Beta Blockers and Exercise

zezelryck

When I first started to use MFP I soon realised that the burns I was getting from exercise seemed to be way higher than I expected. I trawled the forum and getting a heart rate monitor seemed a lot more accurate solution to my problem. After using it a while I noticed my burns where a third of what MFP had stated. I then found out it was down to my beta blockers, which basically trick my heart into beating slower. I am therefore seemingly burning more Kcals than with a HRM and less than MFP. I have found a swimming calories counter which seems to give results halfway between the two, but now I feel guilty using the results from that calculator. Does anyone have an opinion on this?

Counter can be found at:

http://www.swimmingcalculator.com/swim_calories_calculator.php

Hozman121

This is a great question. I never thought of those on Beta blockers not being able to reach their true Max heart rate or how this changes calories burned via HRM or even the read on a cardio machine at a gym.

IMO I would think the calories burned would truely be higher than what monitor shows. You are working as hard as say a 180 max heart rate but the Beta blocker will only allow you to get to say 150....not exact just example.

At work we have to take a PT test every year and those who are on Beta Blockers have to go get stress tests done at cardiologist cause they will never peak at their maximum heart rate.

kendallvon

All I know is that the calorie burn here is much lower than the site I used for years. I'm on a beta blocker, too, so I'm interested in what you come up with.

Azdak

Calories burned during exercise are based on weight x the absolute workload of the activity. They are NOT based on heart rate. We use heart rate as a guide because, under certain conditions, changes in heart rate reflect changes in workload, and, with certain information about the individual, heart rate be used to (roughly) estimate oxygen uptake. However, heart rate per se, DOES NOT drive calorie expenditure--just like putting a thermometer in your fridge doesn't change the temperature.

HRMs are "dumb" devices--they are programmed with equations that are based on assumptions, and they interpret the electronic signals based on those assumptions and equations. But a HRM CANNOT determine the origin of the electronic signals--it assumes that the user understands how the device works and knows what they are doing. You could strap a chest strap to a fence post along with a signal generator and it would give you a calorie reading.

If you are on a beta blocker, your heart rate response "scale" is altered by the medication. Instead of a resting HR of 70 and a max HR of 170, your "scale" might now be rest HR 56 and Max HR 126. While the "scale" is different, your metabolic response to exercise is still mostly the same (although your max ability might be lowered slightly). You are still burning mostly the same calories as before. But since the dumb HRM still has your old "scale" programmed into it, it will reflexive assume you are not working as hard (since HR is lower) and reflexively spit out a lower calorie number.

In the old days when they would just whack people up with a big dose of Inderal, it was possible to do a symptom-limited grades exercise test while taking the medication and get a decent idea of the new HRmax. You could then determine an exercise target HR. Now with the wide array of meds, there is not as much of a consistent response and most doctors have no interest or expertise in conducting functional exercise testing.

Long story short: if you are on a beta blocker, then using a HRM to estimate calories is even more useless than usual. Good news is that those lower numbers are crap and can be ignored.

zezelryck

Calories burned during exercise are based on weight x the absolute workload of the activity. They are NOT based on heart rate. We use heart rate as a guide because, under certain conditions, changes in heart rate reflect changes in workload, and, with certain information about the individual, heart rate be used to (roughly) estimate oxygen uptake. However, heart rate per se, DOES NOT drive calorie expenditure--just like putting a thermometer in your fridge doesn't change the temperature.

HRMs are "dumb" devices--they are programmed with equations that are based on assumptions, and they interpret the electronic signals based on those assumptions and equations. But a HRM CANNOT determine the origin of the electronic signals--it assumes that the user understands how the device works and knows what they are doing. You could strap a chest strap to a fence post along with a signal generator and it would give you a calorie reading.

If you are on a beta blocker, your heart rate response "scale" is altered by the medication. Instead of a resting HR of 70 and a max HR of 170, your "scale" might now be rest HR 56 and Max HR 126. While the "scale" is different, your metabolic response to exercise is still mostly the same (although your max ability might be lowered slightly). You are still burning mostly the same calories as before. But since the dumb HRM still has your old "scale" programmed into it, it will reflexive assume you are not working as hard (since HR is lower) and reflexively spit out a lower calorie number.

In the old days when they would just whack people up with a big dose of Inderal, it was possible to do a symptom-limited grades exercise test while taking the medication and get a decent idea of the new HRmax. You could then determine an exercise target HR. Now with the wide array of meds, there is not as much of a consistent response and most doctors have no interest or expertise in conducting functional exercise testing.

Long story short: if you are on a beta blocker, then using a HRM to estimate calories is even more useless than usual. Good news is that those lower numbers are crap and can be ignored.

zezelryck

Sorry for the double post. Thanks Adzak for that explanation.

meshashesha2012

you can still use your HRM, just adjust the min and max numbers manually. heybales has a really good thread (sorry i dont have a link) that gives good information about how your hrm should be set up so that it's less out of the box/one size fits all and more in line with your specific body.

of course it's still an estimate but the estimate gets a bit better when the numbers are set up correctly

Azdak

you can still use your HRM, just adjust the min and max numbers manually. heybales has a really good thread (sorry i dont have a link) that gives good information about how your hrm should be set up so that it's less out of the box/one size fits all and more in line with your specific body.

of course it's still an estimate but the estimate gets a bit better when the numbers are set up correctly

It's definitely better. Whether that is still in any way helpful is questionable. The problem is that, without a symptom-limited graded exercise test, you don't really know HRpeak. And since dosages and individual responses vary, there is no equation that can be applied (there is published literature that suggests you can reduce HRmax by "x%" but those studies were limited when they were done and are outdated now).

In addition, you have a wide variety of beta blockers available, some selective, some non-selective, some are multiple dose and some are single dose. And if that weren't enough, despite claims to the contrary, drug levels vary throughout the day. I have seen individuals on drugs such as atenolol have a heart rate response to exercise that can vary by 30 beats/min depending on the time of day they exercise.

So I guess it's up to each person to determine what is a "reasonable" estimate, but those are the facts about beta blockers that people should know before they start estimating.

sjaplo

When I first started to use MFP I soon realised that the burns I was getting from exercise seemed to be way higher than I expected. I trawled the forum and getting a heart rate monitor seemed a lot more accurate solution to my problem. After using it a while I noticed my burns where a third of what MFP had stated. I then found out it was down to my beta blockers, which basically trick my heart into beating slower. I am therefore seemingly burning more Kcals than with a HRM and less than MFP. I have found a swimming calories counter which seems to give results halfway between the two, but now I feel guilty using the results from that calculator. Does anyone have an opinion on this?

Counter can be found at:

http://www.swimmingcalculator.com/swim_calories_calculator.php

If you are on beta blockers for blood pressure - I would ask your doctor about ACE inhibitors - they've held my bp in check for over 10 years now. I was given the option of beta blockers but didn't think they would go well with running. If you are exercising strenuously they can interfere with your bodies natural reactions as you have already discovered.

pmr545

I suggest that you consult with your doctor.... you wouldn't want to trigger a heart situation by accident.

zezelryck

Some really useful and thought provoking advice here. Thanks all for your input. I have a visit on the 24th of February with my heart specialist regarding having an operation to repair an RVOT, I'm told that involves open heart surgery. I was tested for a replacement valve that would be threaded up through a vein in my leg into my heart but told I was unsuitable for that for whatever medical reason (as you can tell I am a total layman).