Heart rate high 30,s, low 40’s

[SABurg]

Hey, was just looking for some thoughts from people. 

So as far as my Fitbit records go (2017) my average heart rate has been in the 40’s. Last week my RHR has been from 42-45. Often, at night it drops to 35, and as I wake and laze around it hangs there. I was concerned previously (2020) and got everything checked out by my doctors and even an ECG at A&E and they weren’t concerned (said they only get concerned if regularly below 35), but it still plays on my mind. 
I’m 33, run around 3/4 times a week from 5-10K, eat decent enough, feel fine in myself, but just almost a little scared sometimes to keep training in case my HR goes any lower!? What’s everyone’s thoughts?

Cheers!

[JennyTheUnfit]

tldr: I reckon don't take advice from strangers on the internet, trust your doctors.

I'd go with what your doctors said - they're the experts. It sounds like they took it seriously, had a good look at it, and didn't see a problem. 

That said, I've been looking into low heart rates a bit as mine occasionally drops (while I'm awake) for an hour or so from my normal RHR of 61 down to ~45 (when I'm asleep it doesn't go below 55). I was a bit alarmed but as far as I could tell it's not worth worrying about unless you're also getting dizzy/faint or other symptoms alongside it. Constant low heart rate it seems can be a sign of bad things, but the ones I know about would have shown up on your ECG and so would have been ruled out. 

I'd not worry about it unless it regularly goes under 35 (ie as your doctors advised), and/or if you have dizzy/confused spells (a sign of low blood oxygen), or are feeling breathless. I have a pulse oximeter, which showed that even at 43 bpm my blood oxygen was totally normal, which was reassuring (I know this is higher bpm than yours, but it shows that a drop below RHR isn't necessarily a problem).

I know a few people who do lots of cardio and have RHR of 50 so you're not that far into the weird zone (I think everyone goes a bit below RHR when asleep?).

[t.parker · Accepted solution]

@SABurg if clinical tests show that everything is fine then I'm not sure what do you expect to hear here 🙂 Everyone's individual story is different. You seem to be quite fit, too. I can tell you that not everyone's heart behaves according to medical books and it doesn't mean there's something wrong with it. At night, especially when you sleep your HR will drop a lot because your body has not much to do. That's why sleeping HR (which often is a minimum HR) and resting HR are not the same.

I can give you my 7-day RHR from last week:

I'm 40 and fit. As you can see I'm not that far from what you're describing. It's not night HR but actual resting HR (my sleep/night HR may fall even to 30-32bpm). On the other hand, my max HR is 189bpm so I have quite a high heart-rate reserve. What does it mean? Nothing particular. Numbers are rather meaningless. More important is whether your heart responds correctly to certain actions. For example, if your HR was very low and despite exercising, it doesn't go much up (so you get dizziness, out of breath, not enough oxygen circulating despite effort) - that's bad. If HR doesn't drop when you expect it (so-called Recovery HR) - another reason to worry. Look at patterns, not numbers and listen to your doctors and to your body. Don't go crazy about numbers. If you feel great, you run, you're fit and your RHR is low - congratulations! You're probably in the top 5% of all humans with your level of fitness.

[SABurg]

I think my issue is I’m a worrier 😅, but your reply (and Jenny’s) are great reading, and I really appreciate it. 

For example, if your HR was very low and despite exercising, it doesn't go much up (so you get dizziness, out of breath, not enough oxygen circulating despite effort) - that's bad. 

That's why sleeping HR (which often is a minimum HR) and resting HR are not the same. Thank you for this as well; I was not aware of this information! 

Really appreciate the replies! 👍

[charleskn]

@t.parker is right on. I'm in a similar situation. 60 years, 200+ pounds, fit, but not overly so (my 5k time are in the low 30s), and my RHR used to be low 40's but has recently (yeah) crept up to the high 40s. Additionally, it's normal for your RHR to drop further during sleep as part of your body's recovery process.

In my case, while I am fit, I am not (IMO) 40+ BPM fit. A year ago I started experiencing occasional AFib during HIIT workouts. The cardiologist said everything is fine. While there are possible causes (such as low thyroid), here is the real question: After getting good test results (stress tests & echo-cardiograms), do we experience any symptoms that would indicate issues with heart rate, blood pressure, etc. as @t.parker mentioned? If you don't get dizzy standing up after bending over, or going up stairs, etc. your heart is responding appropriately to the change in load, and you're probably fine. 

That said: listen to your body, and talk to your doctor.

[strngemily]

That is a common resting heart rate for an athlete. Don't sweat it. 😉

[FitbitUser416]

 I would see advice from your doctor only.