The Fat Burning Zone Myth.
In my 10 odd years (yes they have been very odd) working in the Fitness Industry I’ve come across many ideas that seemed valid at first glance but upon deeper contemplation they quite simply don’t make sense. One of these is the Fat Burning Zone.
The theory behind this Zone is this.
Exercise at 60-65% of your Maximal Heart Rate (MHR) and, of the calories you expend, you’ll be burning 50% as Fat Calories.
Exercise at 80-85% of MHR and you’ll burn 40% of Calories as fat.
Sounds good doesn’t it – don’t have to exercise as hard and burn off a higher percentage of fat. Here's the thing, it's all based on percentage.
Here’s a basic chart of how the Fat Burning Zone fails to live up to its hype.
*Please note that the above chart is only for the period of time spent exercising and doesn't take into account the increase in calories, or or lack thereof of, burnt once the exercise session has been completed.
The reason why training with a higher heart rate burns more fat is because it creates a metabolic disturbance that requires lots of energy to recover from. This is a key point. It is not how many calories or how much fat you burn DURING the session. It is what happens AFTER. All the pathways that are stimulated in order to address the "insult" of excessive demand during the session are sometimes call the "after burn". This includes a host of reactions such as EPOC (Excess Post-exercise Oxygen Consumption) and increases in resting metabolic rate. Yep, it takes a lot of energy to recover from an I.C.E session.
What does training at the prescribed heart rate feel like?
Your 60-70% range is the heart rate number that you can sustain indefinitely (for hours at a time), as in the average number you see when you are out on a day-long hike.
70-80% would be the number you can sustain for roughly 45 minutes;
80-85% would be the number you see when you go hard for about 30 minutes.
I.C.E training would put you into the 85-95% range and equates to short, intense segments, 20 seconds to 3 minutes in duration of hard, all out effort, before your body requires rest or recovery before repeating such effort again.
Anything above 95% would be close to your “max heart rate” and anything below 60% would be for active recovery or rest days.
I don’t know about you but I don’t have the spare time to be fart arseing around in the 60-65% zone. 20-25 mins of kicking the heart rate up to 80-95% and let the fat melt off while I’m doing other things….Bring it ON!!!
If you want to turn an I.C.E 80-95% MHR session into a 60-70%, session go right ahead, it’s your fat you ain’t burning not mine.
P.S The whole heart rate training calculation 220-age and take percentage of MHR isn't something I use nor recommend. ALL 40 year olds are going to have the same training heart rate? I don't think so. I've used the Heart Rate Training Zones as an EXAMPLE of why training at a lower intensity to "burn more fat" is not the best use of your time .
IF it doesn't CHALLENGE you, it doesn't CHANGE YOU.
