new Polar F6 heart rate monitor questions?

Just a quick note about "staying in the fat burning zone." (FBZ)

Don't be tricked into thinking that this zone is "better." Yes, it burns a higher PERCENTAGE of fat but (and just making up #s here for the example), say you burn 500 calories in the FBZ and 50% are fat calories. You have burned 250 fat calories.

Now say you do the same work out in the cardio zone and burn 800 calories but only 35% of them are fat. That's stilll 280 calories of fat and more calories overall.

Don't get stuck on the idea of a higher percentage of fat because a low % of a big # is higher than a high % of a low number!

There are other points too such as building more muscle in the cardio zone (I think?) and thus on a day to day basis burning more fat even at resting because of having more muscle... I think the fat zone thing is kind of a myth... I just would not work out UNDER your target zone and eat accordingly either way

so can i just put in that i burned 223 calories in my exercise section?

Yes, but you might want to deduct your BMR calories from it. (If you normally would burn 100 calories per hour in daily activity, and exercise and burn 500 in an hour, you actually burned 400 additional calories.)

I mix my cardio up. I do intervals (alternating between 85% max and 65% max) on some days, and then on other days, I do "endurance" cardio, staying between 65-75% of my max). This is per the advice of a trainer at my gym, in order to get the best "bang for my cardio time."

( I LOVE my HRM! )

You'd deduct them because you didn't magically add time to your day.

For example, from 4-5 pm, I could sit on the sofa and burn an hour's worth of bmr calories. (to keep the math tidy, let's say that's 100 calories an hour)

Or, I could go to the gym and burn those same BMR calories + extra calories through exercise. (so, if I burned 500 total, I actually burned 400 extra). If I eat 500 extra calories, I've actually over-eaten by 100 calories.

To figure out your BMR per hour calories (slightly non-scientifically, as I think you burn less while you're sleeping) just take your BMR and divide it by 24.

Endurance zone is 65%-75%
and interval zone could go from anywhere to 75%-85% in short bursts, with periods of active recovery. So, you could walk on a treadmill, jog on a treadmill to get your HR up to 80% for 30 seconds, then walk again until it falls back to 70% and repeat. I love this kind of workout, because it almost becomes a game, and doesn't get boring. Endurance training is boring (autopilot at not a fast pace) in order to really build cardiovascular strength, you should do both. It also serves to "confuse" your body and you get a more efficient calorie burn for every workout. (at least that's what my trainer taught me)
:flowerforyou:

Thanks viv .. that answered some question i had

see i got my new F4 yesterday .. i wore it to the gym,, i did 20 min on the elleptical for 175 cal .. i keep my HR at about 70%... but then i went to a body attack class and fallowing the teacher my HR was nearly always near 80-85%... and i was wondering if i should slow myself down and not do as much to lower my heart rate.. but now i understand its actualy good to take my heart rate that high ..

but is it ok to keep it up there for like 30 min to 1 h ??

also... what do you keep your target zone at on your HRM ?... i setted mine for 65 to 75 %.. should i set it for 80% instead ?

Thanks for your help !
may

Ok, let me take a crack at answering this. I don't deduct my BMR calories and here's why--I have a relatively sedentary job, so I set my daily activity level for sedentary. So, when I exercise, I count all of them, as I don't have my activity level set high enough to account for a large RMR--which is what we're really considering here. I forget what the R stands for but it's basically your BMR plus your activity level. You can see what MFP has for your RMR by looking on your "Goals' page and looking on the right hand top column.

Now, as for what level of heart rate to work out at, it does make a different. I've been conversing with songbyrdsweet, who is in her final year of obtaining a college degree in studying this kind of stuff, about all this RMR, HR zones, glycogen, and the benefits/no-benefits of weight training.

anyway, I've cut and pasted below what songbyrdsweet posted the other day about HR zones. It really helped me.

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Our bodies will utilize anything for energy. We sort of eat ourselves alive, really. Muscle turnover is constant--even if we aren't training, without sufficient calories, we'll need amino acids. When they can be replaced, they are. We do use a great % of fat for energy while resting (~60%), but the rest comes from glucose. That glucose can come from carbohydrates in the diet, glycerol from triglycerides, or some amino acids. Our blood calcium concentration must stay constant, so if it falls and we don't have dietary calcium available, we even have a hormone that will break down our own bones to increase our blood calcium level. Although we never technically reach homeostasis, our bodies will tear themselves down in an attempt to do so. Nothing is really 'preferred'--our bodies will use whatever is available to produce energy.

Working at higher intensities (>85% MHR) will result in a shorter exercise time due to the oxygen debt and lactic acid build up; even marathoners won't maintain a HR higher than that during a race. This type of activity utilizes a great deal of glucose. If you're not depleted, that doesn't matter, and in the end, your caloric deficit will mostly come from fat while you're resting. If you're glycogen-depleted due to fasting or a no/low-carb diet, you'll use some different ways to produce energy (and won't last very long), and it does pose a higher risk of muscle loss (you'll make glucose out of it).

I think working at moderate intensities (75-85% MHR) is really hitting the spot. This can be maintained for a longer period of time, and while you'll still be using a majority of glucose for energy, some fat can be utilized since you're in an aerobic environment. If you can hang out at 75% MHR for an hour, which is definitely doable for a jog, you'll be burning about 30% of calories from fat. Since you'll be burning a lot of calories here from a higher HR, that 30% of fat will be a good deal of calories.

Lower intensities (65-75% MHR) will burn a greater % of calories from fat, but not as many total calories as 75-85%, and still a majority of energy will come from carbohydrates unless you're doing for 90+ minutes. Here you might be looking at a 40-60 split and you'll still get CV benefits.

Under 65%, you'll be burning the greatest % of fat calories, but the lowest number of calories, and you won't be reaping the CV benefits. This would be better for someone with an injury or who couldn't withstand higher intensities.

With any of these methods, what you use during exercise is pretty much a spit in the bucket compared to the rest of your day; your caloric deficit will be filled using mostly fat. However, aerobic exercise does cause the release of cortisol, a stress-related hormone that breaks down muscle mass. It's harder to hold onto if you're in a deficit and doing a lot of CV work; that's just an unfortunate side effect of being active. Aerobic work impedes anaerobic performance (lifting).

If you're eating enough, only about 10% of your total lbs lost will come from muscle, which won't really be noticeable when spread out over the body. You may only notice something like 1/4 of an inch lost. But if you're following a VLCD for an extended period of time, you're looking at a far greater % of muscle and bone loss. So it's easy to prevent more than a small amount of LBM loss by just eating enough. smile