exercise physiology question

Hey all, a question for anyone out there with an exercise physiology
background.

My wife has recently embarked on a weight loss/exercise plan at "Curves"
here in our home town. The gals running the place tell her to keep her
heart rate below 132 beats per minute when exercising or "she'll be burning
muscle instead of fat."

From what i know of exercise physiology this is not true. When exercising
we all burn glycogen stores aerobically (if the heart rate is below
150-160ish) or anaerobically (if the heart rate is very high) or fat (if the
heart rate is very low - say approximately below 120ish). There would never
be a situation where a normal person exercising in normal heart ranges
eating a normal diet would burn MUSCLE as a fuel.

I told her she can get her heart rate up to 140-150-160-170 or anywhere in
between and she'll still be burning up fat stores indirectly - NOT muscle.
The way i learned it is that we all burn up stored glycogen first and then
use food to replace it. If we are calorie deficient for food intake then
she uses her fat stores to replace the glycogen...

am I right or am I wrong ??

JKal.

Jeff and Stephanie Kalember wrote:
Hey all, a question for anyone out there with an exercise physiology
background.

My wife has recently embarked on a weight loss/exercise plan at "Curves"
here in our home town. The gals running the place tell her to keep her
heart rate below 132 beats per minute when exercising or "she'll be burning
muscle instead of fat."

Huh????

From what i know of exercise physiology this is not true. When exercising
we all burn glycogen stores aerobically (if the heart rate is below
150-160ish) or anaerobically (if the heart rate is very high) or fat (if the
heart rate is very low - say approximately below 120ish). There would never
be a situation where a normal person exercising in normal heart ranges
eating a normal diet would burn MUSCLE as a fuel.

I told her she can get her heart rate up to 140-150-160-170 or anywhere in
between and she'll still be burning up fat stores indirectly - NOT muscle.
The way i learned it is that we all burn up stored glycogen first and then
use food to replace it. If we are calorie deficient for food intake then
she uses her fat stores to replace the glycogen...

am I right or am I wrong ??

You are absolutely right, the only way you can burn fat directly, is by
doing continuous low/mid-level exercise over very long periods, i.e.
like a multi-day Easter xc ski trip across Hardangervidda in Norway.

For people who are used to training multiple times/week, it seems to
take several days of strenuous longterm activity to teach the body to
use fat directly, I know that in all the years when we did the 4-day xc
ski from north to south in Telemark, it was on the third or even fourth
day that I got used to that kind of activity, and didn't need to fill up
the stores with food&drink every hour or two.

You should suggest something like the Canadian 160 km two-day event as a
surefire way to drop a few pounds! (Not so much during the two ski days,
as during the previous months/years of skiing needed to get in shape to
complete the challenge! :-)

There are other great benefits as well, last year I think someone posted
a link here to a Swedish medical research group who have been monitoring
all Swedish citizens who had completed Vasaloppet at least once during a
ten-year period:

Simply going through the training needed to do this was sufficient to
greatly reduce the risk of just not cardiac problems, but also many
other deceases, including cancer (and yes, they corrected their numbers
for smoking/non-smoking as well.)

.... googling..

Yes, here it is:

"Mortality amongst participants in Vasaloppet: a classical
long-distance ski race in Sweden"

http://www.blackwell-synergy.com/doi....x?cookieSet=1

This was a study of 49219 men and 24403 women, over ten years of Vasa
starts, and they found death risks reduced by 50% for all
participants/illnesses, with significant reductions across all major
causes of death, even including injuries and poisoning! :-)

With benefits like these, who cares that she'll lose those pounds as well?

Terje
--
-
"almost all programming can be viewed as an exercise in caching"

On Mar 22, 8:48*am, "Jeff and Stephanie Kalember"
wrote:
Hey all, a question for anyone out there with an exercise physiology
background.

My wife has recently embarked on a weight loss/exercise plan at "Curves"
here in our home town. *The gals running the place tell her to keep her
heart rate below 132 beats per minute when exercising or "she'll be burning
muscle instead of fat."

From what i know of exercise physiology this is not true. *When exercising
we all burn glycogen stores aerobically (if the heart rate is below
150-160ish) or anaerobically (if the heart rate is very high) or fat (if the
heart rate is very low - say approximately below 120ish). *There would never
be a situation where a normal person exercising in normal heart ranges
eating a normal diet would burn MUSCLE as a fuel.

I told her she can get her heart rate up to 140-150-160-170 or anywhere in
between and she'll still be burning up fat stores indirectly - NOT muscle.
The way i learned it is that we all burn up stored glycogen first and then
use food to replace it. *If we are calorie deficient for food intake then
she uses her fat stores to replace the glycogen...

am I right or am I wrong ??

JKal.

Hi,

First, are you saying that your wife's aerobic threshold is 150 to
160 bpm? What's her maximum heart rate?

My first edition Rob Sleamaker "Serious Training for Serious Athletes"
considers a "Zone One" training intensity to be the overdistance (long
slow distance) training level that improves or stimulates free fatty
acid mobilization amongst other physicogical benefits. Sleamaker
defines this level to generally be 55 to 65% of VO2max or 60 to 70% of
max heart rate. Of course lactate levels would be a better measure.


That said, the Curves people must be confusing carbohydrates/glycogen
and muscle at a training rate over 132 bpm. The sequence of energy
use is glycogen (carbohydrates), fatty acids, then muscle. But muscle
loss is pretty extereme. Think floating in a life boat for several
weeks.

Edgar

On Sat, 22 Mar 2008 11:48:59 -0400, "Jeff and Stephanie Kalember"
wrote:

Hey all, a question for anyone out there with an exercise physiology
background.

My wife has recently embarked on a weight loss/exercise plan at "Curves"
here in our home town. The gals running the place tell her to keep her
heart rate below 132 beats per minute when exercising or "she'll be burning
muscle instead of fat."

That's a variant of an exercise myth based on a misunderstanding of
physiology. As one person told me, if you are burning fat at low
intensity workouts, you must be burning muscle at high intesity. He
did not comprehend a difference between fats in molecular form as a
fuel source and fat as a cellular mass.

I didn't ask him what he expected to grow if he planted birdseed. I
should have, the answer probably would have been entertaining.




From what i know of exercise physiology this is not true. When exercising
we all burn glycogen stores aerobically (if the heart rate is below
150-160ish) or anaerobically (if the heart rate is very high) or fat (if the
heart rate is very low - say approximately below 120ish). There would never
be a situation where a normal person exercising in normal heart ranges
eating a normal diet would burn MUSCLE as a fuel.

I told her she can get her heart rate up to 140-150-160-170 or anywhere in
between and she'll still be burning up fat stores indirectly - NOT muscle.
The way i learned it is that we all burn up stored glycogen first and then
use food to replace it. If we are calorie deficient for food intake then
she uses her fat stores to replace the glycogen...

am I right or am I wrong ??

JKal.

On Mar 22, 11:02*pm, wrote:
On Mar 22, 8:48*am, "Jeff and Stephanie Kalember"





wrote:
Hey all, a question for anyone out there with an exercise physiology
background.

My wife has recently embarked on a weight loss/exercise plan at "Curves"
here in our home town. *The gals running the place tell her to keep her
heart rate below 132 beats per minute when exercising or "she'll be burning
muscle instead of fat."

From what i know of exercise physiology this is not true. *When exercising
we all burn glycogen stores aerobically (if the heart rate is below
150-160ish) or anaerobically (if the heart rate is very high) or fat (if the
heart rate is very low - say approximately below 120ish). *There would never
be a situation where a normal person exercising in normal heart ranges
eating a normal diet would burn MUSCLE as a fuel.

I told her she can get her heart rate up to 140-150-160-170 or anywhere in
between and she'll still be burning up fat stores indirectly - NOT muscle.
The way i learned it is that we all burn up stored glycogen first and then
use food to replace it. *If we are calorie deficient for food intake then
she uses her fat stores to replace the glycogen...

am I right or am I wrong ??

JKal.

Hi,

First, are you saying that your wife's aerobic threshold *is 150 to
160 bpm? *What's her maximum heart rate?

My first edition Rob Sleamaker "Serious Training for Serious Athletes"
considers a "Zone One" training intensity to be the overdistance (long
slow distance) training level that improves or stimulates free fatty
acid mobilization amongst other physicogical benefits. *Sleamaker
defines this level to generally be 55 to 65% of VO2max or 60 to 70% of
max heart rate. *Of course lactate levels would be a better measure.

That said, the Curves people must be confusing carbohydrates/glycogen
and muscle at a training rate over 132 bpm. *The sequence of energy
use is glycogen (carbohydrates), fatty acids, then muscle. *But muscle
loss is pretty extereme. *Think floating in a life boat for several
weeks.

Edgar- Hide quoted text -

- Show quoted text -


Yes, Edgar, I'd estimate her aerobic threshold to be about 150ish.
Being close to 40 yrs old I'd say her approximate max hr is around
180ish.
JKal.

On Mar 23, 5:49*pm, 32 Degrees B wrote:
On Mar 22, 11:02*pm, wrote:





On Mar 22, 8:48*am, "Jeff and Stephanie Kalember"

wrote:
Hey all, a question for anyone out there with an exercise physiology
background.

My wife has recently embarked on a weight loss/exercise plan at "Curves"
here in our home town. *The gals running the place tell her to keep her
heart rate below 132 beats per minute when exercising or "she'll be burning
muscle instead of fat."

From what i know of exercise physiology this is not true. *When exercising
we all burn glycogen stores aerobically (if the heart rate is below
150-160ish) or anaerobically (if the heart rate is very high) or fat (if the
heart rate is very low - say approximately below 120ish). *There would never
be a situation where a normal person exercising in normal heart ranges
eating a normal diet would burn MUSCLE as a fuel.

I told her she can get her heart rate up to 140-150-160-170 or anywhere in
between and she'll still be burning up fat stores indirectly - NOT muscle.
The way i learned it is that we all burn up stored glycogen first and then
use food to replace it. *If we are calorie deficient for food intake then
she uses her fat stores to replace the glycogen...

am I right or am I wrong ??

JKal.

Hi,

First, are you saying that your wife's aerobic threshold *is 150 to
160 bpm? *What's her maximum heart rate?

My first edition Rob Sleamaker "Serious Training for Serious Athletes"
considers a "Zone One" training intensity to be the overdistance (long
slow distance) training level that improves or stimulates free fatty
acid mobilization amongst other physicogical benefits. *Sleamaker
defines this level to generally be 55 to 65% of VO2max or 60 to 70% of
max heart rate. *Of course lactate levels would be a better measure.

That said, the Curves people must be confusing carbohydrates/glycogen
and muscle at a training rate over 132 bpm. *The sequence of energy
use is glycogen (carbohydrates), fatty acids, then muscle. *But muscle
loss is pretty extereme. *Think floating in a life boat for several
weeks.

Edgar- Hide quoted text -

- Show quoted text -

Yes, Edgar, I'd estimate her aerobic threshold to be about 150ish.
Being close to 40 yrs old I'd say her approximate max hr is around
180ish.
JKal.- Hide quoted text -

- Show quoted text -

At 150 to 160 bpm for a 180 bpm max heart rate, she will be working in
the just sub-anerobic range. She would not be burning muscle as
Curves told her, but she would be burning a higher proportion of
glycogen (carbs) than fat. That said, she will be burning a lot more
calories than working at a Level 1 heart rate range.

My guess is that Curves is suggesting that she work out at a Level 1
range (70% max heart rate) because she will be able to work at the
under 132 bpm work load for a lot longer time than just sub-lactic
acid threshold. She would burn a lot more fat putting in a hour plus
at 132 bpm compared to a 10 min sub-threshold interval then feeling so
worn out that she doesn't work out the next day.

The sub-threshold workout should be added after developing a solid
base in combination with a bose of overdistance work.

Edgar

32 Degrees B wrote:
Yes, Edgar, I'd estimate her aerobic threshold to be about 150ish.
Being close to 40 yrs old I'd say her approximate max hr is around
180ish.

I assume she's never done any long-term serious sports then?

It is quite interesting to note that the world cup skiers seems capable
of ~90% of max for long periods, and I know that orienteers can sustain
92-92% of max as the average over an hour.

That would be about 165 bpm.

Terje
--
-
"almost all programming can be viewed as an exercise in caching"

On Sun, 23 Mar 2008 21:13:59 -0700 (PDT), wrote:



At 150 to 160 bpm for a 180 bpm max heart rate, she will be working in
the just sub-anerobic range. She would not be burning muscle as
Curves told her, but she would be burning a higher proportion of
glycogen (carbs) than fat. That said, she will be burning a lot more
calories than working at a Level 1 heart rate range.

My guess is that Curves is suggesting that she work out at a Level 1
range (70% max heart rate) because she will be able to work at the
under 132 bpm work load for a lot longer time than just sub-lactic
acid threshold. She would burn a lot more fat putting in a hour plus
at 132 bpm compared to a 10 min sub-threshold interval then feeling so
worn out that she doesn't work out the next day.


Yeah, she should work out at the highest intensity that she can do the
full time allotted and isn't too blown out (mentally or physically) to
do it again and again over time.

Jeff and Stephanie Kalember wrote:
Hey all, a question for anyone out there with an exercise physiology
background.

My wife has recently embarked on a weight loss/exercise plan at "Curves"
here in our home town. The gals running the place tell her to keep her
heart rate below 132 beats per minute when exercising or "she'll be burning
muscle instead of fat."

Sounds like a confused employee at Curves.

At rest and at low work rates muscle "prefers" to utilise free fatty
acids as the primary fuel, but beta-oxidation of lipids is too slow to
provide enough acetyl-CoA at moderate to high work rates.

At moderate work rates glucose (from plasma, or broken down from
glycogen stores) is converted to pyruvate. If there's enough oxygen
being delivered to the tissues the pyruvate enters the TCA cycle and is
metabolised aerobically. If oxygen is not available, the pyruvate is
reduced to lactate anaerobically, producing much less energy per glucose
molecule, and contributing to lactic acid accumulation.

At extremely high work rates, the production of lactate becomes a
limiting factor, as despite rapid transport into the bloodstream, local
accumulation overwhelms available buffering systems and the local pH
drops enough to inhibit functionally important enzymes, leading to
cramping/tetany/exhaustion/etc.

The relationship of type of fuel being used to heart rate exists only
insofar as one can equate the heart rate to the workload demand on the
muscle tissue. The two are positively correlated, however the
relationship is neither linear, nor the same across different
individuals. One's theoretical maximum heart rate is largely a function
of age (and co-morbidities), and so setting benchmarks of 50%, 70%, 90%
of maximum heart rate has little meaning in terms of aerobic vs
anaerobic performance of muscle tissue unless you're dealing with a very
homogeneous population (say, a bunch of similarly highly trained elite
athletes of the same age).

A 50 year old masters world cup skiier who consistently kicks ass in his
age group has something _very_ different going on in his muscles when he
is exercising at 80% of his maximal heart rate, than does a 50 year old
couch potato at the same % heart rate.

Trained athletes deliver more oxygen to their muscles per unit time, and
there are adaptations that result in the more efficient utilisation of
fatty acids, which leaves them able to maintain a higher level of
exertion before having to switch to anaerobic metabolic pathways, and
thus incur a lesser oxygen debt for the same workload.

In terms of what your wife should be doing... She should aim for a work
rate that she can maintain for a reasonably prolonged length of time. If
she becomes profoundly exhausted very quickly, she's going too hard. If
she can sit/stand there all day, she's not going hard enough. Once she's
worked out which is which, taking note of her plateau heart rate during
those differing workloads will provide useful benchmarks for future
training. Arbitrarily assigning heart rates to represent assumed
workload and extrapolating that to infer fuel source changeover points
prior to setting foot/bum on a trail or piece of exercise equipment is
almost as accurate and reliable an approach as consulting an astrologer.

Oh and unless she's starving herself to death, she won't be "burning
muscle" anytime soon.

Thus endeth the rant... Sorry... hope some of it was a least vaguely
helpful? :-)

Cheers,
Chris

Now that is an exercise physiologists' answer !!!!!!!!! Dang !!! Its been 20
years since my Ex. Phys. class in college (Dr. Watts, NMU !!)

Its funny that EVERY SINGLE adult my wife asked at work agreed that she was
"burning muscle" if she exercised too hard.
And, every single skier on here and that i know (and asked) said NO WAY !!

Personally I think the "CURVES" people tell their customers this to keep
them at low intensity so its safe, easier, and you enjoy the workout more.

JKal.


"Chris Cole" wrote in message
...
Jeff and Stephanie Kalember wrote:
Hey all, a question for anyone out there with an exercise physiology
background.

My wife has recently embarked on a weight loss/exercise plan at "Curves"
here in our home town. The gals running the place tell her to keep her
heart rate below 132 beats per minute when exercising or "she'll be
burning muscle instead of fat."

Sounds like a confused employee at Curves.

At rest and at low work rates muscle "prefers" to utilise free fatty acids
as the primary fuel, but beta-oxidation of lipids is too slow to provide
enough acetyl-CoA at moderate to high work rates.

At moderate work rates glucose (from plasma, or broken down from glycogen
stores) is converted to pyruvate. If there's enough oxygen being delivered
to the tissues the pyruvate enters the TCA cycle and is metabolised
aerobically. If oxygen is not available, the pyruvate is reduced to
lactate anaerobically, producing much less energy per glucose molecule,
and contributing to lactic acid accumulation.

At extremely high work rates, the production of lactate becomes a limiting
factor, as despite rapid transport into the bloodstream, local
accumulation overwhelms available buffering systems and the local pH drops
enough to inhibit functionally important enzymes, leading to
cramping/tetany/exhaustion/etc.

The relationship of type of fuel being used to heart rate exists only
insofar as one can equate the heart rate to the workload demand on the
muscle tissue. The two are positively correlated, however the relationship
is neither linear, nor the same across different individuals. One's
theoretical maximum heart rate is largely a function of age (and
co-morbidities), and so setting benchmarks of 50%, 70%, 90% of maximum
heart rate has little meaning in terms of aerobic vs anaerobic performance
of muscle tissue unless you're dealing with a very homogeneous population
(say, a bunch of similarly highly trained elite athletes of the same age).

A 50 year old masters world cup skiier who consistently kicks ass in his
age group has something _very_ different going on in his muscles when he
is exercising at 80% of his maximal heart rate, than does a 50 year old
couch potato at the same % heart rate.

Trained athletes deliver more oxygen to their muscles per unit time, and
there are adaptations that result in the more efficient utilisation of
fatty acids, which leaves them able to maintain a higher level of exertion
before having to switch to anaerobic metabolic pathways, and thus incur a
lesser oxygen debt for the same workload.

In terms of what your wife should be doing... She should aim for a work
rate that she can maintain for a reasonably prolonged length of time. If
she becomes profoundly exhausted very quickly, she's going too hard. If
she can sit/stand there all day, she's not going hard enough. Once she's
worked out which is which, taking note of her plateau heart rate during
those differing workloads will provide useful benchmarks for future
training. Arbitrarily assigning heart rates to represent assumed workload
and extrapolating that to infer fuel source changeover points prior to
setting foot/bum on a trail or piece of exercise equipment is almost as
accurate and reliable an approach as consulting an astrologer.

Oh and unless she's starving herself to death, she won't be "burning
muscle" anytime soon.

Thus endeth the rant... Sorry... hope some of it was a least vaguely
helpful? :-)

Cheers,
Chris