I do some cardiovascular exercises at the gym on various machines. On most of them I'll see an indicator that shows your heartrate on a scale going from 'Normal >> Fat loss >> Cardio >> Peak" Now most of the time when I do my exercises, I'm in the 'peak' zone, even at around 135-140. So my questions is, WHY is there a 'fat loss' zone. And why would I lose MORE fat with that specific heartrate zone as opposed to the 'peak' zone????

Thanks

the 'zones' are to do with the differing energy systems the body uses at different exercise intensities, or heart-rates.

the 'fat burning zone' will occur at a slightly elevated heart rate because a greater percentage of the calories burned should come from fat. however because of the low intensity work, the TOTAL calories burnt will not be much.

higher intensity work will burn a smaller percentage of fat, but with the total calorie expenditure being a lot higher, the actual fat burnt will work out greater overall...

Personally i would much rather do a quick 20 minute run than spend an hour walking on a treadmill.

Nick

Or even on this forum. This has been talked about time and time again. Just do a search on "fat burning zone".

The "fat loss" zone refers to the heart rate (exercise intensity) in which your primary energy source is fat. In other words, while you're in this zone you're using fat as your energy source instead of carbohydrates. Keep in mind however, that at any given intensity you're actually using more than one energy system.

At higher intensities your primary energy source will come from carbs.

The thing to realize is that just because in the "fat burn" zone fat will be your primary energy source, it doesn't mean that it's a more effective for fat loss. Higher intensity exercise, like interval training, causes a spike in your metabolism after you are finished exercising. The effect? You continue to burn energy (ie. fat) at a higher rate when you're finished exercising than you did before you started the exercise. This spike can last up to 24 hours post exercise.

After looking through the research at the effects of interval training on fat loss as compared to low intensity exercise, you're better off sticking with high intensity intervals.

Keep in mind also that those heart rate zones found on machines are based on max heart rate calculations and not VO2 Max. In other words, they're not very accurate.

Have you seen the big (2006) review on EPOC? If so, I'd love to hear your thoughts.

I'm talking about:

J Sports Sci. 2006 Dec;24(12):1247-64. Links
Effects of exercise intensity and duration on the excess post-exercise oxygen consumption.

* Laforgia J,
* Withers RT,
* Gore CJ.

School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA.

Recovery from a bout of exercise is associated with an elevation in metabolism referred to as the excess post-exercise oxygen consumption (EPOC). A number of investigators in the first half of the last century reported prolonged EPOC durations and that the EPOC was a major component of the thermic effect of activity. It was therefore thought that the EPOC was a major contributor to total daily energy expenditure and hence the maintenance of body mass. Investigations conducted over the last two or three decades have improved the experimental protocols used in the pioneering studies and therefore have more accurately characterized the EPOC. Evidence has accumulated to suggest an exponential relationship between exercise intensity and the magnitude of the EPOC for specific exercise durations. Furthermore, work at exercise intensities >/=50 - 60% O2max stimulate a linear increase in EPOC as exercise duration increases. The existence of these relationships with resistance exercise at this stage remains unclear because of the limited number of studies and problems with quantification of work intensity for this type of exercise. Although the more recent studies do not support the extended EPOC durations reported by some of the pioneering investigators, it is now apparent that a prolonged EPOC (3 - 24 h) may result from an appropriate exercise stimulus (submaximal: >/=50 min at >/=70% O2max; supramaximal: >/=6 min at >/=105% O2max). However, even those studies incorporating exercise stimuli resulting in prolonged EPOC durations have identified that the EPOC comprises only 6 - 15% of the net total oxygen cost of the exercise. But this figure may need to be increased when studies utilizing intermittent work bouts are designed to allow the determination of rest interval EPOCs, which should logically contribute to the EPOC determined following the cessation of the last work bout. Notwithstanding the aforementioned, the earlier research optimism regarding an important role for the EPOC in weight loss is generally unfounded. This is further reinforced by acknowledging that the exercise stimuli required to promote a prolonged EPOC are unlikely to be tolerated by non-athletic individuals. The role of exercise in the maintenance of body mass is therefore predominantly mediated via the cumulative effect of the energy expenditure during the actual exercise.

Been saying this for quite some time.

I think it's interesting and if the only reason I was performing intervals was to increase EPOC, then I might want to reconsider. However, I don't think EPOC is the sole reason interval training is more effective. Rather, it is part of the reason. You also have to consider hormonal responses to the exercise bout and physical adaptations as a result of the exercise. The increased EPOC doesn't tell the whole story, but I'm sure it helps a little.

The only part of that study I really have a problem with is that "non-athletic" individuals can't tolerate that type of stimulus. If by "non-athletic" they mean "untrained", then I'm fine with that. Otherwise, I was unaware that you had to be a gifted athlete to be proficient at riding a stationary bike.

Oh, I wasn't suggesting otherwise. (from the bold)

I just wanted to hear your thoughts.

Trust me, I'm an advocate of HIIT although I think most don't do them with the required intensity, yet think they are doing HIIT.

non-athletic = untrained

I definitely agree that most don't do it with the required intensity. Certainly isn't something a non-motivated person is likely to do on their own.

Thanks for the article though, I hadn't seen it previously.

Anytime.....