Accuracy of Heart Rate Monitors

lessertess

I'm hoping one of you personal trainers or researchers can answer this one....

I thought that you measured metobolic rate by determining your body’s exchange of oxygen and carbon dioxide while at rest. If that is the case then how does a heart rate monitor give you an accurate reading of calories burned by measuring how fast your heart is beating? In the long run, isn't it just another estimate? And if that's the case, how accurate is it?

I've always wondered about this because, as you become more fit, your heart becomes more fit and has to pump less to move blood through your body. So, logic would assume that you burn less calories as you become more fit. But, presumedly as you gain muscle mass, your metabolism increases. How does this all balance out?

I could be completely misunderstanding how heart rate monitors work but I recently read up on the "bodybug" and it just struck me as an estimate similar to what we do on MFP.

lessertess

I'm hoping one of you personal trainers or researchers can answer this one....

I thought that you measured metobolic rate by determining your body’s exchange of oxygen and carbon dioxide while at rest. If that is the case then how does a heart rate monitor give you an accurate reading of calories burned by measuring how fast your heart is beating? In the long run, isn't it just another estimate? And if that's the case, how accurate is it?

I've always wondered about this because, as you become more fit, your heart becomes more fit and has to pump less to move blood through your body. So, logic would assume that you burn less calories as you become more fit. But, presumedly as you gain muscle mass, your metabolism increases. How does this all balance out?

I could be completely misunderstanding how heart rate monitors work but I recently read up on the "bodybug" and it just struck me as an estimate similar to what we do on MFP.

lyla29

I had a similar question because I was burning more calories according to my HRM when I first started some new fat burning dvds, but after I got better at them and built more muscle, it said I wasn't burning as many calories. I thought, just as you did, that when you gain muscle that you increase your metabolism.

songbyrdsweet

Well, that's the problem with a HR monitor, and they even state it in the instructions; there's a large margin of error.

What you're thinking of are METs, or metabolic equivalents, which measures the ratio of exertion in comparison to your baseline metabolic rate. Lying down = 1 MET. Walking = 2 METs, Jogging = 3METs, etc. (those are just estimates, it's different for everyone). METs are based on oxygen consumption, which is indeed how we measure energy use. If we measure our energy output using METs, it's more accurate. Interestingly, cardio machines use METs, but they estimate our METs based on weight/height/age and assume they're constant for every person of our size, which makes them very inaccurate.

As you become more conditioned, you have to work harder to elevate your HR. Whereas some people may be able to walk and reach 65% MHR, some may have to jog or run. You can burn the same amount of calories in that period of time, you just have to work a lot harder because you become more efficient.

HR monitors, however, don't measure metabolism, which includes alllllllll bodily processes. HR monitors estimate energy output for a given period of time at a certain heart rate.

A Body Bug, as you probably read, measures a TON of stuff...I think even temperature and movement are taken into account. Heat is a good indicator of metabolism...our metabolic reactions create heat as a by-product (which is why our metabolisms will increase if we are REALLY cold for a long time...just to warm us up).

So, unfortunately, that's your answer...HR monitors are only good for estimating the calories we purposefully 'waste' with exercise in a short period of time at a certain HR, not of our overall energy production.

Carrie6o6

Would you consider a HRM to be more accurate than the gym machines and what this website says? Or about the same?

shorerider

Would you consider a HRM to be more accurate than the gym machines and what this website says? Or about the same?

HRMs are much more accurate--the machines are set to be based upon an "average" person and this website, as any website, cannot take into account your heart rate during exercise--therefore, any guess on your part as to exertion level is just that, a guess, and can be way off.

songbyrdsweet

Would you consider a HRM to be more accurate than the gym machines and what this website says? Or about the same?

Hmmmmm....sort of depends on the HRM. The upper-end ones that measure your 'Own Index', which is an estimate of your VO2Max, would probably be more accurate. If they estimate METs as well as averaging calories burnt/heart beat, it'd be even better. I have had a tough time finding just what formula they use to estimate it. Subtracting your BMR calories makes either measurement more accurate too.

firegirlred

I would trust the accuracy of a heart rate monitor before a general "average," even on MFP. Heart rate is an excellent indicator of "current fitness." For example:

If you are dehydrated, your heart rate goes up,
If you are getting sick, your heart rate goes up
If you have had a ton of caffeine, your heart rate goes up.

All these things are associated with increased metabolism and a greater calorie burn. As one person noted on here, a hot environment can even cause your heart rate to go up for the same workout previously conducted in an air conditioned environment.

Unfortunately, most averages don't take this into effect. Use the item designed to take the most factors into accounting. Usually this is the heart rate monitor.

My resting heart rate is 52 as of last night. Four months ago, it was 72. Yes, your metabolism goes up with the greater amount of muscle, but you also burn calories more efficiently. It's a give and take game. I've plateaued for nearly a month, but I've lost fat. So I've gained muscle. So higher metabolism, but a lower heart rate. I hear Lance Armstrong's resting heart rate is about 40...

songbyrdsweet

Haha I always feel bad for Lance...because you know his *warmup* has to be as intense as some of our *workouts* to get that HR up! Same goes for veteran triathletes and the Marathon Man lol

firegirlred

I was pretty cranky yesterday about my workout. Finally got properly hydrated and I couldn't get my heart rate over 135 for a challenging cardio workout. I actually checked to see if my heart rate monitor was working...

songbyrdsweet

I was pretty cranky yesterday about my workout. Finally got properly hydrated and I couldn't get my heart rate over 135 for a challenging cardio workout. I actually checked to see if my heart rate monitor was working...

Yep, before the summer I was up to running an hour a day 6x a week for a few months...on days I was a bit more tired it SUCKED because walking did absolutely nothing for me! And I always feel like the first several minutes of cardio are a waste because it takes forever to get my HR up unless I start right out on the stairstepper. Congrats on the RHR drop! Mine is still somewhat high at 60, but my BP has dropped from 120/80 my freshmen year to 90-100/60-70 four years later.

firegirlred

*sarcastically* Somewhat high at 60.....

You crack me up. But the blood pressure thing rocks. I'd love to do the same thing.

songbyrdsweet

*sarcastically* Somewhat high at 60.....

You crack me up. But the blood pressure thing rocks. I'd love to do the same thing.

LOL well high compared to you and Lance!

arjames82

I'm hoping one of you personal trainers or researchers can answer this one....

I thought that you measured metobolic rate by determining your body’s exchange of oxygen and carbon dioxide while at rest. If that is the case then how does a heart rate monitor give you an accurate reading of calories burned by measuring how fast your heart is beating? In the long run, isn't it just another estimate? And if that's the case, how accurate is it?

I believe that that measure you are referring to is the VO2 rate. My personal trainer measures mine periodically, and that is input into my HRM, in addition to my height, weight, age etc.

lessertess

Thanks songbyrd. I was hoping you'd have the answer to this one. Appreciate the help :happy:

songbyrdsweet

I'm hoping one of you personal trainers or researchers can answer this one....

I thought that you measured metobolic rate by determining your body’s exchange of oxygen and carbon dioxide while at rest. If that is the case then how does a heart rate monitor give you an accurate reading of calories burned by measuring how fast your heart is beating? In the long run, isn't it just another estimate? And if that's the case, how accurate is it?

I believe that that measure you are referring to is the VO2 rate. My personal trainer measures mine periodically, and that is input into my HRM, in addition to my height, weight, age etc.

I was reading in another thread about all the measurements you get...that is awesome!! It's great to hear about a PT doing something worthwhile instead of telling you to live off whey shakes or avoid anything heavier than 3lbs. You're lucky to get such a holistic training experience.

songbyrdsweet

Thanks songbyrd. I was hoping you'd have the answer to this one. Appreciate the help :happy:

No problem Something similar actually came up in another thread a few days ago, it dealt with METs too. There's an equation out there for them, but don't ask me to remember it lol, I am badddddd at math :ohwell:

firegirlred

My heart rate monitor does V02. Polar f55.