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The “Target Heart Rate” Myth

anthrax

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Good article on heart rate found in a musclemag web site

In the course of your training you have probably heard about your target heart rate, and how, if you stay within this rate, the gates of fat-burning heaven will open and you will automatically be whisked away to a better body.

You have probably seen those funny little “Target Heart Rate” charts, or “Your Fat Burning Zone” chart or something similar to these that tells you where you should be in order to get the most out of your training. You have also probably seen very expensive heart rate monitors available that you can wear on your wrist, waist or chest that tell you exactly what your heart rate is so that you can attempt to keep it there.

Well, I want to tell you today that aside from a few circumstances when those devices might prove useful, they are a total waste of time, money and energy for healthy individuals that can train as hard as they can stand.
Your Target Heart Rate

The "Target Heart Rate" is the level at which it is recommended you should be working in order to challenge the cardiorespiratory system and be working in the "training" or "aerobic" zone. What does this mean in English? Simply stated, it means the lowest possible heart rate that will improve cardiorespiratory fitness. Therein lies the problem with these formulas.

The most prominent and accurate means of determining your target heart rate is the Karvonen formula. This formula calculates a percentage of the heart rate reserve, which is the difference between the resting heart rate and the maximal rate.

Heart rate reserve = maximal heart rate - resting heart rate

Maximal Heart rate is the highest rate a person can attain during exercise. While an electrocardiogram test would provide the most accurate MHR, for practical application an age-predicted heart rate formula was developed.

Maximal heart rate = 220 - age

This formula is based on the assumption that one's Maximum heart rate at birth is 220 and decreases by one every year. The accuracy of determining maximal heart rate based on this formula can vary at any given age by +/- 10 beats per minute but it provides a quick and easy way of determining this value without complex tests or mathematics.

Resting Heart rate is the rate at which your heart beats at rest. It is recommended that this rate be taken immediately upon waking, counting the pulse for a full 60 seconds, 3 mornings in a row and averaging the counts.

Determining The Target Heart Rate Ranges

Using the Karvonen formula, the generally accepted heart rate ranges are between 60% to 80% of the maximal heart rate reserve.

So, your Target heart rate = % intensity X heart rate reserve + resting heart rate

Here's how it would be calculated for a 45 year old with a resting heart rate of 80 and an age predicted maximal heart rate of 175 at an 80% intensity level of maximum heart rate reserve:

175 (age predicted MHR)
- 80 (resting heart-rate)
---------------------------------
= 95 (heart rate reserve)
X .80 (intensity level)
---------------------------------
= 76.00
+ 80.00 (resting heart-rate)
---------------------------------
= 156.00 (target heart rate for 80% exertion)


It was recommended that the formula be applied to both ends of the range, 60% and 80%, to determine the target heart rate training zone.

To allow people easy reference for their intensity levels, Target Heart Rate Charts are generally posted in gyms and especially in the cardio rooms of gyms. See the Heart Rate Chart for an example.

I don’t know about you, but that was more work than I am willing to do to determine how hard I should be exercising! Even looking at the chart can be confusing as well as misleading for someone who is healthy and capable.

Lose Fat, and Get In Shape WITHOUT Charts and Numbers!

I have to admit that for certain people knowing what your heart rate is can be invaluable information. For instance someone with heart problems, or someone that is recovering from heart surgery usually has specific guidelines set up by their doctor as to how much stress they can put on their heart. Also, certain athletes like marathon runners, often measure their heart rate as part of their training to better pace themselves for a race.

Aside from these and others specific needs, for most of us, knowing your heart rate is useless information, and information that can often lead to undertraining. Yes, that’s right UNDERTRAINING. More on that later.

First off, I wanted to go over the fact that you will not burn more fat training in one zone vs. another. Yes, I know, “they say” that training in such-and-such a zone you will burn a higher percentage of fat as fuel. What “they” don’t tell you is that once you are done with that training, and you eat, you will replenish what was lost during that workout, and if the calorie deficit was not enough, whether it was in a specific training zone or not, you will not lose weight regardless.

The following was taken from “A Practical Approach to Strength Training” by Matt Brzycki and explains in detail what I am getting at:

“A greater percentage of carbohydrates are used as an energy source during exercise of higher intensity. Conversely, a greater percentage of fats are used as an energy source during exercise of lower intensity… These physiological facts have led to the mistaken belief that the “fat-burning” (or low intensity) exercise is better than “carbohydrate-burning” (or high intensity) exercise when it comes to losing weight, “burning” fat and expending calories…

… In truth, even though the percentage of calories used from fats are greater during low intensity exercise, the total number of calories expended during high intensity exercise is greater (Bryant, Peterson and Hagen 1994)…

… Based upon the ACSM formulas for determining oxygen uptake and caloric expenditure during walking and running, a 165-pound man who walks 3 miles in 60 min. will utilize roughly 4.33 cal./min. Over the course of his 60-minute walk, his total caloric usage would be about 260 calories. If that same individual ran those 3 miles in 30 minutes, he would use about 13.38 cal./min. In this case, he would have expended about 401 total calories during his 30-minute run. So exercising at a higher level of intensity used up significantly more calories than exercising at a lower level of intensity (401 calories to 260). This is true despite the fact that the activity of the lower intensity was performed for twice as long as the activity of the higher intensity…

… The calculations have been corroborated by research in the laboratory… The intent behind advocating low intensity exercise of long duration is to enhance safety and improve compliance in the nonathletic population. However, low intensity exercise is not more effective for fat loss than high intensity exercise (Bryant, Peterson and Hagen 1994; Porcari 1994). In order to lose weight, more calories must be expended than consumed to produce a “negative calorie balance” or calorie deficit. Whether carbohydrates or fats are used to produce this negative balance is immaterial. A caloric deficit created by the selective use of fat as and energy source doesn’t necessarily translate into greater fat loss compared to an equal calorie deficit created by the use of carbohydrates as an energy source… Finally, it should also be noted that low intensity exercise usually doesn’t elevate the heart rate enough in healthy adults to produce an aerobic conditioning effect…”

So what is my point with all of this? Quite simply, paying attention to the heart rate charts and trying to stick within a “fat burning zone” is illogical, and counterproductive. You will lose more fat training at a higher intensity for a shorter period of time, and that is a known fact and as simple as it gets. Yes, it might be more uncomfortable to do this, you will sweat more, expend more energy, feel more tired afterwards, etc., but in the long run, it will do more for you.

My second point ties in nicely to this last point. Namely, if you try and stay in these predetermined zones, you are cutting yourself short, and potentially UNDERTRAINING yourself. You will not only lose more fat by training at a higher intensity, but you will also get your heart in better shape as well which will lead to better training in the weight room and ultimately, lead to better results overall.
We are all masters of our own destiny. We know if we are training as hard as we can. When you are on that cardio machine, ask yourself: Is this as hard as I can make this? Can I raise the level any more? Only you know the real answers to these questions. Only you know if you are pushing yourself to the limit. Only you know if you are going to leave the gym that day and feel victorious, or merely accomplished.

So, forget about those damn heart rate charts and start paying more attention to yourself and how you feel. If you are a healthy individual with no medical concerns, then you should have no boundaries as to how hard you can push yourself. If you were ever in sports do you remember training so hard, running so fast or exerting yourself so much that you thought you were going to die? Did you? Exactly. You not only didn’t die, but you got in better shape because of that effort. That is the point that I am making.

I am not suggesting that you try and pass out every time to step into the gym, but there is no harm in pushing yourself beyond what is comfortable, and in the process get in better shape physically, cardiovascularly, and lose more fat than ever before. In order to do this though, you need to throw out all your preconceived notions about fat burning, and all your trepidations about training beyond what is “comfortable”. No one ever got a great body by training comfortably.
 
Very cool post, thanks. I'll send some Karma on the way. I always saw better results w/ higher intensity cardio BTW. But it's always good to do a session here and there of lower intensity, problem is finding the time for all that cardio.
 
Thanks for the info. I agree.

I'm 20, which puts my fat burning rate at about 135bpm. But when I get on the treadmill and reach 135, I'm not even breathing any heavier than when I'm sitting there doing nothing. Nor am I even close to breaking a sweat. In fact, I realise that the speed on the treadmill which keeps me at 135bpm, is no faster than I the speed I walk around at every day. Since I spend 30 minutes walking to and from the gym, and additional time spent walking everywhere else.... I would be doing a whole lot of cardio.

The recommended BPM does absolutely nothing for me. I have to go well over it to get any sort of training effect.
 
Anthrax-
I am a huge advocate of cardio and in general I agree with your post. Most of those charts are useless. Most people who read these boards are fit enough that these charts are terribly inaccurate. I am 27 and my max is 198.

At certain exercise intensity levels your body does burn fat, but this really only comes into play after about :30 of cardio exercise so IMO this tends not to be useful for 98% of the people on this board or in most health clubs. And the HR zone that burns more fat is the aerobic zone and of course this will vary for every individual. All those zones are really for improving cardiovascular fitness like you said. The best way to figure HR zones is to hit your max HR and figure your zones from there. Hitting your max isn't recommeneded for most people so these formulas come into play. It is hard to hit max HR anyway as you have to be in pretty good condition to be able to rev your internal motor that high.

Personally I know I burn lots of BF when I go out and do LONG moderate to high intensity rides (75-110 miles). I also know I burn more fat if the ride or race is intense and shorter.

I think people generally don't push themselves hard enough when they do cardio. I see so many people at the gym WALKING on the stairmaster-just fucking walk outside! I need the stairmaster as I am going to RUN on the mofo! Go hard or go home.

FHG
 
At certain exercise intensity levels your body does burn fat, but this really only comes into play after about :30 of cardio exercise so IMO this tends not to be useful for 98% of the people on this board or in most health clubs.
I agree. That's why I do my cardio post weight training because I am depleted by then and my body will use fat for fuel.
 
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