Well this is one of those really annoying things that I end up explaining a lot to people.

The ‘fat burning zone’, as is labelled on many cardio vascular machines, is supposedly the zone in which you burn more fat.

Strictly speaking the charts are right but they are also so very, very wrong. The fat burning zone on these charts relates to a percentage of maximal heart rate. These heart rate percentages are in turn based upon laboratory measures of the best level of exercise to burn the most amount of fat as a percentage.

Let’s start with the first problem. The % of heart rate that they recommend it based upon a prediction of your max heart rate. For this they use a very simple equation that your max heart rate is 220 minus your age. That would make my max heart rate 184 beats per min, yet just last week I got my heart rate up to 198 beats per minute. I don’t fit that projection. Therefore the prescribed heart rate level for my best fat loss percentage would be wrong.

It’s not just me, back when I was doing my thesis for my undergraduate degree, I studied 10 women in a raft of tests. Most noticeable was the heart rate differences but a prime example was the difference between two women of the same age.

They were both only 19 years old , so had a predicted max of 201, yet when I got them running to complete exhaustion (VO2 max test on treadmill) one peaked at 216 and the other at only 176 (and she puked in the face mask and collection apparatus (nasty clean up job).

So you can see heart rate can be hugely variable.

Secondly and most importantly the fat burning zone is a complete waste of time. I’ll show you why with a little maths…stick with me.

Let’s say you walk on the treadmill for an hour (in your fat burning zone) and you manage to burn 400 calories of which 70% were fat, you would have you burnt 280 calories of fat.

Then imagine you were to run fast (as fast as you could) for an hour on a treadmill and burnt 1200 calories, of which only 30% were made up of fat…you still burnt 360 calories of fat.

That’s 80 calories more fat, plus a whole heap more to boot!

So that’s it really, the fat burning zone is only good when viewed as a percentage not as a total amount of calories.

It’s like the old story about how survey groups used to confuse you with percentages i.e. 80% of users found that they had good results…what they didn’t tell you was that only 5 people were survey!!

We only care about total calories not percentages…the body burns calories not a percentage of those calories!

–This is an excerpt from my Fat Burn In 30 program designed for people who only have 30 minutes a day to exercise and want to lose fat.  The next course will be starting very soon, if you are interested get over to www.FatBurnIn30.com where you can get on the early notification list.

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It was purely rest and stretching today. I did a short 10 minute easy walk and then my three stretches that I think are essential for all runners. You get three video clips you can download to your PC or iPod when you download the free half marathon programme by **clicking here**

On Saturday I talked about how I took note of my heart rate whilst I was doing the 60 minute extensive interval session.

Well I have been asked a lot about heart rate and max heart rate over the years. Just last Thursday one of my clients asked me what his heart rate “should” be at considering he was cooling down after a heavy strength training session.

Well the long and the short of it is there is no firm number it should be. Your heart rate depends on what you have been doing, your fitness level (the fitter you are the quicker it comes back towards resting levels), and what your max heart rate is.

Most people will tell you that your predicted maximum heart rate is calculated by 220 minus your age, this is the one that all the equipment manufacturers use when they put the “fat burning” and “cardio training” zone charts on their machines (I’ll talk about how rubbish the “fat burning” zone is as a concept on another day).

I however know how inaccurate that calculation can be. During my undergraduate studies I did a research paper which included making subjects run on a treadmill to measure their fitness levels (this was the scientific laboratory test which the test I did on Day 3) and they had to go to the maximum effort possible.

On one of the testing days we were recording the stats from two 19 year old elite runners. One of them maxed out with a heart rate of 216! Her predicted max was 201.

The other girl actually ended up being sick into the mouth piece we were using to take measurements of her expired air. This more suggested to me that she was at her maximum output possible. Yet her heart rate maxed out at 176!

So here we have two extremely fit athletes with very divergent max heart rates.

If I was to prescribe a heart rate training zone based on only their predicted max heart rate I would be badly wrong in both cases.

I measured my heart rate when I was doing my 1 mile time trial on day 3 and it maxed at 198. I’m 34 years old and therefore should be only going up to 186. I still think there was some more in there as I didn’t collapse at the end. The last time I pushed my self to complete failure was on a rowing machine a year or two ago and my hear rate got up to 202.

So let’s look again at my heart rate whilst I was doing the RPE extensive interval session.

In my first 20 minutes it was between 145 and 156 beats per minute (bpm). 73-79% of max heart rate.

The next 20 (RPE-8) was between 155 and 165 bpm. 78-83% of max heart rate.

The last 20 minutes (RPE 6) was 125 to 140 bpm. 63-70% of max hear rate.

Now if I used the predicted max of 186 the last figure of 140 bpm would have been at 75% of my max. Now this is not a massive problem when you are using RPE for intensity levels but should act as a reminder that “generalized” programmes based around your predicted heart rate should be avoided.

I thought it was quite interesting to see that my hear rate zones quite closely matched the RPE levels I was looking to achieve (i.e. RPE 8 could be viewed as 80% and my heart rate was 78-83%).

I hope today has given you some insight into how varied heart rate training can be unless you know your true max heart rate.

Don’t forget about your free blueprint you can download **here** which also includes my three best stretches for runners video clips.

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