Ok. I know none of you are doctors and I'm not asking for medical advice (unless you ARE a doc and then feel free).
Most definitely not a doctor, so take what I say with that caveat.
I'm looking over my heart rate data from the last year or so.
At this time last year I was running about the same distances with similar paces.
But my heart rate last year was 20 beats less/min last year when compared with this year.
So, obviously I've had some significant changes in my life since then and I'm wondering if I should go see a doc or maybe get a second heart rate monitor for running.
Before my accident I had a different fitbit and all of my heart rate data shows less with that fitbit. My resting heart rate was 46/47 with the old fitbit. And with the new fitbit it's never been less than 51.
Is it possible the new fitbit is reading wrong/differently?
Or is it possible that I have an diagnosed issue from the accident?
Or am I just in worse shape than I was at this time last year?
Or am I just being paranoid and need to relax about it? Maybe I'm just putting too much stock into the numbers.
I'm definitely not pushing myself any harder than I was last year. As a matter of fact I'm barely winded after the runs. That's one reason I'm so confused, I still feel like I have tons of gas left in the tank, even after my long run.
I feel if I go any slower to keep my heart rate down, I might as well be walking...... ugh
There are certainly confounding factors with the comparison of your HR data now to a year ago. The accident and changing devices are two variables.
1) Are you on any medication that you weren't on prior to the accident (and you don't have to answer this on here, but more so think to yourself). Because medications can definitely alter HR output (both during life and during exercise).
2) Second is that without testing the two devices side by side, it's hard to say which is real and which was not. Although 20 bpm is way beyond what I would consider a marginal error difference between the two devices. The resting HR is close, but how about the maxHR? On what you would consider hard runs, have you seen similar top end values? Because if the maxHR for one device has dramatically shifted, then so would the %HRR relative to that device. Thus, 65% HRR would be two different HRs which in theory could be separated by 20 bpm (but again seeing that big of difference in two optical HR monitors would be surprising unless one of them was truly junky). So while we can't conclude it isn't the devices differences, as long as they were both properly worn, I'd venture to guess this is not the case.
So for the sake of argument, let's say the two devices should output the same value, and that you aren't on any medication or had any ill effects from the accident. Is it possible for your HR to be different at similar distances and similar paces to last year? Certainly. A few other considerations when trying to do a HRvPace comparison.
1) Temperature + Dew Point. The T+D of a run can easily influence the relationship between HRvPace. As it gets hotter, we have to work harder to maintain the same pace. Working harder to maintain the same pace means we're likely to output a higher HR average. You said compared to a similar time last year. So it would stand to reason that you may be experiencing similar weather.
2) Elevation gain. The amount of hills in a run can easily influence the relationship between HRvPace as well. Do a super flat run and you're likely to see your best HRvPace relationship. Do a run with a ton of steep hills and yet maintain the same pace as the flat run, then you're likely to see a worse relationship between HRvPace. Because the HR will be reflective of the extra effort necessary to maintain pace on the hills. So are the course maps of the runs today similar to those from last year?
3) Loss/Gain of fitness. This is at the core of why we would even do a HRvPace comparison. It's a secondary mean (primary being PacevEffort and race performance) by which we can assess performance increases or decreases. If we isolate the other key variables (same device, T+D is similar, and elevation is similar) then we can start to make comparisons of today's HR data (as an average) compared to past performances. Something like this:
Where over the course of several two week chunks, the relationship between HRvPace can be flushed out and graphically represented with a logarithmic curve of best fit. The trend downwards of the sets of lines, shows increasing fitness. As one becomes fitter, they can maintain a faster pace at the same relative HR. All of this data is from Spring 2017. As you've read, I've gone through a period where I hadn't run in 19 weeks. My HRvPace data since my return (based on a small 10 run sample set), suggests my relationship is most similar to the 2/4/17-2/17/17 line (Black). My HR on my most recent run was 140 for a 8:31 min/mile average. I've changed locations for my runs, but the elevation gain on average is similar (about 30-40 feet per mile gain). So after 19 weeks off, my fitness has fallen quite a bit. For comparison, when I was at my peak in July 2018 right before my ankle injury, my HRvPace data would have probably been around the last orange line. An 8:31 min/mile now at 140 was a 127 then (or a 13 bpm difference). So it's reflective of the fitness loss between then and now.
With that being said, there is one reason my above example falls apart compared to your current experience. The effort at which it takes me to currently run an 8:31 min/mile is not the same effort that it took me to run an 8:31 min/mile back then. It's harder for me. And I know I've lost fitness since then. I've done a few effort tests in my few runs and can agree with my current assessed fitness based on the HR data. So where my effort is not equal, you claim the effort is equal but the HR is off by 20 bpm. And that's where I'd go back to the original. It would seem to be a possible medication or variance in device. That's by no means a conclusive answer, but an initial assessment of the situation.
At the end of the day, I wouldn't necessarily worry about it. I use effort as my gold standard for training. But not everyone has a honed in gauge on their own effort. So my back-up is using pace from a recent race to set up goal pace zones for types of runs. With the understanding that those pace zones can be altered by T+D and elevation. So if you reasonably believe that you could run a similar mile PR or 5k PR as to last year, then I would continue to train at similar paces if it feels like a similar effort. This is because I view HR data as a secondary measure. But if you're uneasy about it (as your original post would indicate), then I absolutely won't discourage you from talking with your doctor about it because they're the expert on medicine/physiology. I'm more of a science/data type person.