To push or not to push? Heart rate confusion..

katieai

First off, I apologize if this topic has been discussed before. I tried searching but couldn't come up with the correct information.

This is not my first ever attempt at weight loss, but this is my first time I've included exercise in my efforts. I workout five days per week, running stairs and doing body weight circuits. I do not belong to a gym and it's incredibly hot this time a year where I live, so almost all my exercise is performed indoors. Anyway, onto my real dilemma. I've been tracking my heart rate during exercise, as well as when I'm resting, to try to determine where my personal "fat burn zone" is. When I research target heart rate zones, I come up with quite a bit of conflicting information. Some say that one must stay within their personal "fat burn" or "cardio" zone to burn fat most efficiently, while others state that these claims are bogus and the harder you push, the more calories burned. But then the other sources argue that when you approach your max heart rate, you begin to burn muscle rather than fat.

My resting heart rate is higher than most, usually hovering between 75 and 85 (it's been as high as 90) beats per minute (I am on a prescribed medicine that is a bit stimulating). A few of the calculators I've tried seem to give me roughly the same target heart rate zone for fat burning: 149-161 beats per minute. When I run stairs and am actively monitoring my heart rate, I will often need to stop for a minute to allow my heart rate to drop from the high 170's back into that specific range. My conundrum is that anything below 160 BPM feels too easy, like I'm not working hard enough? To really begin sweating and breathing hard, my heart rate resides in the 170s (which is too high, according to these calculators).

So which is it? Should I continue to slow myself down and stop every few minutes to maintain this target heart rate zone for fat burning, or should I just go for it and forget about the heart rate thing? Does it matter that my resting heart rate is higher to begin with? Does that have any impact on my target heart rate?

Here's my stats:
5' 4.5", female 25 years old
SW: 200
CW: 189
GW: 150

I appreciate the help!

3dogsrunning

Forget fat burning zones. Most of the zones are based off of overgeneralized info. Even assuming you are able to correctly figure your zones, and assuming there are actually fat burning zones, consider this - the "fat burning" zones are low intensity. You burn a higher amount of "fat" calories while in this zone, but overall a low amount of calories. In the cardio zone, you burn a lower percent of "fat" calories, but overall, your have a much higher calorie burn so even at the lower percent, you still burn more.

Perform to an intensity you can complete the workout but it is challenging.

xsmilexforxmex

http://sportsmedicine.about.com/od/Exercise-Metabolism-Energy/a/Does-The-Fat-Burning-Zone-Burn-Fat-Faster.htm

There's a graph about half way down... If you're trying to improve, going high-intensity is great. If you're trying to build endurance, lower intensity. All depends on goals. otherwise it's all percentages... What the graph doesnt show is that some of those calories from each one are lean mass, so remember to do strength training.

sijomial

There are benefits for athletic performance (particularly endurance sports) in heart rate zone training but it's a lot more complex than fat burning or cardio zone.

For fat loss it's just calorie burn (assuming that results in a calorie deficit!!) that matters.

The highest proportion of fat burned is at really, really low heart rate but at that rate you aren't actually burning many calories at all. For perspective my min/max HR is 48/176. I'm running on solely fat up to about 85 bpm, just warming up basically.
At about 160bpm I'm just about totally fuelled by carbs. Between those points it's a blend of both.

Here's how they test fuel sources when you are hooked up to a breathing tube in a sport science lab....

Respiratory exchange ratio
The respiratory exchange ratio (RER) is the ratio of carbon dioxide produced from
the quantity of oxygen inhaled. This ratio can be used to estimate the source of fuel
or mixture of fuels the individual is relying on. Values range from 0.7, indicating total
reliance on fats as a fuel source, 0.85 being a mixture of fats and carbohydrates,
1.00 being total dependence on carbohydrate and anything above 1.00 indicating the
individual is now relying on anaerobic sources to meet their energy demands.


As for this....

But then the other sources argue that when you approach your max heart rate, you begin to burn muscle rather than fat.

This is incredibly hard to achieve for normal people. If you have never done a max heart rate test you have no idea how hard it is and how short a duration you can actually maintain that kind of maximal effort.

3dogsrunning

There are benefits for athletic performance (particularly endurance sports) in heart rate zone training but it's a lot more complex than fat burning or cardio zone.

For fat loss it's just calorie burn (assuming that results in a calorie deficit!!) that matters.

The highest proportion of fat burned is at really, really low heart rate but at that rate you aren't actually burning many calories at all. For perspective my min/max HR is 48/176. I'm running on solely fat up to about 85 bpm, just warming up basically.
At about 160bpm I'm just about totally fuelled by carbs. Between those points it's a blend of both.

Here's how they test fuel sources when you are hooked up to a breathing tube in a sport science lab....

Respiratory exchange ratio
The respiratory exchange ratio (RER) is the ratio of carbon dioxide produced from
the quantity of oxygen inhaled. This ratio can be used to estimate the source of fuel
or mixture of fuels the individual is relying on. Values range from 0.7, indicating total
reliance on fats as a fuel source, 0.85 being a mixture of fats and carbohydrates,
1.00 being total dependence on carbohydrate and anything above 1.00 indicating the
individual is now relying on anaerobic sources to meet their energy demands.


As for this....

But then the other sources argue that when you approach your max heart rate, you begin to burn muscle rather than fat.

This is incredibly hard to achieve for normal people. If you have never done a max heart rate test you have no idea how hard it is and how short a duration you can actually maintain that kind of maximal effort.

To be clear, I agree as well, my answer was in relation to the weight loss/fat loss aspect only. HR training does have value. And I would still recommend more precise ways of establishing zones rather than general charts.

sijomial

To be clear, I agree as well, my answer was in relation to the weight loss/fat loss aspect only. HR training does have value. And I would still recommend more precise ways of establishing zones rather than general charts.

Completely agree on the value of HR zone training for performance - I use it for my cycling training.

Just wish HRM manufacturers would catch on and get back to what HRMs are actually for - a training aid not a calorie counter or diet aid.....

SueInAz

From what I've read you burn a higher percentage of calories from fat when you stay in the "fat burning zone" but a higher number of calories, and therefore more fat calories overall, when your heartrate is higher. My advice is to not worry so much about a "fat burning zone" heartrate but to simply workout at a heart rate that is comfortable for you as well as meets your fitness goals as described by other posters.

As far as your heart rate compared to your intensity level, my resting heart rate is around 60-65 but when I run my heart rate usually hovers in the 170s to low 180s. That's the same whether I'm at the end of a half marathon or just finishing a 5K. I'm 48, about 5'3" and I haven't keeled over yet. I do have a tendency to back off a bit when I hit around 183 because I can tell that's about the max for me, expecially for longer runs.

3dogsrunning

To be clear, I agree as well, my answer was in relation to the weight loss/fat loss aspect only. HR training does have value. And I would still recommend more precise ways of establishing zones rather than general charts.

Completely agree on the value of HR zone training for performance - I use it for my cycling training.

Just wish HRM manufacturers would catch on and get back to what HRMs are actually for - a training aid not a calorie counter or diet aid.....

Preach!

katieai

Okay so it sounds like I was over-complicating this thing. Run until I'm sweaty and out of breath, but stop before I see stars and/or vomit. Got it, easy enough! Thanks guys!

QuietBloom

Perceived rate of exertion can be misleading IMO. Since you have a heart rate monitor, why not determine YOUR maximum HR and then your zones based on that? I'll leave this here:

http://www.runningforfitness.org/faq/hrmax

Mykaelous

From the years of reading research, to university nutrition and fitness classes, and from personal experience what I have found is that your body metabolizes energy at a certain rate. Normally at rest if you are eating your TDEE your body burns fat at the same rate that you body builds it so you stay the same weight. If you begin to exercise instead of building the fat your body uses that excess energy to fuel your exercise. Now your body is only capable of metabolizing fat at a certain rate(although you can increase your body’s ability to metabolize fat over time with conditioning), lets just say unscientifically that the normal person can metabolize 200 calories of fat per hour(Depends on genetics and conditioning). When your body needs energy it first uses energy that is already present in your bloodstream as this is the "cheapest" source of energy, afterwards it taps into fat stores, and after that it goes to muscles, and finally organs. Now you have to think of this as a sliding scale. Your body is constantly breaking down and building cells, millions a day. What changes is the ratio. So you might go from 80% digested food, 15% stored fat, and 5% muscle to 60% digested food 30% fat, and 10% muscle when your heart rate is in the "fat burn" zone. When you push into the cardio zone you might be getting 50% from digested food, 35% fat, and 15% muscle. Catabolic breakdown of cardiovascular tissue is required for anabolic growth during your sleep(because your body will overcompensate for the muscle breakdown), except when you body is at a caloric deficit which disallows your body from effectively rebuilding the broken down muscular tissue which can lead to muscle loss. This is why you will hear these stories from people who are cutting calories suddenly not being able to lift the same weight they did 1 month ago.

So if your goal is weight loss my suggestion is to stick to your "fat burn" zone for a longer period of time, rather than pushing into the cardio zone for a shortened period of time. You may burn more fat calories overall at a higher heart rate, but in my opinion the increase catabolism of muscle tissue is not worth it in the long run.

brianpperkins

From the years of reading research, to university nutrition and fitness classes, and from personal experience what I have found is that your body metabolizes energy at a certain rate. Normally at rest if you are eating your TDEE your body burns fat at the same rate that you body builds it so you stay the same weight. If you begin to exercise instead of building the fat your body uses that excess energy to fuel your exercise. Now your body is only capable of metabolizing fat at a certain rate(although you can increase your body’s ability to metabolize fat over time with conditioning), lets just say unscientifically that the normal person can metabolize 200 calories of fat per hour(Depends on genetics and conditioning). When your body needs energy it first uses energy that is already present in your bloodstream as this is the "cheapest" source of energy, afterwards it taps into fat stores, and after that it goes to muscles, and finally organs. Now you have to think of this as a sliding scale. Your body is constantly breaking down and building cells, millions a day. What changes is the ratio. So you might go from 80% digested food, 15% stored fat, and 5% muscle to 60% digested food 30% fat, and 10% muscle when your heart rate is in the "fat burn" zone. When you push into the cardio zone you might be getting 50% from digested food, 35% fat, and 15% muscle. Catabolic breakdown of cardiovascular tissue is required for anabolic growth during your sleep(because your body will overcompensate for the muscle breakdown), except when you body is at a caloric deficit which disallows your body from effectively rebuilding the broken down muscular tissue which can lead to muscle loss. This is why you will hear these stories from people who are cutting calories suddenly not being able to lift the same weight they did 1 month ago.

So if your goal is weight loss my suggestion is to stick to your "fat burn" zone for a longer period of time, rather than pushing into the cardio zone for a shortened period of time. You may burn more fat calories overall at a higher heart rate, but in my opinion the increase catabolism of muscle tissue is not worth it in the long run.

The "fat burn zone" doesn't do much for the beginner nor does the normal person exercise anywhere near long enough for aerobic activity to turn to a catabolic process .... at least that is what the findings of years of research conclude. You contradict yourself from post to post, thread to thread.

hermann341

It seems to me that working out at a level you can sustain longer is the better way to go. I tend to run at what is typically considered about 75% to 80% for my age, though I will usually push harder at the end of my runs in order to be able to sustain higher heart rates when I'm tired.

Azdak

To be clear, I agree as well, my answer was in relation to the weight loss/fat loss aspect only. HR training does have value. And I would still recommend more precise ways of establishing zones rather than general charts.

Completely agree on the value of HR zone training for performance - I use it for my cycling training.

Just wish HRM manufacturers would catch on and get back to what HRMs are actually for - a training aid not a calorie counter or diet aid.....

Except that they would lose about 95% of their market share.