Re: Is heart rate a good measure of fat burning? - Triathlon Week

09-03-2007, 12:56 AM

I think the reason for the confusion on the fat burning issue is due to a
fundamental misunderstanding. For some time now we have been told that our
muscles burn fat a lower aerobic rates. As our pace increases our bodies
turn to carbs as a quick supplement to meet the growing demand. Therefore,
as a percentage, the amount of fat we are burning goes down, though we are
burning every bit as much as we would at a slower pace.

I use a Polar heart rate monitor and it dutifully tells me that below 70%
max I am burning approximately 60% fat. As I go above 70% max, the
percentage falls to 55% and if I press hard enough will go even lower than
that. However, this does not mean that the extra effort does not have other
benefits that more than compensate for the reduction in percent of fat
burning.

Recent studies have shown that workouts in the higher ranges, say 70 to 90%
of max, raise your metabolism higher and keep it there much longer. That
means that the fat burning machine is running long after the workout is
finished, as much as eighteen hours longer.

Most of us have learned that too much time in the high percentages can build
a cumulative fatigue that can lead to discouragement and often even a
cessation of workouts. The trick then, is to find a balance between aerobic
and anaerobic workouts. Clearly, the bulk of your workouts should be in the
aerobic zones without ignoring the benefits of working in some anaerobic
time for the added benefits.

--
LEE REED
"wizzywiz" <[Only registered and activated users can see links. ]> wrote in message
news:1165764900.814008.216520@l12g2000cwl.googlegr oups.com...
> Hello, there seems to be little consensus on which exercises burn how
> much fat. So, can I just measure the intensity of my calorie burning by
> monitoring my heart rate?
>
> Thanks....
>

09-03-2007, 12:56 AM

On 2007-03-14 13:27:50 +0000, "L W REED" <[Only registered and activated users can see links. ]> said:

> I think the reason for the confusion on the fat burning issue is due to a
> fundamental misunderstanding. For some time now we have been told that our
> muscles burn fat a lower aerobic rates. As our pace increases our bodies
> turn to carbs as a quick supplement to meet the growing demand. Therefore,
> as a percentage, the amount of fat we are burning goes down, though we are
> burning every bit as much as we would at a slower pace.
>
> I use a Polar heart rate monitor and it dutifully tells me that below 70%
> max I am burning approximately 60% fat. As I go above 70% max, the
> percentage falls to 55% and if I press hard enough will go even lower than
> that. However, this does not mean that the extra effort does not have other
> benefits that more than compensate for the reduction in percent of fat
> burning.
>
> Recent studies have shown that workouts in the higher ranges, say 70 to 90%
> of max, raise your metabolism higher and keep it there much longer. That
> means that the fat burning machine is running long after the workout is
> finished, as much as eighteen hours longer.
>
> Most of us have learned that too much time in the high percentages can build
> a cumulative fatigue that can lead to discouragement and often even a
> cessation of workouts. The trick then, is to find a balance between aerobic
> and anaerobic workouts. Clearly, the bulk of your workouts should be in the
> aerobic zones without ignoring the benefits of working in some anaerobic
> time for the added benefits.

What actually happens is that when the heart rate gets above 60-70% the max for
your age and weight, your body starts to convert proteins from your
muscle tissue
into energy, if you keep it the 60-70% range then your body is able to
burn fat instead.
--
Three wheels good, two wheels ok

[Only registered and activated users can see links. ]

09-03-2007, 12:56 AM

Buck wrote:
> What actually happens is that when the heart rate gets above 60-70% the
> max for
> your age and weight, your body starts to convert proteins from your
> muscle tissue
> into energy, if you keep it the 60-70% range then your body is able to
> burn fat instead.

Can you provide a source for that claim? It's a very different
mechanism to that described by anyone else I've ever talked to: the
"conventional wisdom", as it were, claims that high-intensity workouts
are fuelled by glycogen which is stored in muscles and in the liver.
Not by protein.

-dan

--
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09-03-2007, 12:56 AM

Daniel Barlow wrote:
:: Buck wrote:
::: What actually happens is that when the heart rate gets above 60-70%
::: the max for
::: your age and weight, your body starts to convert proteins from your
::: muscle tissue
::: into energy, if you keep it the 60-70% range then your body is able
::: to burn fat instead.
::
:: Can you provide a source for that claim? It's a very different
:: mechanism to that described by anyone else I've ever talked to: the
:: "conventional wisdom", as it were, claims that high-intensity
:: workouts are fuelled by glycogen which is stored in muscles and in
:: the liver. Not by protein.

Once you deplete gylcogen your body will probably start converting protein,
if you can still move by then, that is.

09-03-2007, 12:56 AM

Roger Zoul wrote:
> Daniel Barlow wrote:
> :: Buck wrote:
> ::: What actually happens is that when the heart rate gets above 60-70%
> ::: the max for
> ::: your age and weight, your body starts to convert proteins from your
> ::: muscle tissue
> ::: into energy, if you keep it the 60-70% range then your body is able
> ::: to burn fat instead.
> ::
> :: Can you provide a source for that claim? It's a very different
> :: mechanism to that described by anyone else I've ever talked to: the
> :: "conventional wisdom", as it were, claims that high-intensity
> :: workouts are fuelled by glycogen which is stored in muscles and in
> :: the liver. Not by protein.
>
> Once you deplete gylcogen your body will probably start converting protein,
> if you can still move by then, that is.
>
>
This may apply to long term riding over an hour as some sort of an
average, but sometimes I just go out and do a 2 block sprint to get my
heart rate up to 80-90% for a few minutes. These are the days when
riding is just out for one reason or another. I walk back home and by
then my heart rate has settled down but my metabolism seems to stay up
there for about a half an hour. I don't jog, never have and never will,
but I do run above jogging speed and land as intended on the balls of my
feet. Landing on my heels while jogging a mile or 2 is not in my plans.
Riding a 100 miles in a day is in my plans for the summer.
Heart rate versus calories depends on how good of shape the individuals
heart is, how much they weigh, and how long they do it. I don't think my
sprints are good for more than 100 calories but my 100 mile rides burn a
lot whether I ride fast or slow.
Think duration.
Bill Baka

09-03-2007, 12:56 AM

On 2007-03-14 14:57:44 +0000, Daniel Barlow <[Only registered and activated users can see links. ]> said:

> Buck wrote:
>> What actually happens is that when the heart rate gets above 60-70% the
>> max for
>> your age and weight, your body starts to convert proteins from your
>> muscle tissue
>> into energy, if you keep it the 60-70% range then your body is able to
>> burn fat instead.
>
> Can you provide a source for that claim? It's a very different
> mechanism to that described by anyone else I've ever talked to: the
> "conventional wisdom", as it were, claims that high-intensity workouts
> are fuelled by glycogen which is stored in muscles and in the liver.
> Not by protein.
>
>
> -dan

That's what I meant, I know that training for long periods like that
ultimately damages muscle, 30 minutes to an hour can be good
for the heart though, the fat burnt at 60-70% is the excess fat but at higher
levels glycogen is burnt off, I understand that glycogen is a starch
held in liquid
state to fuel the muscles etc during normal use.
--
Three wheels good, two wheels ok

[Only registered and activated users can see links. ]

09-03-2007, 12:56 AM

Buck wrote:
> That's what I meant, I know that training for long periods like that
> ultimately damages muscle, 30 minutes to an hour can be good

AFAIUI (but I'm betting the triathletes have a better grasp of the
issues than I do) even if you exercise to "exhaustion" you are unlikely
to completely exhaust your muscle glycogen: fatigue is your body's way
of telling you to back off.

[Only registered and activated users can see links. ]
[Only registered and activated users can see links. ]

-dan

--
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09-03-2007, 12:56 AM

Buck wrote:
> On 2007-03-14 13:27:50 +0000, "L W REED" <[Only registered and activated users can see links. ]> said:
>
>> I think the reason for the confusion on the fat burning issue is due to a
>> fundamental misunderstanding. For some time now we have been told that
>> our
>> muscles burn fat a lower aerobic rates. As our pace increases our bodies
>> turn to carbs as a quick supplement to meet the growing demand.
>> Therefore,
>> as a percentage, the amount of fat we are burning goes down, though we
>> are
>> burning every bit as much as we would at a slower pace.
>>
>> I use a Polar heart rate monitor and it dutifully tells me that below 70%
>> max I am burning approximately 60% fat. As I go above 70% max, the
>> percentage falls to 55% and if I press hard enough will go even lower
>> than
>> that. However, this does not mean that the extra effort does not have
>> other
>> benefits that more than compensate for the reduction in percent of fat
>> burning.
>>
>> Recent studies have shown that workouts in the higher ranges, say 70
>> to 90%
>> of max, raise your metabolism higher and keep it there much longer. That
>> means that the fat burning machine is running long after the workout is
>> finished, as much as eighteen hours longer.
>>
>> Most of us have learned that too much time in the high percentages can
>> build
>> a cumulative fatigue that can lead to discouragement and often even a
>> cessation of workouts. The trick then, is to find a balance between
>> aerobic
>> and anaerobic workouts. Clearly, the bulk of your workouts should be
>> in the
>> aerobic zones without ignoring the benefits of working in some anaerobic
>> time for the added benefits.
>
> What actually happens is that when the heart rate gets above 60-70% the
> max for
> your age and weight, your body starts to convert proteins from your
> muscle tissue
> into energy, if you keep it the 60-70% range then your body is able to
> burn fat instead.

I believe Chris Carmichael states in his book "Food for Fitness":
the percentage of fat that you burn may go down as your heart rate goes
up, but you are still burning a lot of fat if not the same amount at the
higher heart rates (per calorie). The percentage of carbohydrates goes
up as your heart rate increases, which is why you take gels and bars so
that you can continue to burn the carbohydrates and continue to burn the
fat stores.

09-03-2007, 12:56 AM

Daniel Barlow wrote:
:: Buck wrote:
::: That's what I meant, I know that training for long periods like that
::: ultimately damages muscle, 30 minutes to an hour can be good
::
:: AFAIUI (but I'm betting the triathletes have a better grasp of the
:: issues than I do) even if you exercise to "exhaustion" you are
:: unlikely to completely exhaust your muscle glycogen: fatigue is your
:: body's way of telling you to back off.
::
:: [Only registered and activated users can see links. ]
:: [Only registered and activated users can see links. ]
::

Certainly you won't completely exhaust it, because your body will break down
muscle tissue to produce more (in the absence of dietary carbs). However,
you can deplete glycogen to the point of being unable to continue exercise
(ie, bonking).