HRM while strength training... can this be right???

StrengthInPain

So i went to the gym today, and did my 20 minute run and 10 minute incline walk. Then I went to do my weight lifting, so i reset my HRM and i lifted for 60 minutes... hit every major muscle group and then some. I did the normal 3 sets of 10 for each one. When i was done, i stopped my HRM and it said i burned 400 calories?!?!?!?!! Can that really be correct? It said my average HR was 124 and my max HR was 142. Has anyone else had a similar experience?? Or can any of the experts explain? I already have tons of categories left over and i know there's no way i'm eating the 400 calories anyway, i'm just interested as to why?

EKarma

I would trust your HRM. I also noticed that I burn more strength training. I know my HR really gets up there when I do lift. But either way, I would trust the HRM.

firegirlred

Check out my exercise log. You'll see that I easily burn 200 in 45 minutes. I don't know your stats, but hubby burns twice what I do for the same workout.

imagymrat

Yup, it's probably right. I burn a ton more cals weight training then I do in my cardio sessions...isn't it nice to know that you don't need to be running your a** off to burn calories? :laugh:

StrengthInPain

Check out my exercise log. You'll see that I easily burn 200 in 45 minutes. I don't know your stats, but hubby burns twice what I do for the same workout.

I thought about 200 for the hour would be about right... I'm 5'5" 160 lbs. I use the weight machines, and lift between 40 and 50 for most arm exercises, and between 60 and 70 for most legs. I'm wondering if maybe my heart rate stayed elevated from my run, and it affected how my HR and calories were calculated.. I tried the run first this time because if i do the run at the end i'm too tired to put a full effort in.. I'm thinking i may try to do the weights first next week and see what happens with my HR and calories.

Azdak

Heart rate and HRMs cannot be used as a reliable monitor of calories burned during strength training.

http://www.myfitnesspal.com/blog/Azdak/view/hrms-cannot-count-calories-during-strength-training-17698

firegirlred

Your heart rate is a very exact measure of how hard your body is working. Your cells need oxygen and must release carbon dioxide. The harder your cells work, the harder faster your heart rate, the harder you breathe. I have no doubt that you really burned that many calories. IF you have a quality hrm, it took into account your heart rate, age, gender, height, weight, and hopefully your VO2 max. Don't second guess yourself, you are doing a good job at the gym. Trust your hrm and keep up the good work!

Azdak

Your heart rate is a very exact measure of how hard your body is working. Your cells need oxygen and must release carbon dioxide. The harder your cells work, the harder faster your heart rate, the harder you breathe. I have no doubt that you really burned that many calories. IF you have a quality hrm, it took into account your heart rate, age, gender, height, weight, and hopefully your VO2 max. Don't second guess yourself, you are doing a good job at the gym. Trust your hrm and keep up the good work!

Heart rate is an exact measure of how hard your *heart* is working. The rest of the body--not always so exact. Someone sitting in a sauna, for example, will experience an increased heart rate, without a corresponding increase in VO2. Same with a fever, and a number of other conditions.

Same with lifting weights. The heart rate increase experienced during lifting weights is usually not associated with the same degree of VO2 increase experienced during cardiovascular exercise. That is because the increased heart rate is more pressure-driven than volume-driven and it is the increased cardiac output that drives VO2 and calorie expenditure, not just heart rate alone. During heavy weight lifting, the increase in heart rate is not accompanied by an increase in cardiac output.

Strength training is essential to weight loss and the process (during exercise, immediate post exercise, during recovery) does burn significant calories (perhaps even more than cardio). It's just that HRMs cannot reliably capture that data and HRM calorie numbers derived from strength training are not reliable.

fozzy33

Azdak I did not realize all of this, but I kinda did blindly, if you know what i mean. I make sure I get all my daily calories burned in Cardio (About an hour per day) and when I hit my number of calories burned through cardio its THEN i start weights/strength training.

Does that make sense? LOL

Michelle

Azdak

Azdak I did not realize all of this, but I kinda did blindly, if you know what i mean. I make sure I get all my daily calories burned in Cardio (About an hour per day) and when I hit my number of calories burned through cardio its THEN i start weights/strength training.

Does that make sense? LOL

Michelle

There are plenty of different ways to be successful. The problem is that there is a tendency to put too much faith in the assumed accuracy of heart rate monitors. I always find it ironic that so many people will dismiss the calorie readings from a machine out of hand, but accept as absolute truth a number from a cheap piece of crap they bought at walmart. I just try to rein in some of the hyperbole. Machines--esp from a manufacturer such as Life Fitness--are not as inaccurate as people think and HRMs are not nearly as accurate as most people here believe.

jayme03

"I always find it ironic that so many people will dismiss the calorie readings from a machine out of hand, but accept as absolute truth a number from a cheap piece of crap they bought at walmart." -Azdak

I'm pretty sure that some of us, like myself are not buying "cheap peieces of crap" HRM's from Walmart. I definitely agree with you as far as the strength training piece goes and how it doesn't compare to calories burned while doing cardio, but I DO trust that my HRM is more accurate than the machines (treadmill, elliptical etc) and that is because I have a quality HRM and it just makes sense.

firegirlred

Your heart rate is a very exact measure of how hard your body is working. Your cells need oxygen and must release carbon dioxide. The harder your cells work, the harder faster your heart rate, the harder you breathe. I have no doubt that you really burned that many calories. IF you have a quality hrm, it took into account your heart rate, age, gender, height, weight, and hopefully your VO2 max. Don't second guess yourself, you are doing a good job at the gym. Trust your hrm and keep up the good work!

Heart rate is an exact measure of how hard your *heart* is working. The rest of the body--not always so exact. Someone sitting in a sauna, for example, will experience an increased heart rate, without a corresponding increase in VO2. Same with a fever, and a number of other conditions.

Same with lifting weights. The heart rate increase experienced during lifting weights is usually not associated with the same degree of VO2 increase experienced during cardiovascular exercise. That is because the increased heart rate is more pressure-driven than volume-driven and it is the increased cardiac output that drives VO2 and calorie expenditure, not just heart rate alone. During heavy weight lifting, the increase in heart rate is not accompanied by an increase in cardiac output.

Strength training is essential to weight loss and the process (during exercise, immediate post exercise, during recovery) does burn significant calories (perhaps even more than cardio). It's just that HRMs cannot reliably capture that data and HRM calorie numbers derived from strength training are not reliable.

Azdak-I think you dismiss the accuracy of a GOOD hrm too easily. I read your blog post. I agree that there is a degree of intrathoracic pressure that accompanies the lifting phase, but heart rates tend to stay up after the lift for a degree of time that does not correspond appropriately with that pressure. In addition, the stimulation of the vagus nerve would drive the heart rate the opposite direction, sometimes a much stronger influence than an increase in intrathoracic pressure and a much more common event during a lift.

You make a good point in your blog to mention the fact that hrm's use data collected from energy expenditure with repetitive motion studies, but a heart rate is a product of the body's degree of effort. A good heart rate monitor will use the "bottom line" (VO2 and resting heart rate) to develop a highly accurate measure of energy expenditure. Any person with a good head on their shoulders will dismiss the "average" calorie expenditure given to them by a machine because it does not take enough factors into consideration.

I would infer to be accurate how many calories burned doing a weight workout. And the reason is this: your cells have reliable, reproducible gas exchange rates and when the "waste" level goes up, your heart rate goes up to accommodate. Weight lifting produces "waste." Your body is driven (typically and under normal resting and exercise circumstances) not by a need for oxygen, but for a need to excrete carbon dioxide or "waste" (in a healthy person anyway.) And in order to appropriately compensate for the calories used during that process (weight lifting or cardio), I would always wear a heart rate monitor. Your cells become more efficient through exercise, and your resting heart rate drops as they do.

Hydration status affects that calorie burn because the heart has to work harder to pump less fluid around the body for waste excretion.

You mention that someone with a fever or sitting in a sauna experiences a rise in heart rate without a rise in VO2. I disagree with that somewhat. Someone with a fever or in a sauna will experience that increase in heart rate because their body is at work. It takes energy to fight off an infection or keep a body cool. I don't agree that someone with a fever or a sitting in a sauna burns the same number of calories as someone healthy sitting in front of that tv. Not saying that you should wear a HRM during these times so you can eat more!!! Heart rate is a very good indicator of how the body is working. You just have to know additional data when looking at that heart rate, like resting heart rate, and many HRM's don't consider that. High end HRM's usually do. Many times better than people.

mworld

Azdak, from your blog:

"So, unlike aerobic exercise, the increased heart rate during strength training DOES NOT reflect either an increase in oxygen uptake or a significant increase in caloric expenditure. Moving quickly from machine to machine to keep the heart rate elevated does not change this fact. It is still a pressure load, not a volume load."

If I am reading you right. You essentially claim that circuit training will not increase your calorie use when you talk about moving from machine to machine quickly?

Azdak

Azdak, from your blog:

"So, unlike aerobic exercise, the increased heart rate during strength training DOES NOT reflect either an increase in oxygen uptake or a significant increase in caloric expenditure. Moving quickly from machine to machine to keep the heart rate elevated does not change this fact. It is still a pressure load, not a volume load."

If I am reading you right. You essentially claim that circuit training will not increase your calorie use when you talk about moving from machine to machine quickly?

No, i was referring to some studies i have seen on traditional strength training where you move quickly from machine to machine. (Traditional sets of, say, up to 10 RM).

I don't know if you stopped reading early (understandable--I know I write long..... ) but later in the article, I specifically addressed circuit training. It is difficult to make a single comment here about circuit training, since there are so many different kinds of routines. I go into more detail in the blog.

The circuit training question is even more complex now that even 10-15 years ago, once again, because there are so many different types of routines, and intensity plays a key role, and we now understand that, with some routines, what happens AFTER the exercise session and during recovery burns as much if not more energy as during the session.

I also think it is important to emphasize that this whole subject is very much a sideshow. I mean we are focusing not on whether a routine is effective or not, but if a HRM calorie count is most accurate and how to count calories in these routines. A lot of new routines are GREAT for burning calories--we just don't have a good way of keeping count.

mworld

Azdak - yes, i did stop short when I came to that paragraph because it was a bit puzzling. So now I have read the rest and see that you did go detail that part out .

So what I don't see are practical suggestions from you on how to keep count, especially on sites like these where the count can be critical to peoples' success with the way they attack their eating habits. Obviously, not accounting for it at all is not really satisfactory for people on here.

I can derive from your talk about a HRM most likely overestimating strenght training by as much as 30-35% that if someone wanted to take the most conservative approach with respect to accuracy that they would just derate what their HRM tells them by 35% and be assured that they can eat/plan their meals around this figure with confidence. Or maybe even just say 20% and figure that the pluses and minuses based on intensity from workout to workout will even themselves out?


....I mean, that's what this is all really about, people being able to use these tools to help them navigate through their daily diets effectively.