RHR declining and increasing strongly?

[misscopilot]

Hey guys!

My resting heart rate went from 76 to about 61 in around 2 weeks. While I already found this strange, I did start cycling around 4 hours a day or more for my job, so I thought maybe it could be. However, now it went from 61 to 68 in 2 days. How can this be? I havent really changed anything and I even drink more water. Don't feel like I'm getting sick or anything either. The only thing I have since 2 days is moderate muscle pain.

Is this normal? It just seems so unrealistic, in both directions.

Thank you for your answers!

[Heybales]

It's actually not unrealistic.

A little bit of improvement fitness could be part of it.

Did you start a diet too?

That will lower it.

The Fitbit reading of restingHR is not what anything else would consider RHR - which would normally be wake up in morning and take pulse before moving.

Did you start using the Fitbit recently to just start noticing these changes?

Because Fitbit will change that RMR figure (it's not a measurement since they are taking all day averages along with night-time and running it through calculations).

Due to that it is awfully hard to make assessments of anything due to variances over a few days.

If interested in what the real RHR can tell you as far as overtraining, getting sick maybe and body fighting off something, getting more fit, ect - start taking and noting your own true RHR figure in the morning.

If alarm freaked you out on wakeup, lay there and calm back down for a few min.

Just rest and note what the Fitbit says your HR is.

Do that every morning or few mornings. Or if you trust it, look at daily 24 hr graph right before wakeup and note those numbers and compare.

Now you have a meaningful number.

What has been reported to you as RHR could easily be each day the same actual RHR, but Fitbit is tweaking it from other things that occur during the day where it is including some data.

[sspeed]

I would just watch it over time and not worry about it.  Eventually with enough data you'll have a reasonable, consistent number.  Personally I think a change from 76 to 61 in two weeks is unrealistic and probably more of measuring variance than an actual fitness change.  How long have you been watching it?

[Baltoscott]

RHR will be affected in unpredictable ways if you don't wear your fitbit 24/7.  In particular, Fitbit suggests you wear it to bed.

[emili]

and... you could be suffering from allergies or your room could be colder and your HR is up consistently to keep you warmer... it could be anything. If you don't feel unwell, keep your eye on it but don't stress.. now that will cause your RHR to go way up 🙂