Covid vaccine affecting fitness + causing long-term rise in HR?

For the last month or so, my heart rate has been consistently higher for the same intensity factor as it was until early April (and anyone in Britain can confirm there’s been not much increase in temperature!). I did Townsend (90 mins .63 IF) at 107bpm in March and 117bpm last week. I did a ride to Windsor at .69 IF back then and only averaged 107bpm, whereas at the weekend I did the same route at .63 IF and averaged 112.

I’ve also noticed that HR seems to be less aligned to RPE than it used to be. Today on a long Z2 ride I felt pretty comfortable but it kept going up to levels I’d associate with tempo.

(I also think my resting heart rate is higher but I don’t have any really reliable or regular measurements from before to make a firm comparison with.)

Any thoughts on possible causes? I’ve tried to google it but most of what I’m seeing is regarding either a dramatic rise in heart rate, or for people who do little exercise at all. I’m now double-jabbed, and if I did ever have Covid, it was the most symptomless bout of it anyone’s ever had. I had put it down to fatigue, but am still seeing the same results even after a good stint of rest and recovery.

Edit: Have changed the title of thread as the discussion below has me 99% convinced the vaccine is the cause of the issues.

for me personally, my heart rate is higher when I am sick or getting sick. But since that doesn’t seem to be the case for you, is it possible you have just lost some fitness?


Any noticeable changes to sleep, caffeine, hydration, nutrition, time of workouts, etc, etc? Indoor vs outdoor? Is power measurement the same?


I have lost some fitness (which is another reason I’m thinking there might be an underlying health cause), but I’m comparing HR vs IF, not HR vs Power - I’m correcting for that change in fitness already.

1 Like

No… for example, if anything I’ve become MORE diligent about sleep and nutrition since I started noticing this, just to make sure I was definitely fully recovered. Same power meter etc, indoor workouts in a cool room with a powerful fan each time, etc. Definitely been trying to eliminate those variables.

I suppose if I was to summarise the question more simply, it would be - are there any underlying medical issues that might slightly but measurably reduce your fitness and slightly but measurably increase your heart rate, while still being able to work, train, and live your life pretty much as before?

(I’m thinking of asking a medical professional to do some sort of blood tests, but I have really no idea what I might be asking them to look for.)

1 Like

when was your second shot? My resting heart rate was up about 10 beats for a full month after my second. I didn’t really notice my heart rate higher during exercise, but don’t discount the vaccine as the cause. About a month after everything went back to normal.


Actually it was last week! Although the raised HR issue started well before that. The full sequence was…

March 6: Test FTP at 275
March 11: First jab (no noticeable side effects)
March 12 - April 6: continue training and then tapering with no obvious increase in HR
April 7: failed FTP test
April 8 - May 15: continue alternately training / recovering with noticeably raised HR
May 16: Test FTP at 265
May 20: Second jab (again no noticeable side effects)

So I’m definitely not ruling out the first jab as the cause - and it’s really interesting that you had a similar small but sustained increased in HR. But it seems a bit odd it didn’t happen immediately after that first shot.

I may have had a reaction to the first, but it was just too small to notice.

A blood test would probably be a good place to start. It could be any huge host of things from spring allergies, dehydration, low salt, low iron, underactive thyroid, etc etc. So all of that stuff could be easily found out or ruled out with a blood test.

It could even just be a bit more stress from work, personal, COVID, etc.

1 Like

When did you last have a recovery week. Is it your body saying it’s accumulated a lot of training stress and now needs to absorb it?

@PhilW When fatigued HR is generally lower.

@martinheadon higher cadence can raise HR. Any noticeable difference there?

I was referring to stress rather than fatigue, not the same thing.

My TrainingPeaks form was +15 when I did my last FTP test after a recovery week. Did another very easy week and form reached +37 before resuming training on Sunday and again today, with same results.

No, plugging away at 85-95 as normal.

Fatigue, stress TSS whatever. Drive it into the weeds my man.

Hey you don’t understand. I get it.

My HR is always higher when I am fresh or I have drop in volume. Looking at my Z2 rides my HR differs around 5-7 bpm for the same effort for no particular reason. What is interesting doing something like 0.6 IF can easily elicit exact the same HR as 0.75 IF. I stopped to care about this some time ago as RPE is in line.

I second this, my HR can very quite a bit with Z2 rides and I don’t pay it much mind.

Are you seeing similar increases at higher intensities?

What @russell.r.sage said…my resting HR was jacked up for a good month after my second shot. Trained fine, hit all my numbers and felt very strong, but resting HR (and Readiness Score from my Oura ring) were all off.

Resolved itself in time…

1 Like

For me personally it has been either I am getting sick or am sick, my stomach is too full, the temperature is too high, the intensity/pace has been too high or I’ve lost fitness. Temperature is a big one for me.