anemia's effect on HR?
I am hoping someone has some insight into this. I started the OS in November and a couple of weeks in, was diagnosed with anemia (again, unfortunately). I have now had a month or more on iron supplements. What I have noticed is that my HR for any given effort has come down. Last season, when I probably got into the anemic range, I noticed that my HR, on the run especially, was higher than I was used to given previous seasons (probably 10+ beats per minute at any given level of effort) and now it is back to where I remember it.
Was the high HR due to the anemia? Or is the lower HR now just due to how awesomely fit I am becoming on the OS plan? 
And, should I do anything with my zones? Or just stick to the pace/watt numbers I am working with, ignoring the HR data?
Thanks in advance for any help!
---Ann.
Comments
RBCs carry oxygen on hemoglobin (built with iron). Fewer RBCs means less oxygen carrying capacity. This can result in higher HR at the same level of effort.
Iron deficiency anemia (IDA) can cause fatigue and limit endurance. Correct the IDA and fatigue and endurance should improve.
Depending on how low your iron stores are (were) can factor into how long your recovery takes.
Now you are becoming more awesomely fit. So the HR, for the same level of effort, should come down a bit anyway, all other factors being equal.
Best way to determine zones is to test, not guess. If you are a pace/ power athlete, HR is a nice extra metric and good for spotting illness (as in this case), but should not determine your pace/ watts.
As you get healthier, your pace/ power should get better.
Hope that helps.
Back prior to my senior year in college I was diagnosed with Crohns and had an immediate small bowel resection. During that summer I rehabbed and got into REALLY fantastic shape. Started the school year 20lbs lighter than I'd ever been. I had always been a bit chubby. I felt healthy and strong (go figure) and my swimming shape was outta this world for me.
Previous years I'd routinely sit around a 5:15 500SCY swim and then taper into the 4:50ish range.
That year however was different. Early in the season when I was normally around a 5:20 I swam 5:01's in back to back meets after really tough weeks of practice. I was thinking I might qualify for nationals...something I hadn't really thought of prior to that. But between the weight loss and being in better shape...I was fast. Across the board I was faster in everything even the 200 which I hated.
Out of the blue I started getting tired in practice. The workouts and meets were really really hard and I didn't know why. My times went from 5:01 to 5:30 over the course of several weeks. In the water my muscles burned like never before. I was panting and couldn't get enough air. I have no doubt my HR was through the roof.
Came to learn that the crohns led to a little bit of internal bleeding and I was literally low on blood = anemic.
Went in for a transfusion and got better very rapidly after that. (along with meds to stop the bleed).
You'll have to figure this out as best you can based on what you know for you. But I'd say yes...the hr being high is a result of the anemia. Your body was trying to get blood and oxygen to the areas that needed it...and you didn't have the blood to do it with.
I am also somewhat anemic....just a couple of points below what's considered the norm, so not ridiculously so...but statistically relevantly anemic. They looked at me for Crohn's, Celiac, and 800 other things (including getting a bone marrow biopsy...they were apparently pretty worried!). I took iron under medical supervision for several months over two different stints in different years, and the bottom line is that there was no explanation ever found for my anemia, and the iron didn't change anything. I also did the B12 thing...also no help. Bottom line was finally that I was just declared to be the guy on the far side of the bell curve. So my experience is someoen with modest but constant anemia, not someone who is getting better...
There is little doubt that the HR will go down at the same pace if you either get fitter or if your anemia improves. If you mean "perceived effort" rather than pace, the relationship with HR can be more complicated, though. You could be going faster at the same PE, for example. Not clear how your HR should respond to that...
It's very easy to believe that you're just getting fit It would also be nice to think your anemia was getting fixed too, but you won't know that until you get tested again.
In the meantime, I totally agree...use the zones that you test to, and stick to pace running if you can....especially if you don't really trust your HR to be meaningful for you. If you've improved and you have several weeks until your next test, you can always re-test now and then again 4 weeks from now (or whatever is on your schedule). If you are going to test in the next week or two, just hang on and do it then!
Hi Ann,
I ended up on iron infusions in 2008. Changed my life. It was sobering to sit there with all the chemo folks, that's for sure. I did it for 6 weeks.
My PCP wanted to take no action, thought I was nutz, and my numbers were "low normal." My very enlightened GYN, said, "get thee to a hematologist." The hematologist said, "you sure do need to be here."
As it turned out, I also had RLS (rest leg syndrome), which, if you can believe it, can be due to anemia. My insurance paid for the infusions based on the RLS to cure it. Go figure. The iron did take care of the RLS problem too.
Long way of saying, supplments never did squat for me. I don't absorb enough. I had to go down quite a road to get the infusions, but it was worth every minute of time and effort.
I feel your pain. My story is meant as food for thought for you.
Thanks, all! Your comments and insights are very helpful. Even at the best of times I sit in the "low normal" range and I do get better on the supplements - but they sure are nasty! I am continuing to just pay attention to the watts and pace prescribed by the last testing I did. It will be interesting to see what happens at the next test in a couple of weeks. But my guess is that I can no longer get my HR up into those ranges where it was a couple of months ago.
Interesting comment about sleep disturbances though. I am sleeping better the last month or so. I did not have RLS but would just wake repeatedly during the night. Now I am not - so maybe it is the iron levels coming up that explains that too.
Thanks everyone!
---Ann.