Heart rate 25-30 bpm higher after flu recovery

Hey Everyone,

I got a bad flu (not COVID-19) and had to take three-to-four weeks mostly off from cycling, running, etc. While easing back into workouts I noticed that my average heart rate for workouts is about 25-30 bpm higher than for the same workout pre-flu (e.g., 128 vs 155 for Pettit).

For reference, I did get blood work and other tests done since it aligned with an annual physical, and nothing appeared unusual. Additionally, I cross-checked the heart rate data from my Polar strap against my Garmin watch and both pretty closely mirror one another so it isn’t a device issue.

Lastly, although I’ve noticed slightly elevated heart rates after being sick or taking time off in the past, it’s never been to this extent and on a prolonged basis. It also doesn’t feel like I’m working as hard as the heart rate suggests. Has anyone else experienced something like this before?

Thank you!

Yes, after 3-4 weeks off my fitness declines by a lot. My on ramp to training is doing 1-2 weeks of easy aerobic workouts by HR, to get the cardio engine warmed up. Then start training again.

Some people don’t lose fitness as fast, and bounce back quicker.

Pretty normal. You have lost fitness and probably a lot of blood volume build during training so you heart has to beat more often to pump the blood.

Thanks for the feedback. It seemed like a greater deviation than usual for fitness loss, but perhaps I’m just getting old…:unamused:.

Thanks for the feedback. It seemed like more of a fitness loss than usual, but it’s a longer than usual break. I’ll keep at the low intensity endurance work a monitor performance.

Just looked because I was riding by HR for 3-4 weeks…. In September my second week of restarting cycling (not training), riding at zone2 HR had power at 120W for an hour. A month later it was back to 180W. Pretty big jump. I remember being happy when it went above 150W at same HR.

Scrolling back to Christmas 2017/2018 when I got a bad flu that almost killed me (a year and a bit later I found out why :open_mouth: ). In Dec 2017 my Ave HR for cycling was around 125bpm and post the flu in Jan 2018 it was circa 145-150 bpm for cycling. A fluctuation of that much is definitely not normal for me however but you’ve had blood works and other tests done so I worry about anything untoward and I hope you are back to normal shortly.

Thanks for sharing your experience with building back up. I’ll keep going with the lower intensity endurance rides and cross training for the next 3-4 weeks and see how heart rate trends.

Thanks for sharing your experience and I’m glad your recovery went well. It seems like, unfortunately, I’ll have to suck it up and build back over the next 3-4 weeks before jumping into more intense training.

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Same happened to me recently after a surgery. The preceeding weeks were:

  • 1 week off after an A race
  • 4 weeks of Z2 only
  • Surgery then 2 weeks off

Resting heart rate jumped 25bpm along with a similar increase for Z2 rides. Dropped FTP from 240 to 200 to get the HR about the same for long Z2 & Z3 rides. 2 weeks into structured training again and things are now starting to point in the right direction and I expect to regain the old fitness pretty quickly (say 2-3 months). Resting HR is still 60 (was 42) so that has a long way to go.

I appreciate your sharing your recovery timeline. It sounds pretty similar with my resting heart rate coming back a little faster (back down to 55, but still have a little way to go). Hope you get back to full fitness soon!

@Mjthomas85 Did this ever normalize? I also had the flu or another virus (not C19) a few weeks ago and have just been doing endurance rides - but my heart rate is 10-20 beats higher for the effort compared to pre-illness. My resting is only about 5 beats higher.

My plan is to stick to Z2 until it normalizes.

How long did it take for your HR to get back to normal after the illness?

@jreinfeld My heart rate did normalize. Working off memory (timeline might not be precise) I got back into training with zone 2 work at the low end and progressive intensity still within zone 2 for about 6 weeks. Once my heart rate for endurance rides was back to a pre-sickness level, I started a low volume TT training plan where I added easy zone 2 work rides twice a week to bring training up to 5 days per week for cycling. Over the initial 6 weeks, my resting heart rate returned more or less to normal and during the TT training block (9-12 weeks) resting heart rate was slightly elevated after hard interval days and returned to normal after recovery days. As for today, my resting heart rate varies based on intensity. During a recovery week, it’s around 50-55. During a training week, it’ll be around 52-55 going into a hard day, 55-58 after a hard day, then back to the 52-55 range before repeating the process. One difference between now and prior to getting sick, I had some more flexibility for higher training volume around 10-15 hours per week when you include running and strength training. Today, I am around 9-11 hours with a mix of 6-7 from cycling, 2-3 from strength training, and the remainder from running. If I increased volume and reduced intensity slightly, then I think the physiological factors would align to bring about a lower average resting heart rate, but it’s not a direct apples-to-apples comparison on training since I am doing 20-30% less volume with a little more intensity which skews the recovery cycle. Overall, I did recover and get back to normal training loads, all else held equal. Hope this helps. Let me know if you have any follow-up questions and I’ll try to answer them as best as possible.

Edit: I forgot to mention that during the initial 6 weeks of progressive zone 2 work that I probably got back to “normal” sooner, but locked in on a six week timeline before starting a training plan. My thought was, “alright, time for some aerobic base building for six weeks as I fully recover” so the timeline towards normalcy might be faster.


Thanks for this- I really appreciate it

Just waiting for my HR to normalize - I feel OK otherwise

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If it reassures, I’ve had exactly this.

Pre-illness (mid November): rhr ~46, approximate VT1 (via the talk test) ~140bpm/195w.

2 weeks post illness: rhr ~62, approx power at 140bpm = 160w.

This week it has normalised (i.e. returned to what it was about 8 weeks ago). Like you, after week 2, I didn’t notice a higher RPE.

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I’m glad you’re feeling good overall. I think the biggest thing is to just keep it easy and give it time. From what others have said, 3-6 weeks, depending on the person, from severe respiratory-type illnesses seems to be the rough timeline. Let us know when you get both RPE, RHR, and workout HR back to normal.

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That’s this week (what I rather vaguely described as ‘normalised’). It’s taken about 8 weeks.

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Took me a month from coming down with C19.

Two weeks completely off the bike. Week 3 was endurance only. Week 4 started adding in some intensity but kept it light because heart rate was still elevated even though I was feeling better. Week 5 back to normal…

Good point, I forgot to note that my timeline was from when I started training again. I took about 4 weeks off from cycling, running, etc. before starting the 6 week aerobic base training.

You keep it z2 until it normalized? Or just back into intervals?