On a med to control HR, so how to calculate zones?

givprayz

I know this is not a medical advice service, and I hold no one responsible for their input, but I'm curious if anyone else has experience with exercising while on a medication to control heart rate. My doctor gave me his blessing on exercising and losing weight, but I didn't think to ask about the whole heart rate issue, and we all know how hard it can be to get any answers from our doctors unless we are in the office talking face-to-face, which I won't be for another 6 months.
I have tachycardia (high resting heart rate) which is well controlled on a beta-blocker. The problem is it is almost too well controlled. I can't get my heart rate into the "cardio" or "fat-burning" zones without about killing myself. Now I know I am in poor physical shape, but I have been walking 3 miles 5-6 days-a-week at a 4 mph speed for at least 4 weeks now (after building up to that over about 4 weeks time) yet even when I put on an interval burst, I can't get above about 130 bpm. I'm not explaining this well, but the point is, regardless of my exertion level, changing up or ramping up what I am doing, my heart rate remains pretty stable in the 110's to 120's. Has anyone else had a similar problem and found a way to get around it?

TrainingWithTonya

The backbone of my exercise physiology program is cardiac rehab, so I understand exactly what you are talking about. I could even tell you how the beta blocker is working on a cellular level to slow your heart rate, but I won't bore you with that. For our patients on beta blockers, we don't use heart rate at all for determining workout levels. We use a rate of perceived exertion scale. Some people use a 6 to 20 scale but our program prefers a 1 to 10 scale because most people can relate to it better. With one being laying on your couch doing nothing and 10 being the maximal exercise you can do, you want to work out at what you would estimate is a 5 or 6.

Has your doctor ordered a stress test? If so, the exercise physiologist who performed it may be able to prescribe an exercise program for you based on the results. That may only be available if you are enrolled in cardiac rehab though, just depends on the hospital/program.

givprayz

I am 45 and have been on the med for about 5 years, since a cardiac cath/ablation procedure failed to find the source of the aberrant heart rate. I believe the problem was caused by an ephedra-containing OTC I used to lose weight about 8 years ago. I'm an RN, so I understand my problem pretty well, but where I have issues is utilizing the fitness materials that rely heavily on heart-rate to judge exertion levels. Even calorie burn calculations always use heart rate. It seems there should be some way to quantify these things for people like me. :frown:
I have never been in cardiac rehab, nor had a stress test. I have low cholesterol and great BP (even before the beta-blocker), so it is just the idiopathic tachycardia. Otherwise I have a very healthy heart.

Azdak

I am 45 and have been on the med for about 5 years, since a cardiac cath/ablation procedure failed to find the source of the aberrant heart rate. I believe the problem was caused by an ephedra-containing OTC I used to lose weight about 8 years ago. I'm an RN, so I understand my problem pretty well, but where I have issues is utilizing the fitness materials that rely heavily on heart-rate to judge exertion levels. Even calorie burn calculations always use heart rate. It seems there should be some way to quantify these things for people like me. :frown:
I have never been in cardiac rehab, nor had a stress test. I have low cholesterol and great BP (even before the beta-blocker), so it is just the idiopathic tachycardia. Otherwise I have a very healthy heart.

Any calorie calculation that is based on heart rate is bogus to begin with, so don't worry about those. The aerobic energy cost of an activity is the same, regardless of heart rate, and that's what determines caloric burn. Beta blockers pose other challenges for losing weight and losing fat, so your results will likely be slower--although from your ticker, that doesn't seem to be a problem.

That being said, the previous advice about using perceived exertion is the best idea. Perceived exertion, once you get the hang of it and learn to be aware of your breathing, can be very accurate--sometimes more accurate than heart rate. Look up information on the Borg Perceived Exertion scale. I personally prefer the original 6 to 20 point scale--I think the descriptive cues make more sense than the 10 pt scale--but that could just be because I learned RPE using the 20 pt scale so that is the "language" I am most comfortable with.

You could try a symptom-limited graded exercise test, but I doubt that you would get much useful information. It is my experience, especially these days, that most institutions do a mediocre job of administering exercise tests. Almost none of the techs or doctors understand how to do them, nor do they understand how to administer them to get any useful information concerning your aerobic fitness level. They let (or sometimes require) you hold on to the handrails and they almost never push you to anything close to a maximal effort. Plus, depending on the medication, your HR response can vary at different times of day, depending on the levels of the med in your system.

Most of the exercise guidelines will still be the same for you--you just won't be able to rely as much on heart rate, that's all. If you need to estimate calories, I would just multiply your body weight in kilograms by 5 to get calories per hour and divide that by 60 to get calories per minute. That will sometimes be an underestimation, but that's ok--you really don't have to be that close and you should only be eating a modest fraction of your exercise calories anyway.

It's important to keep in mind that heart rate is ONLY important as an indicator of a percentage of your maximum. For example, heart rate "x" might indicate that you are working at 70% of your maximum--your maximum HR or maximum VO2. It doesn't really make any difference what the actual number is. For a 20 year old, a 70% effort might result in a heart rate of 180, for a 70 year old, it might be 120. Both individuals would be working at the same relative intensity.

The same thing holds true for someone on a beta blocker. The beta blocker lowers your maximum heart rate--that just means you are on a different scale. A 70% effort is still a 70% effort, even if now it only elicits a heart rate of, say, 120 instead of the 140 you might see in a 45 year old not taking a beta blocker.

TrainingWithTonya

I am 45 and have been on the med for about 5 years, since a cardiac cath/ablation procedure failed to find the source of the aberrant heart rate. I believe the problem was caused by an ephedra-containing OTC I used to lose weight about 8 years ago. I'm an RN, so I understand my problem pretty well, but where I have issues is utilizing the fitness materials that rely heavily on heart-rate to judge exertion levels. Even calorie burn calculations always use heart rate. It seems there should be some way to quantify these things for people like me. :frown:
I have never been in cardiac rehab, nor had a stress test. I have low cholesterol and great BP (even before the beta-blocker), so it is just the idiopathic tachycardia. Otherwise I have a very healthy heart.

Okay, I'm not a cardiologist, but Dr. Carter, the professor who teaches all our cardiac related classes, seems to think we're all going to be one day, so this makes sense to me. Sounds like an overactive electrical conduction system to me. Beta blockers are definitely the way to go for treatment. Wow, I have so many things running through my head right now of tests and treatments. Thanks so much for helping me study for my Cardio Phys final. :laugh: It actually makes it easier learn when you can relate to actual people instead of trying to learn it from a book.

As for calorie burns, use the METs system. Basically, a MET is a multiple of your normal metabolism. So, the standard is that normal metabolism is a burn of 1 calorie per kilogram of body weight per hour, which is 1 MET. Then as your intensity increases, your MET level increases. Several types of exercise have been studied to determine their average MET level. Granted, you can work harder or easier then the people who were studied doing the same exercise, but it's an average so it is close even if it isn't perfect. To determine how many calories you've burned, just multiply the MET level by your weight in kilograms to get calories per hour. Here is a great METs compendium that lists the MET levels of a lot of different activities. http://prevention.sph.sc.edu/tools/docs/documents_compendium.pdf

givprayz

Thanks both of you for the info, and glad I could help with the studying. I have hit a new interesting situation since I just ramped up to a new level. Now when I try to push past an exertion level, I get dizzy. I am thinking that my body/brain need more oxygen, but my heart refuses to increase flow. I am forced to back off until my breathing slows, then I can start increasing again, but I will get dizzy again if I work too hard. I have been taking my med first thing in the morning, as I always have, and then exercising. I am going to switch my med to after exercise and see if that improves it. I get so frustrated, especially when I think I probably did this to myself by using that suppliment. It worked well at controlling my appetite, but it was so-o-o not worth the long-term effects. I am a huge opponent now of all diet aids and energy boosters for that reason.

girlsaint

I am interested in this as well, but I also have a question. Does Tachycardia increase the amount of calories you burn at rest?
Also, in my cardiac rehab program, I was limited to a heart rate of 100, based on a stress test. My HRM was then set to alarm at that point. Problem is, now my RPE is much lower when doing more (probably a result of getting healthier. I want to go go go, but that granola-crunchin'-recumbent bike-ridin' cardiologist of mine seems to be sitting on my shoulder telling me not to overdo it?
Will I EVER be able to be sure of myself, raising my heart rate to 130-150? I want to participate in Zumba

Azdak

I am interested in this as well, but I also have a question. Does Tachycardia increase the amount of calories you burn at rest?
Also, in my cardiac rehab program, I was limited to a heart rate of 100, based on a stress test. My HRM was then set to alarm at that point. Problem is, now my RPE is much lower when doing more (probably a result of getting healthier. I want to go go go, but that granola-crunchin'-recumbent bike-ridin' cardiologist of mine seems to be sitting on my shoulder telling me not to overdo it?
Will I EVER be able to be sure of myself, raising my heart rate to 130-150? I want to participate in Zumba

No. Tachycardia can increase the workload on the myocardial tissue itself, but that's only a small fraction of the body's mass. Elevated heart rate only equals increased calorie burn under certain conditions.

Obviously, there is no way to answer your second question. I can only say that you can make sure you express your concerns to your cardiologist and insist that he/she explain IN TERMS THAT YOU CAN UNDERSTAND AND THAT DEMONSTRATE THAT YOUR CONCERNS ARE BEING TAKEN INTO ACCOUNT why you can't do more.

There may be excellent medical reasons why you need to limit your activity (I can think of a couple right away). Your doctor owes you an explanation as to what those are and he/she needs to show evidence that your concerns and wants are being considered when developing your treatment plan. You don't want to be foolish and in denial because the doctor says something you don't like, but you also want to make absolutely sure you are not just being given a "cookbook" treatment plan because that's easier for the doctor.

I hope this makes sense. It can be frustrating to have limits, but it's easier to endure if you are convinced they are justified -- and you are absolutely entitled to that justification.

And if you don't understand the first explanation -- make them do it again.

LuckyLeprechaun

Azdak...could you expand on this? You said

"Any calorie calculation that is based on heart rate is bogus to begin with, so don't worry about those. The aerobic energy cost of an activity is the same, regardless of heart rate, and that's what determines caloric burn."

Then why do I look to my HRM to tell me my calorie burn? (I'm not sarcastically asking, but genuinely don't get it) :flowerforyou:

Azdak

Azdak...could you expand on this? You said

"Any calorie calculation that is based on heart rate is bogus to begin with, so don't worry about those. The aerobic energy cost of an activity is the same, regardless of heart rate, and that's what determines caloric burn."

Then why do I look to my HRM to tell me my calorie burn? (I'm not sarcastically asking, but genuinely don't get it) :flowerforyou:

Probably not the best choice of words, so let me clarify. For right now, these remarks are going to apply to steady-state aerobic exercise.

The calories we burn during exercise result from the combination of oxygen and fuel to produce energy. The more oxygen you use, the more calories you burn. And the more intense the activity, the more oxygen you use.

When doing aerobic exercise, you have to use a certain amout of oxygen to perform the activity at a certain workload. That's called "oxygen uptake" or VO2. The VO2, or amount of oxygen needed, to perform exercise at a given level is relatively fixed.
For example, to walk 3 mph requires about 10.5 ml of oxygen per kg of body weight per minute (in other words, the VO2 for walking 3 mph = 10.5 ml/kg/min). That "energy cost" (10.5 mi/kg.min) is a fixed amount. It's the same whether you are trained or untrained, male or female, any age, etc. The calories you burn are a result of the "energy cost" X your body weight. If you run 6 mph, the energy cost is around 35 ml/kg/min.

During aerobic exercise, your heart rate and your rate of oxygen uptake (VO2) have a relatively fixed relationship. As VO2 increases, heart rate increases, and vice versa. Therefore, we can use heart rate as an indicator of oxygen uptake. This is good because heart rate is simple to measure and VO2 is not--you need expensive lab equipment to measure VO2. Example: we know that when your heart rate is at 70% of maximum, on average you are working at about 57% of maximal oxygen uptake; if you are at 85% of max HR, you are at 70% VO2 max, and so on.

HRM manufacturers use that relationship to estimate calorie expenditure during steady state aerobic exercise. The top brands--like Polar and Suunto--have done their own research studies and have developed their own algorithms to estimate calories. They have been refining their equations and interpretation for years--that's why they are considered more accurate than the "cheapo" HRMs who are getting their equations from who knows where. To be accurate, HRMs must be programmed with your weight, age, gender, maximum heart rate and maximum oxygen uptake (some use additional factors like height and activity level).

So, it's important to remember that HRMs do NOT actually measure calories. They ESTIMATE calories burned based on the relationship between heart rate and oxygen uptake. The accuracy of that estimate depends on: A) the accuracy of the user information programmed into the HRM and how closely the exercise conditions match the conditions under which the calorie estimating formulas were devised.

HR by itself cannot automatically be used as a measure of caloric burn. There are a number of conditions in which heart rate can increase, but oxygen uptake does not. These include: lifting weights, thermal stress, anxiety, illiness, sprinting, activities of daily living and others. Under these conditions, calorie counts from HRMs are highly inaccurate.

HRMs can also be inaccurate if inaccurate information is entered in the setup. Since most people never actually measure their maximum heart rate or VO2, the HRMs estimate these numbers by various means. If for some reason they are off, that can affect accuracy. If body weight increases or decreases or maximum oxygen uptake changes without updating the setup info, then accuracy will be affected.

Hope this answers your question. Let me know if you need additional info.

girlsaint

I am interested in this as well, but I also have a question. Does Tachycardia increase the amount of calories you burn at rest?
Also, in my cardiac rehab program, I was limited to a heart rate of 100, based on a stress test. My HRM was then set to alarm at that point. Problem is, now my RPE is much lower when doing more (probably a result of getting healthier. I want to go go go, but that granola-crunchin'-recumbent bike-ridin' cardiologist of mine seems to be sitting on my shoulder telling me not to overdo it?
Will I EVER be able to be sure of myself, raising my heart rate to 130-150? I want to participate in Zumba

No. Tachycardia can increase the workload on the myocardial tissue itself, but that's only a small fraction of the body's mass. Elevated heart rate only equals increased calorie burn under certain conditions.

Obviously, there is no way to answer your second question. I can only say that you can make sure you express your concerns to your cardiologist and insist that he/she explain IN TERMS THAT YOU CAN UNDERSTAND AND THAT DEMONSTRATE THAT YOUR CONCERNS ARE BEING TAKEN INTO ACCOUNT why you can't do more.

There may be excellent medical reasons why you need to limit your activity (I can think of a couple right away). Your doctor owes you an explanation as to what those are and he/she needs to show evidence that your concerns and wants are being considered when developing your treatment plan. You don't want to be foolish and in denial because the doctor says something you don't like, but you also want to make absolutely sure you are not just being given a "cookbook" treatment plan because that's easier for the doctor.

I hope this makes sense. It can be frustrating to have limits, but it's easier to endure if you are convinced they are justified -- and you are absolutely entitled to that justification.

And if you don't understand the first explanation -- make them do it again.

Thanks- I have made an appointment.