i have a question...on every cardio machine there is a "fat burning" and "cardio" range. the fat burning range has a lower heartrate than the cardio range. i believe it's something like 90-120 for fat burning and 140 + for cardio,,,,something like that.

my question is, is there REALLY a difference in goals twixt the two heartrate ranges FOR BURNING FAT? if i want to "fat burn", do i get a better result by keeping my heartrate in the fat burning zone than cardio zone? i ask because i don't really understand why the cardio zone isn't just as good as the "FB" zone for burning fat,,,while i CAN understand why increasing my heartrate is better for cardio.

First off, most of the HR ranges on cardio machines aren't accurate. You should use an HR equation based on your resting HR to figure out your specific target heart rate -- look online, there's plenty of info on this. There's actually a couple of schools of thought on this, but here's the one that makes the most sense to me.

In lower intensity workouts (i.e., lower heart rate), the body is more likely to use fat as a fuel source whereas in higher intensity workouts (think sprints), the body will use other sources for fuel such as sugar. The key point to remember is that just because you're working at higher intensities doesn't mean you aren't burning calories. And in higher intensity workouts, you'll obviously burn more overall calories than at lower intensity settings. Now, you can always get the best of both worlds in your training by doing intervals (low intensity, high intensity, low intensity, high...etc.) over a given timeframe. These have shown to be very effective in burning off calories and fat while ensuring your HR doesn't get out of your target zone for longer than is recommended. It's also a great way to get your body used to working at higher levels and up your overall fitness capacity.

Hope this helps.

I undertand why you might be confused, not a very good set up by the machine.

Obviously the "fat burner" mode is taking the principle that lower intensities burns more fat. This is true relative to the proportions of energy used but is WRONG because absolute fat loss could be higher.

90 120 beats is very low. Absolute fat, or fat useage increases up to a point of around 70-75% max. After that, any increases will mean a lower proportion of fat useage with signicant amount of energy by carbs.

To finish off with an example:

1) Run at around 55% max - you might have around 80% fat use 20% carbs use

2) Run at 70% - you might have around 50% fat use and 50% carb use.

What you need to know, if there was a graph which showed HOW MUCH fat was burnt (not the %), you would see clearly that exercise 2 would burn more fat. Youll also burn more calories which is an added bonus.

Can you expound on this?...and the difference twixt "sugars" and "fat" and their usage? i was reading a post about weight training and aerobics, and a poster said do weights first because that will use up the sugars,,and then follow up with aerobics to burn the fat.

thx

Fat is "harder" to burn than carbohydrate (stored as glycogen). So at low intensities, your body uses mostly fat, while the ratio shifts more to carbohydrate as the intensity increases. However, higher intensity exercise burns more calories, so, up to the anaerobic threshold, it will burn more total fat per minute than lower intensity exercise.

Once past the anaerobic threshold, you can only maintain that intensity for a sprint. That is why doing exercise at sprint intensity is typically done in intervals, interspersed by lower intensity intervals (high intensity interval training or HIIT).

For your cardio exercise, you'll want to find where your anaerobic threshold is, which is usually around 80% of your maximum heart rate. Exercising just below the anaerobic threshold allows you to go long, maximizing distance performance. But note that if you run out of carbohydrates, you won't be able to maintain that intensity and will feel really tired, which is sometimes called the bonk. That is why athletes may carbo-load just before an endurance event, although that is unlikely to be an issue for less than an hour of continuous exercise (unless you eat a low carbohydrate diet).

Knowing your anaerobic threshold, you can also know how hard to make your sprint intervals (as hard as you can above your anaerobic threshold) and lower intensity intervals (below your anaerobic threshold) when doing HIIT.

The two primary sources of energy your body burns for exercise are fat & sugars (i.e glucose / glycogen ). You can't burn fat without oxygen. But, you can burn sugars either with or without oxygen.

In simple terms, aerobic means ' with oxygen ' and anaerobic means ' without oxygen '. The harder you exercise ( i.e your ' intensity ' goes up ) and the more winded you get ( i.e the less oxygen you get ) the greater your body has to rely on anaerobic energy.

Generally speaking, weight training is considered to be primarily an ' anaerobic ' form of exercise - and therefore, although weight training burns both fat and sugars, it generally relies more on sugars for energy than fat. In the same way, although ' aerobic ' cardio burns both fat and sugars, it typically relies more on fat for energy than sugars.

Remember, when you exercise, you burn fat, sugars - and to a lesser extent - protein ...........all at the same time. It is the intensity of your exercise ( i.e. ' aerobic ' vs. ' anaerobic ' ) which will determine the proportion to which your body has to rely on each of these 3 for energy.

I wouldnt include protein as a source of energy, unless your diet isnt up to scratch or long duration training.

Your not really getting less oxygen when training at intensity, just that the oxygen cant keep up with the bodies needs, its to slow.

Actually, protein is a small ( relatively speaking ) source of energy that your body uses during exercise - it's simply a rather insignificant source ( under normal circumstances ) compared to that of fat and sugars. Which why I said " primary sources of energy your body burns for exercise are fat & sugars (i.e glucose / glycogen ) ".

Correct.

You're getting less oxygen than what's required to " keep up with the bodies needs ", so I should have said " the less oxygen you get....to meet your needs )

Yeah i know you know just that because its so small and insignificant i would bother mentioning it (bar a few exceptions of course). I just thought that "a lesser extent" wouldnt be the best word because it could be interpreted anywhere on the spectrum below glucose.

Fair enough.