I recently got a heart monitor and have been trying to figure out the best ‘zone’ to be in and what not.
My question for you guys is this: To burn fat you’re supposed to be in the ‘aerobic’ zone which for me is
between 118-135. My heart rate gets up to 150 from time and time, but when I’m finished my HRM gives me
an average for the time I’ve spent exercising. If I have an average of 132 for 60 minutes, should I consider
that I burned fat for that 60 minutes or only for the actual time I was at between 118-135?
Thanks alot!
Aranel

Welcome, Aranel. According to Wayne Westcott, PhD, strength advisor to the South Shore (MA) YMCA (as quoted in Prevention magazine), you are always burning fat, even when asleep. The heart rate zone that you are mentioning is a guideline to help you 1) make activity as enjoyable as possible; 2) become aware of your body as a wonder machine of power and energy; and 3) stay motivated to persevere in your chosen activities.

When your heart rate goes into the higher zone, I would need to know your heart rate MAX. For an example, for a heart rate MAX of 168, 90 percent of that is 150 beats per minute. Depending on the individual, activity at 90% or higher may place that individual in a situation of exercising without oxygen (sounds strange, but we’re talking about the muscles working without oxygen). In that 90% or higher situation, the fuel supply is coming strictly from carbohydrates, not from fat. And your muscles won’t enjoy their workout for very long in that state.

Try to remember to consume water during your workout; have some every 15 minutes during a 60 minute session. Maintaining your hydration allows your system to avoid “cardiac drift”. This is the phenomenon of the heart rate climbing as your body becomes overheated. With good hydration, your system’s cooling mechanism functions to allow the heart to operate at a more steady state.

Soooooo, that’s why you are so fortunate to have access to a heart rate monitor; you will enjoy your activity with greater peace of mind ... and you will progress with better control and a higher degree of safety. Sounds to me as though you are off to a great start.

PS Aranel, you might want to have a look at the thread Exercise Experiences / Thoughts from the Gym #4. Some really great ideas on using PRE, perceived rate of exertion, along with your heart rate monitor.

Thanks so much for that info! I am drinking LOTS of water; and I’ll look up that
thread you mentioned.

Aranel

Hi Aranel,

Let me add my voice in welcoming you to MTM.  I can’t really answer your questions, since I’ve got the same ones!  (Yes, that’s right: moderators are just normal people and do not have all the answers.  *grin*) Thanks, Stepper, for providing that information!

Incidentally, the thread Stepper mentioned can be accessed by clicking here. 

Once again, welcome!
Julie

Thanks for the welcome Julie!
I’m glad I’m not the only one who’s lacking understanding on this issue....
I’ve read so much about it and its all very confusing and contradicting.
I’m glad to be able to talk this out with all of you at MTM.

A.

The reason for the various heart rate zones has to do with what your body *primarily* burns for fuel, and often has to do with the length of a workout.  If you’re in that 135bpm range, you can maintain that workout for an hour, and still feel decent afterwards.  If you’re up into the 160-170 range, you’re gonna be far more intense, and won’t be able to maintain the effort as long.

The 135 range is the heart rate at which you burn the highest percentage of fat for fuel. This doesn’t mean you don’t burn anything else, you usually burn a bit of protein (muscle) and carbs too, but as you increase the intensity, you decrease the *percentage* of fuel you get from fat.

However, since your total calories (fat and otherwise) burned increases per time amount as you increase the intensity (heart rate), you may actually burn more fat calories at a lower percentage of total because your total is higher.

For instance. 
You work out for half an hour.  at 135bpm, your total calories burned is 100 calories.  the percentage of fat burned is 50%, so you burned 50 calories of fat. 
However, in the higher cardio range of 150bpm, you would burn more calories, say 150, but only 35% is from fat, but you still burn 52.5 fat calories.
(all numbers are purely for example purposes, and were pulled out my bum, actual numbers would require looking up and I am lazy)

Now, there’s plenty more to this, but that’s the basics.  The longer you stay in the higher heart rate zones, the ratio of fat burned drops, because you don’t get as much oxygen in and therefore aren’t burning as much fat, and eventually if you are at very high heart rates for overly long you go into anaerobic mode, which is what is described above, when you burn carbs instead of fat because your muscles don’t get enough oxygen to use fat.

There is, of course, benefit to training in higher heart rate zones, stronger heart, better lung capacity, etc.  But, the reason people talk about that magic 130-135 number is simply because that is the range of highest percentage of fat burn per time interval.  And you’re not usually dead tired afterward.

For variation I do long slow steady-state cardio, intervals, shorter sessions (30 min and under) of 150s cardio, HIIT, and short sessions of burnout (higher heart rate (170s), till I drop.  kinda fun in a masochistic way, usually done in about 15 minutes).

130 range is fine when one starts out, but it’s best to get in some of the higher heart rate training too, for heart and lung fitness, and because we don’t always have an hour to sit around trying to burn off fat.

Hey Aoife! Thanks for this post. It was most helpful!

Ok, this is starting to make sense.
I am spinning for 60 minutes 3- 4x a week and doing strength/interval training 2-3x a week.
So the spinning days my HR gets up there, the other days it stays in the 124 area.
I also do brief sprints of cardio between the sets to keep my HR up.
Thanks for your help~
A.