Can anybody help solve this HRM conundrum?

cmw72

I've purchased three Polar FT60's in the last few weeks. One for myself, my wife, and my mother. All three of us selected "Weight Loss" as our primary goal when we created our training programs. Consequently, we were each assigned similar training plans. We're all supposed to do about 40% in Zone 1, 60% in Zone 2, and 0% in Zone 3.

My mother's stats: Age 62, 5' 1", 134.0 lb, OwnIndex: 25
My wife's stats: Age 34, 5' 3", 138.2 lb, OwnIndex: 33
My stats: Age 36, 5' 9", 289.0 lb, OwnIndex: 36

I'm extremely happy with my FT60 and the Star training program seems spot on for me. My zones just feel right.

Here's the problem ...

My wife and my mother both do Zumba 3-4 times a week. During Zumba class my wife is usually in Zone 3 (or beyond) with an average heart rate around 160. Meanwhile my mother is working just as hard and is barely able to get out of Zone 1 (if at all), with a heart rate around 109. I'm no expert, but 109-110 seems low to me, given her level of exertion.

I watched my mother on the treadmill the other night, power walking at 3.8 mph, with an incline of 4%, and swinging 2lb dumbbells, and her heart rate stayed firm at 109. Tonight she did an hour on the elliptical, and was in Zone 1 the entire time, despite trying as hard as she could to increase her heart rate. Both times she was completely exhausted by the end.

She swears she's wetting the strap adequately, and that the strap is snug, and that she has the transmitter centered and in the correct position. I know the HRM unit itself is not faulty because the machines in the gym are picking up her signal from the transmitter and displaying the same exact heart rate. She takes medication for high blood pressure, though I don't know if that could cause an abnormally low heart rate.

My wife probably needs to take it a little easier. She's not really happy with that solution, but she can probably deal with it. But my mother just doesn't have any more in her to give. She's working out to the point of exhaustion as it is. I see no recourse but to alter their zones manually at this point.

Jax67

I don't have an answer but feel this should be bumped up to see if anyone else can help. :huh:

sonjavon

What is your moms resting heart rate? Is it possible that it's low to begin with and the HRM is not recognizing that 109 for her is in the higher zone? My mom is about your moms age and has a very low heart rate - she laughs and says that her's is that of an athlete... and it is, but my mom is no athlete.

Maybe your mom should reset her "Own Zone"?

I really don't know the answer - but I'm just trying to throw out some possibilities. The other thing she might want to do is ask her doctor to do a stress test for her - that way he can help her find a "target heart rate" that's right for her.

xecila

Is blood pressure meds the only thing she's on? I know in the case of my mother, she takes a multitude of medicines (diabetes, blood pressure, things like that) and they've subsuquently lowered her average heart rate. The blood pressure medicine your mother is on may have done the same thing.

firegirlred

IF your mother is on a beta blocker for her blood pressure, this is likely your culprit. Beta blockers act by blocking the beta receptors in the heart and lungs (more specifically the heart). By slowing the heart rate, the medicine lowers minute volume (how much blood is pumped in a minute). This allows for lower blood pressures, but creates low heart rates, and prevents the heart's normal response to exercise. You can find out if the bp medicine is a beta blocker by some internet research.

Talk to her doctor. If she is in a position to come off the medicine, you'll find her heart rate gradually respond better to the exercise over the next two weeks.

firegirlred

And about your wife. There is nothing wrong with being in the "wrong zone." Eventually she'll train her heart to respond better to exercise and she'll find it harder to get her heart rate as high as she does now. Enjoy it while it lasts, it will be MUCH harder to get as good of a calorie burn later. And she"ll enjoy the benefits of a healthy heart.

cmw72

Hey, thanks for all the replies.

I talked to my mother about her medication. She's taking metoprolol, which is indeed a beta blocker.

From what I can tell, that pretty much throws the results from the FT60 out the window. The heart rate would be accurate, but the fitness test results and the calorie expenditure could be way off. :frown:

I did find an interesting thread on the Polar forums that talked specifically about that medication:
http://forum.polar.fi/showthread.php?s=b43604557bfac0576c858d62ae8bd45f&p=20036

Azdak

Hey, thanks for all the replies.

I talked to my mother about her medication. She's taking metoprolol, which is indeed a beta blocker.

From what I can tell, that pretty much throws the results from the FT60 out the window. The heart rate would be accurate, but the fitness test results and the calorie expenditure could be way off. :frown:

I did find an interesting thread on the Polar forums that talked specifically about that medication:
http://forum.polar.fi/showthread.php?s=b43604557bfac0576c858d62ae8bd45f&p=20036

Holy crap--no wonder she is exhausted.

The first time I ever saw an exercise bike with a heart rate sensor (no Polars then) was in 1984. I think it was called a biodyne. Several guys in their 30s were trying it out. Two of them got on and revved it all out, seeing how high they could raise their heart rates. I was distracted by another member with a question, but when I looked up again, the third one was going all out. He was bald and his head looked like a giant tomato ready to burst. I ran over and politely asked him WTF he was doing. He pointed at the display and said he was trying to get his HR up like his buddies. It was about 102 (the others had reached 170s). Sure enough, he was one the original old-style beta (a lot more powerful than the ones used today).

Well, you have just conducted a self-clinic on the vagaries of human HR response and the limitations of HRMs.

There is a lot of variability in the human population when it comes to maximum heart rate (HRmax). All HRMs use a variation of the 220-age formula to calculate HRmax and Polars based their programs on that number as well. Those formulae all have a SEE of 10-12 bpm, which means that fully 1/3 of the population will have a true HRmax 10-36 beats above or below (if I remember my statistics) the age predicted HRmax. In my experience, the percentage is even higher among females. Plus, people who exercise regularly throughout their lives often do not see the same age-related HRmax drop that sedentary people do.

To get the most out of your HRMs, you must enter in the most accurate setup data possible. If you let the HRM do all the thinkin' then both HR recommendations and calorie counts can be way off.

It would seem that you fall within the "calculated" range, hence your zone numbers work for you. Your wife's HRmax is obviously significantly higher that what the HRM is predicting and your MILs HR is attenuated by her medication.

What to do? Max exercise testing is an option, but hardly practical (nor recommended in this case). The next thing is to compare the HR response you observe with perceptions of perceived exertion. You can look up "rate of perceived exertion" and get more detailed info about the number scales. Get a sense of what constitutes "easy", "medium" and "hard". From that you can extrapolate an estimated HRmax. Program that into the HRM and I think --in your wife's case at least--it should recalculate the zones. Match those again to perceived exertion and adjust up or down as necessary.

You can try the same thing with your MIL, but I don't know if the percentages increments will still hold true. You will also need to check and see if the HR response changes according to time of day. Sometimes when you are taking a beta blocker 1x per day, the blood levels aren't as consistent.

cmw72

Hey, thanks so much for that informative reply.

That's some good advice, and clearly I have a lot more research to do!

cmw72

A bit of an update ...

I made some manual corrections to the personal data in my mother's FT60.

Her max heart rate was set to 159. I lowered that to like 130. I also manually bumped up her V02max by a couple points because I figured it was also artificially low. This gave her much more realistic zone targets. I don't know how accurate they are, but they are at least reasonable.

The only issue now is the calorie burn numbers. Both my wife and my mother did Zumba last night. According to their FT60's my wife burned about 500 calories, while my mother (doing about the same workout) only managed to burn around 225. Her heart rate really is lower, but she is doing the same amount of work. So does that mean the calorie burn really is accurate? Or is it being under-reported?

At that rate, she will never be able to hit her STAR training target for calories expended, unless there is a way to manually edit those target numbers. Perhaps I should recreate her training program and hope that the FT60 will give her more realistic goals now.

I'm also curious to see what will happen next time she runs the Fitness Test, and if I'll have to manually edit those numbers again.

Hopefully when she see's the doctor again in a few months, her overall fitness will have improved and she can get off the high blood pressure meds. At least for now, her FT60 is working for her and she's happy with it.