Tuesday, August 31, 2010

Heart Rate Zones.

Are HR zones a myth?
Heart rate zones, we've all heard of them, all seen the cardio equipment with  "HR at 50% max burns "x" % of fat" etc. Well I'm here to tell you that this is a myth. The idea of calculating a hear rate zone for "fat burning" for everyone across the board,  is ridiculous as those equations (220-age= Max HR/ 40-60%= fat burning zone) have a plus or minus of 10-15 beats per minute!

A case against HR zone training
Should we even be trying to target fat burning zones? The basis for targeting fat burning zones is based on science from 20 years ago. Basically the theory goes as follows: the lower intensity the exercise the higher percentage of fat you will burn as a major energy source (the higher the intensity, the ratio drops to favouring carbohydrate as a fuel source). One problem with this is our ability to apply reductio ad absurdum to it, meaning we can demonstrate it to be false by taking the idea to an absurd conclusion, as in: "sleeping would be the best form of fat burning exercise", which it may be, but you do not burn enough calories for it to sufficiently tackle fat loss. Another problem with this as stated above, is most people have incorrectly measured their fat burning zone (as the above equation is out of date and inaccurate). Another problem is it doesn't take into account any other factors such as EPOC (Excess Post Exercise Oxygen Consumption) which is basically an oxygen debt that your body has to make up (when doing intense exercise). The way it does this is by raising metabolism (for 24-48hrs post exercise), which means a higher caloric burn at rest! It also doesn't take into account other fat burning process such as catecholamine production and lactic acid production which also raise metabolism. These several example alone should demonstrate the incoherent thought process behind this idea, and the antiquated notion of HR zone training

When you train in a "fat burning zone" you do burn a higher percentage of fat during the session, which is fine, but let's say, as a hypothetical you burn 300 calories in a 1hr steady state session on a x-trainer. Let's assume you burn 170 calories from fat and 130 calories from carbohydrates, that's all well and good, but due to the low intensity nature of the exercise, you haven't raised metabolism at all (some even postulate that steady state, "fat burning" cardio reduces metabolism, hence reducing how many calories you can burn outside the session). The effect is: the calories you burn during the session are all you burn! Now let's say you do a HIIT session, let's suppose you burn 200 calories in a 20 minute session (which is already better), let's say you burn 120 calories of carbohydrates and 80 calories of fat, this is fine for several reasons. (A): you've still burnt 200 calories which at the end of the day is still energy burnt, (B): you've raised your metabolism sufficiently to burn calories (and because you're at rest it will be mostly fat) for the next 24-48hrs and (C): you get less wear and tear on your joints too and have no risk of reducing metabolism through muscle wasting.

Now when training for endurance or for HIIT it's all about getting your HR rate up high, both training modalities require a maximum HR possible while still being able to continue work. The real evidence of health comes from the "bounceback", how fast your HR drops backs down is the indicator of how fit you are, as well as how long you can maintain it at working maximums. Ultimately these training modalities are designed to get you faster and able to go further, in terms of a sport, so training at maximum intensities will develop your energy systems (ATP-PC, lactate and oxygen), the byproduct is weight loss and fitness. I personally think the idea of training at HR rate intensities other than maximum is a residual meme from science 20 years ago. As Michael Boyle states on Interval Training:
"Interval Training Questions
Michael Boyle: "I received an email from a college coach who had watched my Interval Training DVD. After watching, there were still more questions so I figured this might be a better way to answer them.
1. What is the best way to calculate max heartrate.
I think the best way to calculate max heartrate is to not calculate it. When you have athletes you can look at heartrates at the end of some type of maximum effort test. We do a five mile AirDyne test and get our max heartrates from that. Assume that max is 5-10 beats higher than the highest heartrate achieved and you will be safe.
2. What is the best procedure for taking accurate resting HRs.
The best way to get resting heartrates is to ask the athletes to get them first thing in the morning right out of bed. I don't think this is realistic so I just had my guys lay down on the floor with their heartrate monitors on and try to consciously get their heartrates as low as possible. The lowest number achieved was considered to be the resting heartrate.
3. We have had some players who I felt are fit had a hard time getting down to a Hr of 120 or took a really long time. Any advice?
Yes, athletes who have trouble hitting what we are calling the "theoretical 60%" usually have done too much steady work and not enough interval work. Generally these will be athletes who prefer long runs or long rides. They have not been training their heart to recover. The solution for these kids is more interval work. They are not in hockey shape." (Boyle 2010)
I think it's obvious from this very limited review, that HR zone training doesn't stand up to logical muster or on an evidential basis. It almost appears to be some authoritative idea, that if it's on a piece of cardio equipment, it must be right. We can question authority, the status quo, and we can do our own investigations. My brief investigation seems to support my hypothesis. Training either for endurance, fat loss, to raise short burst cardio power, all require intense training, not by heart rates, but with structured programs tailored to the individual, by professionals.

Boyle M., (2010). Interval Training Questions. http://www.strengthcoach.com/members/2187.cfm

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