified any abnormality earlier. Once the cancer was whipped out in April 19 almost overnight my HR was back to normal.

"But it turned out to be a bowel (colon) cancer "
Wow. My dad died of bowel cancer, and i do have bowel issues, but my symptoms have been static for like 10 years so i doubt that’s a problem. Cardiology investigations last year, for postural hypotension and syncope, said i am not anaemic.

Some reading this afternoon suggests a link between low HRV and postural hypotension, so maybe my autonomic nervous system is just in really poor shape, inhibiting HR response and also blood pressure response to standing up.

I think perhaps I’m just generally not taking enough care of myself, particularly on the sleep side. I say i’ve slept the same for years but actually i don’t think that’s true. My son started a new school last sept which meant we all get up over an hour earlier. I have not yet managed to go to bed any earlier.

Poor sleep might also explain why this affects me most when on holiday (strange bed, maybe alcohol too), when at altitude (I sleep terribly in the mountains), and at major events (nerves).

Lots to think about there. Thank you all.

I’d also think it’s likely due to stress/fatigue, but…

Have you checked it’s a true reading with a second device? Maybe your HRM just has issues sometimes.

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I doubt it is too but given you have family history (sorry for you loss btw) for peace of mind I’d get blood tests. I think when I was suffering the occasional sore stomach in 2016 like the night before the 312 (I thought it was just heat stroke/ nerves) on hindsight it could have been the start of it. A blood test probably would have been normal then; a year + later would have been very different. I had no history of it in my family that I knew of until my 80yo mother got it the year after me. Fortunately because there was a history in the family now (me) they got it fast and in its early stages its pretty routine.