Greetings.

I'm 63 years old and parallel to the topic I am about to expand upon, am trying to self-diagnose what are still mysteries in my overall health in the past two years. On our favorite two-wheel instrument, my strength dropped suddenly last year in May by about 10% - and never recovered. Without a better theory, I chalked that up to an aging burst. However, throughout, my average heart rate was always in the mid to upper 140s, and my maximum around 166 or so....until.

Suddenly, about a month ago, I lost ten beats, both on my average and the maximum. I assure you this is not over-training (my regimen year-to-year is almost robotic) and also not a burst in fitness (or I'd not have maintained the power and speed loss).

Can anyone think of any medical reason for this heart rate loss? Thanks

Who knows with so little info. See a Dr. Self-diagnosis over a period of time is beyond foolhardy!

Riding route changed or modified?
Develop an arrythmia? Bundle branch block?
Time of day change for your rides?
Temperature changes?
Stress? BP changes?
Resting heart rate change?
Did you suddenly get an aero position?
Illnesses? Inflamation?
Other activities?

Equipment wears out. Double check with new gear.

edit:
My guess is = you went tubeless and the lower rolling resistance is immediately obvious in effort required.

Any new meds? Many have the side effect of lowering BP, possibly heartrate, and some can also inhibit epinephrine/adrenaline, so you're not getting your normal boost of that during exercise.

Both consult your doctor, and wikipedia, as I've found that sometimes doctors can leave out mentioning a critical side-effect. I do both, and never start a new drug without researching it myself. In one case long in the past before I did my own research, I suffered a severe side effect which I later found out is common and the doctor never mentioned it. In a more recent case, the doctor recommended a med on their last visit with me, they were leaving, I researched first, and there were huge red flags such as highly addictive, never use as first course treatment, and if needed, use only for limited time. I mentioned this to the new doctor and they were like, "Uh... that was bad advice."

65 years old and retired. Lost 3 pounds and the heart rate dropped 10. Was always in the mid 60's since in my 20's, now in the mid 50's. My friend who is a silver olympic medalist in the 68 games remarked to me a few months ago that she can no longer get her heart rate up past 120. She is 73 and has been focused on athletic performance since age 13.
I think it is likely you are aging just fine.

I am not a doctor, but... you should probably ask a doctor about it instead of randos on the internet.

I just seemed to do the same thing recently. I'm 67. Between last year and this year I seem to be down 10 bpm on my max. Partly I put it down to some extended times I was not able to ride last year that normally I would have been riding. And I never got back up to my peak performance last year either.

I'm not worried about it. It just is what it is. If at your age you aren't seeing a cardiologist somewhat regularly, then I'd suggest you do.

Maybe need new battery on your heart rate monitor?

I had the same thing happen to me about 2 years ago, I'm now 73. I went to a heart specialist and a pulmonologist, and they all concluded 2 things, first my heart, arteries, and lungs are 100% clear, and they both said my stuff was that of a mid 30s person. So, I asked what the problem was, they think, after looking at my medical records, the situation I was experiencing was due to long term covid. But that leaves me scratching my beard, was it the covid, or was it the two Moderna shots I got? They won't tell me if it was the Moderna shots, just that it was from covid, they will never admit it was from the shots.

I ran into a person about this same subject, he had the same symptoms as I have, he's about my age, he never got Covid because he got the shots, hmmm.

I can't say what you're going through is that, but that's what happened to me for seemly the same experience.

But like others here have said, go to a SPECIALIST in heart and pulmonary.

Just to be on the other side of that experience, I had COVID and Moderna vaccine. I didn't have any HR bpm issue within the years after that once I fully recovered.

Your issue might be like what I suspect about mine. Just too long a period of inactivity. It'll be a few months before I can ask my cardiologist about it though at my annual check.

I have never worried about my maximum heart rate, focusing instead on my resting rate (low 50s, was in the low 40s when I was in top shape in my 20s) and above all on my recovery rate. I push to about 120, then see if I am back to 72 or lower within a couple of minutes.

Another see a doctor, hopefully a cardiologist, though even that's iffy. Most cardiologists have no experience with aging aerobic athletes, thus trying to get a diagnosis is iffy. Been there, tried that. Took 2 years of things getting worse to figure anything out. But you never know, you might happen upon an exception. Nothing gained by not trying.

For sleuthing this sort of HR problem, I rely on taking my morning resting and standing-resting HRs. In your case, probably too late, you would have had to have been doing that long enough to establish a baseline and have seen how it varied with training inputs. What happens in overtraining is that exercising HR w/r to effort drops and morning resting HR increases. I'd see a rise of say 4 beats in MRHR and would back it off for a day or two, see what happened to my MRHR. A rise of 6 beats would mean back it way off for at least a week or until it came back down. I don't know if you have any data for that, but it's worth a look or a check.

Plus n (where n is a large number) on the cardiologist. I got an echocardiogram this spring which showed, totally asymptomatic, aortic stenosis. Untreated, it will damage the heart muscle and lead to a permanent slowing of the heart, to zero. Corrective surgery, a new valve, is scheduled for mid September. Without the scan, I could have gone along until I did irreversible damage. So go see the Doc.
On a more general topic, my good level of fitness makes me a better surgical candidate, so keep riding everybody.

I have had covid (once) and about 5 mRNA COVID shots. Have not had the experience of sudden reduction of maximum or average HR. The hypothesis that an mRNA shot could have this effect strikes me as a wild extrapolation from very little data.

However, I do see seeming fluctuations in my average and maximum HR, and I have for at least 15 years. It is partly related to fitness and partly a mystery. I tend to think that my body has a low heart rate mode and a high heart rate mode. In the former, my average HR is lower for the same exertion or average power, and also I have trouble achieving my maximum HR, which has changed relative little since I started keeping track in my late 40s (I'm 64 now). In my high HR mode, my average HR is higher, and I can get my HR up to at or near my max (which is 181 BPM now, and was 184 15 years ago). In the low mode, I won't see much above 170, no matter how hard the effort, and mostly I stay below 168. Over periods of months, I go from one to another and back. The LHR mode tends to correspond to higher training volume, but not exactly.

I would talk to your Dr and ask why is my resting heart rate 140 (if I exercise regularly).
It seems a little high despite your age. Also discuss any medication side effects with your Cardiologist while you're there.

They didn't say that 140 bpm was their resting heart rate. That would be alarming. Said it was their average HR for their rides.

Thanks for the clarification.

any changes in diet? caffeine, of course, has as significant impact on heart rate, ditto alcohol and a few other things. cold meds, immune response, etc. my heart rate jumps 10% a few days before i get the symptoms of a cold and also increases around that much from morning to afternoon as the catecholamines build up. stress and other adrenaline reactions do even more so. if i look at rides over a long period of time, the largest variation is what time of day the ride was. any chance you've started riding earlier? your 10 beats is only around 7 percent, well within the range that all those variations could produce.

anything more pathological than that .... certainly hard for us internet randoms to diagnose, and probably for a doctor as well without before and after testing of various types. the before will be hard to get at this point

the single greatest driver of the power : heart rate ratio for me over time has been left ventricular volume, which is seen and calculated with echocardiograms. if you had one done before and after, it would be interesting to know if there's a difference. ejection fraction will also factor in but it seems unlikely that your EF spontaneously went up unless you're recovering from disease or taking some serious meds.

Assisted self-diagnosis is usually better with some feedback.
17 replies over 10 days, 0 response.
Oh well. Good luck. Don't lose more beats.

I was kinda interested in the subject, before.