aerobic work for anaerobic sports

[Guest guest]

Ralph Giarnella MD wrote:

<<<I have been following this discussion with some

interest. To this point no one has defined what is

meant by an anaerobic sport. Most of the examples

cited- boxing, tennis, soccer, martial arts etc, the

way I see are in reality high intensity aerobic

sports....

I would be interested in reading the opinions of other

as to what consitutes an anaerobic sport.>>>

Ralph,

Duration Classification Energy Supplied By

1 to 4 seconds Anaerobic ATP (in muscles)

4 to 20 seconds Anaerobic ATP + PC

20 to 45 seconds Anaerobic ATP + PC + Muscle glycogen

45 to 120 seconds Anaerobic, Lactic Muscle glycogen

120 to 240 seconds Aerobic + Anaerobic Muscle glycogen + lactic

240 to 600 seconds Aerobic Muscle glycogen + fatty acids

Energy System recruitment

Although all energy systems basically turn on at the same time the

recruitment of an alternative system occurs when the current energy

system is almost depleted.

The following table provides an approximation of the percentage

contribution of the energy pathways in certain sports. (Fox et al

1993)

Sport ATP-PC and LA LA-O2 O2(aerobic)

Basketball 60 20 20

Fencing 90 10

Field events 90 10

Golf swing 95 5

Gymnastics 80 15 5

Hockey 50 20 30

Distance running 10 20 70

Rowing 20 30 50

Skiing 33 33 33

Soccer 50 20 30

Sprints 90 10

Swimming 1.5km 10 20 70

Tennis 70 20 10

Volleyball 80 5 15

" Table adapted from Fox E. L. et al, The Physiological Basis for

Exercise and Sport, 1993 "

As you can see by the tables above, the sports you mentioned

as being high intensity aerobic are for the most part purely

anaerobic before the primary energy system used is exhausted and then

moves on to the next available energy source.

" Without endurance do you think a boxer would be able to throw a

knock out punch in the 15th round after running around the ring,

dancing and weaving for 45 minutes? "

If the primary energy used in a boxers preparation for a fight

is aerobic, chances are that he wont even be able to reach the 15th

round or throw any kind of punches with speed or power. Just because 1 round

lasts 180 seconds dos not imply that the energy required is

aerobic.

For the sports that you mentioned, boxing, tennis, soccer,

martial arts etc, it would be better to evaluate the energy system

pathway from a more simplistic approach and break it down to a " per

round, per set, per shift(hockey)per play(football)per point(tennis)

view " ect.and from there evaluate the need of the athlete and his

weakness.

Due to the old school mentality that still exists in boxing,

conditioning outside the ring a 3:1 ratio is still very predominant.

In my opinion, training them that way outside the ring will do

very little to help them and will probably cause injury from overuse.

In boxing, basketball, baseball, hockey, tennis, soccer, martial

arts, they always explode with high energy output followed by a state

of rest and " actively resting " (which for most well conditioned

athletes is like a walk in the park) so on and so forth until resting

for the sport given interval and back again. Boxing 1 minute per

round, tennis has more frequent breaks per set and per match and for

the most part energy output is very high and short from a point

scored to the next. Baseball being purely (AAP) alactic anaerobic

power, in competition(game time)

In my opinion, a few major key components in all sports is

strength-endurance and the ability to recuperate after a high energy

output (being able to perform at peak levels under repetitive high

force output conditions)

I hope this answers your question somewhat as there is much more

we can discuss about this topic.EX:limit strength,strength-

speed,speed strength.

Terry Mavroudis

Montreal,Canada

[Guest guest]

--- terry_thebeast_trainz

wrote:

> Duration Classification Energy Supplied

> By

> 1 to 4 seconds Anaerobic ATP (in muscles)

> 4 to 20 seconds Anaerobic ATP + PC

> 20 to 45 seconds Anaerobic ATP + PC + Muscle

> glycogen

> 45 to 120 seconds Anaerobic, Lactic Muscle

> glycogen

> 120 to 240 seconds Aerobic + Anaerobic Muscle

> glycogen + lactic

> 240 to 600 seconds Aerobic Muscle glycogen +

> fatty acids

>

> Energy System recruitment

>

> Although all energy systems basically turn on at the

> same time the

> recruitment of an alternative system occurs when the

> current energy

> system is almost depleted.

>

> The following table provides an approximation of the

> percentage

> contribution of the energy pathways in certain

> sports. (Fox et al

> 1993)

>

> Sport ATP-PC and LA LA-O2

> O2(aerobic)

> Basketball 60 20

> 20

> Fencing 90 10

> Field events 90 10

> Golf swing 95 5

> Gymnastics 80 15

> 5

> Hockey 50 20 30

> Distance running 10 20

> 70

> Rowing 20 30

> 50

> Skiing 33 33

> 33

> Soccer 50 20

> 30

> Sprints 90 10

> Swimming 1.5km 10 20

> 70

> Tennis 70 20

> 10

> Volleyball 80 5

> 15

>

> " Table adapted from Fox E. L. et al, The

> Physiological Basis for

> Exercise and Sport, 1993 "

>

> As you can see by the tables above, the

> sports you mentioned

> as being high intensity aerobic are for the most

> part purely

> anaerobic before the primary energy system used is

> exhausted and then

> moves on to the next available energy source.

>

> " Without endurance do you think a boxer would

> be able to throw a

> knock out punch in the 15th round after running

> around the ring,

> dancing and weaving for 45 minutes? "

>

>

> If the primary energy used in a boxers

> preparation for a fight

> is aerobic, chances are that he wont even be able to

> reach the 15th

> round or throw any kind of punches with speed or

> power. Just because 1 round lasts 180 seconds dos

> not imply that the energy required is

> aerobic.

> For the sports that you mentioned, boxing,

> tennis, soccer,

> martial arts etc, it would be better to evaluate the

> energy system

> pathway from a more simplistic approach and break it

> down to a " per

> round, per set, per shift(hockey)per

> play(football)per point(tennis)

> view " ect.and from there evaluate the need of the

> athlete and his

> weakness.

> Due to the old school mentality that still

> exists in boxing,

> conditioning outside the ring a 3:1 ratio is still

> very predominant.

> In my opinion, training them that way outside

> the ring will do

> very little to help them and will probably cause

> injury from overuse.

> In boxing, basketball, baseball, hockey,

> tennis, soccer, martial

> arts, they always explode with high energy output

> followed by a state

> of rest and " actively resting " (which for most well

> conditioned

> athletes is like a walk in the park) so on and so

> forth until resting

> for the sport given interval and back again. Boxing

> 1 minute per

> round, tennis has more frequent breaks per set and

> per match and for

> the most part energy output is very high and short

> from a point

> scored to the next. Baseball being purely (AAP)

> alactic anaerobic

> power, in competition(game time)

> In my opinion, a few major key components in

> all sports is

> strength-endurance and the ability to recuperate

> after a high energy

> output (being able to perform at peak levels under

> repetitive high

> force output conditions)

>

>

>

> I hope this answers your question somewhat as

> there is much more

> we can discuss about this topic.EX:limit

> strength,strength-

> speed,speed strength.

>

>

> Terry Mavroudis

> Montreal,Canada

Terry

Lets take a look at each of the systems you describe.

Firstly the ATP PCR systems. This system is utilized

by all muscles fiber whether they be type I, type IIa

or type IIb. It is the final step in the production

of energy that allows the all fibers to contract.

This system has enough stored energy to last from

5-15 seconds. An yes this is purely anaerobic because

it does not require Oxygen to make the system go.

This system is also called Alactic system since lactic

acid is not a byproduct.

The important question is what happens once this

storage of this energy is depleted? If the ATP-PCR

system is not restored to its original level the

muscle can no longer contract.

In order to replenish the ATP-PCR system you can use

the glycolytic system. The glycolytic systems

consists of two phases. The anaerobic phase and the

aerobic phase.

When glucose is fully metabolized to produce ATP at

total of 42+ units of ATP are produced for every unit

of glucose utilized.

In the first phase (anaerobic) 6 units of ATP are

produced along with 2 units of lactic acid. That is

less than 15% of the energy potential energy in

glucose is utilized during the anaerobic phase of the

glycolytic system. The rest of the energy resides in

the lactic acid byproduct.

It is estimated that a well trained athlete may store

as much as 400 grams of glycogen in all the muscles of

the body (another 90+ is stored in the liver). That

400 grams of glycogen is capable of producing 1600

calories of energy that can be utilized by muscles.

Now if less than 15% is utilized to produce ATP that

means the maximum energy that can be produced using

the anaerobic energy system is 240 calories. Now that

is assuming that all the glycogen stored in the body

are stored only in the muscles utilized in the

particular sport. But that 400 grams is distributed

to ALL of the muscles.

“A muscle fiber’s rate of energy use during exercise

can be 200 times greater than at rest. The ATP-PCR

and glycolytic systems alone cannot supply all the

needed energy for all out activity lasting more than 2

minutes, nor are they efficient for generating ATP for

long duration activity.” (Physiology of Sport and

Exercise and Costill 3rd edition pg. 125)

What happens when you run out of glycogen. This

situation is sports if called hitting the wall or

bonking.

Before bonking occurs we have to turn to the Oxidative

system- also called the Aerobic system. This

Oxidative system only takes place in mitochondria and

specifically the Citric acid cycle also known as the

Krebs cycle.

The mitochondria are not present in Type IIb fibers

which are purely anaerobic fibers. They are present

howeve in abundance in the Type I fibers (slow

oxidative) and the Type IIa fibers (which are also

known as the fast oxidative glycolytic fibers -FOG).

I will get back to the Type IIa fibers and how they

become Oxidative and the type of training required

develop these fibers.

But first let us get back to the second phase of the

glycolytic energy system. In the first phase 6 units

of ATP were produced along with lactic acid. In the

presence of Oxygen lactic acid is converted to

Pyruvate. Pyruvate can now enter the the second phase

of the glycolytic system. In this system the pyruvate

is completely broken down and 37-39 units of ATP are

produced. The Krebs cycle is also the final pathway

for the metabolism of fat.

So out of a total of a possible 43-45 units of ATP

which can be produced from glucose more than 85% is

produced in the oxidative system and less than 15% is

produced anaerobically.

For the moment lets get back to the Type IIb fibers.

As stated above these fibers do not have mitochondria

and therefore are incapable of utilizing the energy in

lactic acid. So what happens to the lactic acid.

Well it becomes lactate which is a salt and exits

leaves the fiber and enters the blood stream. It can

then be taken up by neighboring type IIa or typeI

fibers and enter the mitochondria in these fibers and

becomes pyruvate which is subsequently metabolized in

the Krebs cycle. Or the lactate can proceed to other

organs in the body and utilized for energy or enter

the liver where it is utilized to make more glucose.

To this point more than 85% of the energy produced

from the utilization of glycogen is produced

aerobically. We have not even discussed the

contribution of the typeI fibers and fat. In a well

trained athlete fat can be utilized up to an intensity

of 75% or more of VO2 max.

I would now like to discuss the role of type IIa

fibers because these fibers are the key to success in

high intensity sports activity.

These fibers work both aerobically as well as

anaerobically. The lactic acid that they produce

during an anaerobic phase can then be converted to

pyruvate and enter the krebs cycle once the Oxygen

supply is restored to produce more ATP.

These are the fibers which are recruited when the

intensity of activity approaches 65-70% of VO2max and

are the primary fibers recruited during activity which

at 75-100% VO2max.

“Endurance training has been shown to reduce the

percentage of type IIb fibers while increasing the

percentage of typeIIa fibers.” (Physiology of Sport

and Exercise ( and Costill 3rd edition pg. 49)

Not only are is the percentage of type IIa fibers

increased with high intensity endurance training but

the concentration of mitochondria are also increased

in these fibers.

Training at what is often referred to as the Lactate

threshold (85-95%VO2max) enhances these fibers. High

intensity interval training utilizes these fibers.

This is high intensity but still AEROBIC.

“Muscle fiber types in rats have changed in response

to 15 weeks of high intensity treadmill training,

resulting in an increase in type I and type IIa fibers

and a decreased in type IIb fibers.”

" Staron and coworkers found evidence of fiber-type

transformation in women as a result of heavy

resistance training. Following a 20-week heavy

resistance training program for the lower extremity,

the mean percentage of type IIb fibers decreased

significantly, but the mean percentage of type IIa

fibers increased. (Staron et al European Journal of

Applied Physiology) "

" The reduction of type IIb fibers and the increase in

type IIa fibers with resistance training has been

consistently reported in a number of subsequent

studies.

( and Costill 3rd edition pg. 99) "

If you examine the tables cited as to energy systems,

much of what you have attributed to anaerobic work is

really high intensity aerobic work performed by the

type IIa fibers.

There is not enough glycogen stored in the muscles to

sustain more than 10 minutes of high intensity

anaerobic work.

Ralph Giarnella MD

Southington, CT

[Guest guest]

A few comments regarding Dr. Giarnella's response to Terry and on

the overall discussion on this training topic.

First of all, Dr. Giarnella you did a great job of supporting your

comments by citing Wilmore & Costill's 3rd edition, but where is it

stated that there are " no " mitochondria in Type IIb fibers? You make

this comment twice yet in Wilmore & Costill, as well as in McCardle,

Katch & Katch, and Marieb and others, Type IIb fibers are stated as

having few or low numbers of mitochondria and a " low " oxidative

capacity, not " none " (pg 45-46).

This fact is further supported by another study you mention, but

failed to provide all the information. The 15 week study involving

rats is also stated as showing a transition of IIb fibers to IIa.

This could not happen if mitochondria were not present in the Type

IIb fibers.

Dr Giarnella, I'm also confused at what you were trying to get at

overall in relationship to the original discussion on training. Or

did you just feel Terry needed a physiology course? Furthermore, by

presenting the Staron study, one might conclude that Type IIb fibers

aren't necessary and neither is it necessary to train anaerobically?

The studies you cited were from a section on whether or not fiber

types can be altered through training. The section was not written

to support methods of training for optimal performance. (On a side

note, my review of research in 1993 regarding women and strength

training showed that most methods were not the same as utilized by

men for improvements in strength and power. I don't have access to

the Staron study now, but it was published in 1990 and so I'd

question it's use of actual " heavy " .

So, if I remember correctly now, the original question was relative

to a gentleman wishing to run a marathon, and later compete in

Martial Arts - fortunately with a couple of months in between. With

the marathon being first (if I remember correctly),

cardiorespiratory endurance will be enhanced as a result. According

to Wilmore & Costill, 3rd edition (pg 298), " regardless of the sport

or activity, fatigue represents a major deterrent to optimal

performance...all athletes can benefit from maximizing their

endurance. " Now, a marathon constitutes a time frame well beyond

what would be needed and it should be kept in mind that gains in

muscular strength and power are less when strength training is

combined with endurance training, but aerobic capacity with

endurance training is not attenuated by including a resistance

training program. So, the concern will be if overall strength and

power is affected long term. I believe if you were at a peak prior

to training for the run, you should be able to retain a large

majority of that strength and power and then replace any levels lost

in the couple of months prior to the event. Because of the time

frame between the marathon and m.a. competition, it may not have

great effects, but that is what we do not know!

" Very little research data are available concerning multisport

training...it is important to determine how best to partition the

avaliable training time to optimize performance in each sport. "

(Wilmore & Costill pg 298)

Lastly, The energy proportion graph from , Fahey, and White

(1996)in Exercise Physiology: Human Bioenergetics and Its

Applications seems to be a little more clear on aerobic and

anaerobic without confusing one with which fuels are being used:

Duration %Anaerobic %Aerobic

1-3 sec. 100 0

10 sec. 90 10

30 sec. 80 20

60 sec. 70 30

2 min. 60 40

4 min. 35 65

10 min. 15 85

30 min 5 95

1 hour 2 98

Just as with the controversy regarding functional training vs.

traditional strength training - both aerobic and anaerobic training

are necessary but more research is needed to better outline

appropriate training parameters. The winner of a marathon between

two runners with the same V02max will be the runner with the greater

anaerobic capacity just as the baseball player with the higher

aerobic capacity will better survive a double header than the player

who does not train aerobically. But, because aerobic training

affects strength and power, we have to determine an optimal level of

training. One suggestion is to train to develop a peak VO2max prior

to beginning to develop strength and power and then maintain that

level by training at least 3x a week at 70% VO2max (Wilmore &

Costill pg. 398).

MS, ATC, CSCS

Spanaway, WA

>

>

> > Duration Classification Energy Supplied

> > By

> > 1 to 4 seconds Anaerobic ATP (in muscles)

> > 4 to 20 seconds Anaerobic ATP + PC

> > 20 to 45 seconds Anaerobic ATP + PC + Muscle

> > glycogen

> > 45 to 120 seconds Anaerobic, Lactic Muscle

> > glycogen

> > 120 to 240 seconds Aerobic + Anaerobic Muscle

> > glycogen + lactic

> > 240 to 600 seconds Aerobic Muscle glycogen +

> > fatty acids

> >

> > Energy System recruitment

> >

> > Although all energy systems basically turn on at the

> > same time the

> > recruitment of an alternative system occurs when the

> > current energy

> > system is almost depleted.

> >

> > The following table provides an approximation of the

> > percentage

> > contribution of the energy pathways in certain

> > sports. (Fox et al

> > 1993)

> >

> > Sport ATP-PC and LA LA-O2

> > O2(aerobic)

> > Basketball 60 20

> > 20

> > Fencing 90 10

> > Field events 90 10

> > Golf swing 95 5

> > Gymnastics 80 15

> > 5

> > Hockey 50 20 30

> > Distance running 10 20

> > 70

> > Rowing 20 30

> > 50

> > Skiing 33 33

> > 33

> > Soccer 50 20

> > 30

> > Sprints 90 10

> > Swimming 1.5km 10 20

> > 70

> > Tennis 70 20

> > 10

> > Volleyball 80 5

> > 15

> >

> > " Table adapted from Fox E. L. et al, The

> > Physiological Basis for

> > Exercise and Sport, 1993 "

> >

> > As you can see by the tables above, the

> > sports you mentioned

> > as being high intensity aerobic are for the most

> > part purely

> > anaerobic before the primary energy system used is

> > exhausted and then

> > moves on to the next available energy source.

> >

> > " Without endurance do you think a boxer would

> > be able to throw a

> > knock out punch in the 15th round after running

> > around the ring,

> > dancing and weaving for 45 minutes? "

> >

> >

> > If the primary energy used in a boxers

> > preparation for a fight

> > is aerobic, chances are that he wont even be able to

> > reach the 15th

> > round or throw any kind of punches with speed or

> > power. Just because 1 round lasts 180 seconds dos

> > not imply that the energy required is

> > aerobic.

> > For the sports that you mentioned, boxing,

> > tennis, soccer,

> > martial arts etc, it would be better to evaluate the

> > energy system

> > pathway from a more simplistic approach and break it

> > down to a " per

> > round, per set, per shift(hockey)per

> > play(football)per point(tennis)

> > view " ect.and from there evaluate the need of the

> > athlete and his

> > weakness.

> > Due to the old school mentality that still

> > exists in boxing,

> > conditioning outside the ring a 3:1 ratio is still

> > very predominant.

> > In my opinion, training them that way outside

> > the ring will do

> > very little to help them and will probably cause

> > injury from overuse.

> > In boxing, basketball, baseball, hockey,

> > tennis, soccer, martial

> > arts, they always explode with high energy output

> > followed by a state

> > of rest and " actively resting " (which for most well

> > conditioned

> > athletes is like a walk in the park) so on and so

> > forth until resting

> > for the sport given interval and back again. Boxing

> > 1 minute per

> > round, tennis has more frequent breaks per set and

> > per match and for

> > the most part energy output is very high and short

> > from a point

> > scored to the next. Baseball being purely (AAP)

> > alactic anaerobic

> > power, in competition(game time)

> > In my opinion, a few major key components in

> > all sports is

> > strength-endurance and the ability to recuperate

> > after a high energy

> > output (being able to perform at peak levels under

> > repetitive high

> > force output conditions)

> >

> >

> >

> > I hope this answers your question somewhat as

> > there is much more

> > we can discuss about this topic.EX:limit

> > strength,strength-

> > speed,speed strength.

> >

> >

> > Terry Mavroudis

> > Montreal,Canada

>

> Terry

> Lets take a look at each of the systems you describe.

>

> Firstly the ATP PCR systems. This system is utilized

> by all muscles fiber whether they be type I, type IIa

> or type IIb. It is the final step in the production

> of energy that allows the all fibers to contract.

>

> This system has enough stored energy to last from

> 5-15 seconds. An yes this is purely anaerobic because

> it does not require Oxygen to make the system go.

> This system is also called Alactic system since lactic

> acid is not a byproduct.

>

> The important question is what happens once this

> storage of this energy is depleted? If the ATP-PCR

> system is not restored to its original level the

> muscle can no longer contract.

>

> In order to replenish the ATP-PCR system you can use

> the glycolytic system. The glycolytic systems

> consists of two phases. The anaerobic phase and the

> aerobic phase.

>

> When glucose is fully metabolized to produce ATP at

> total of 42+ units of ATP are produced for every unit

> of glucose utilized.

>

> In the first phase (anaerobic) 6 units of ATP are

> produced along with 2 units of lactic acid. That is

> less than 15% of the energy potential energy in

> glucose is utilized during the anaerobic phase of the

> glycolytic system. The rest of the energy resides in

> the lactic acid byproduct.

>

> It is estimated that a well trained athlete may store

> as much as 400 grams of glycogen in all the muscles of

> the body (another 90+ is stored in the liver). That

> 400 grams of glycogen is capable of producing 1600

> calories of energy that can be utilized by muscles.

> Now if less than 15% is utilized to produce ATP that

> means the maximum energy that can be produced using

> the anaerobic energy system is 240 calories. Now that

> is assuming that all the glycogen stored in the body

> are stored only in the muscles utilized in the

> particular sport. But that 400 grams is distributed

> to ALL of the muscles.

>

> " A muscle fiber's rate of energy use during exercise

> can be 200 times greater than at rest. The ATP-PCR

> and glycolytic systems alone cannot supply all the

> needed energy for all out activity lasting more than 2

> minutes, nor are they efficient for generating ATP for

> long duration activity. " (Physiology of Sport and

> Exercise and Costill 3rd edition pg. 125)

>

> What happens when you run out of glycogen. This

> situation is sports if called hitting the wall or

> bonking.

>

> Before bonking occurs we have to turn to the Oxidative

> system- also called the Aerobic system. This

> Oxidative system only takes place in mitochondria and

> specifically the Citric acid cycle also known as the

> Krebs cycle.

>

> The mitochondria are not present in Type IIb fibers

> which are purely anaerobic fibers. They are present

> howeve in abundance in the Type I fibers (slow

> oxidative) and the Type IIa fibers (which are also

> known as the fast oxidative glycolytic fibers -FOG).

>

> I will get back to the Type IIa fibers and how they

> become Oxidative and the type of training required

> develop these fibers.

>

> But first let us get back to the second phase of the

> glycolytic energy system. In the first phase 6 units

> of ATP were produced along with lactic acid. In the

> presence of Oxygen lactic acid is converted to

> Pyruvate. Pyruvate can now enter the the second phase

> of the glycolytic system. In this system the pyruvate

> is completely broken down and 37-39 units of ATP are

> produced. The Krebs cycle is also the final pathway

> for the metabolism of fat.

>

> So out of a total of a possible 43-45 units of ATP

> which can be produced from glucose more than 85% is

> produced in the oxidative system and less than 15% is

> produced anaerobically.

>

> For the moment lets get back to the Type IIb fibers.

> As stated above these fibers do not have mitochondria

> and therefore are incapable of utilizing the energy in

> lactic acid. So what happens to the lactic acid.

> Well it becomes lactate which is a salt and exits

> leaves the fiber and enters the blood stream. It can

> then be taken up by neighboring type IIa or typeI

> fibers and enter the mitochondria in these fibers and

> becomes pyruvate which is subsequently metabolized in

> the Krebs cycle. Or the lactate can proceed to other

> organs in the body and utilized for energy or enter

> the liver where it is utilized to make more glucose.

>

> To this point more than 85% of the energy produced

> from the utilization of glycogen is produced

> aerobically. We have not even discussed the

> contribution of the typeI fibers and fat. In a well

> trained athlete fat can be utilized up to an intensity

> of 75% or more of VO2 max.

>

> I would now like to discuss the role of type IIa

> fibers because these fibers are the key to success in

> high intensity sports activity.

>

> These fibers work both aerobically as well as

> anaerobically. The lactic acid that they produce

> during an anaerobic phase can then be converted to

> pyruvate and enter the krebs cycle once the Oxygen

> supply is restored to produce more ATP.

>

> These are the fibers which are recruited when the

> intensity of activity approaches 65-70% of VO2max and

> are the primary fibers recruited during activity which

> at 75-100% VO2max.

>

> " Endurance training has been shown to reduce the

> percentage of type IIb fibers while increasing the

> percentage of typeIIa fibers. " (Physiology of Sport

> and Exercise ( and Costill 3rd edition pg. 49)

> Not only are is the percentage of type IIa fibers

> increased with high intensity endurance training but

> the concentration of mitochondria are also increased

> in these fibers.

>

> Training at what is often referred to as the Lactate

> threshold (85-95%VO2max) enhances these fibers. High

> intensity interval training utilizes these fibers.

> This is high intensity but still AEROBIC.

>

> " Muscle fiber types in rats have changed in response

> to 15 weeks of high intensity treadmill training,

> resulting in an increase in type I and type IIa fibers

> and a decreased in type IIb fibers. "

>

> " Staron and coworkers found evidence of fiber-type

> transformation in women as a result of heavy

> resistance training. Following a 20-week heavy

> resistance training program for the lower extremity,

> the mean percentage of type IIb fibers decreased

> significantly, but the mean percentage of type IIa

> fibers increased. (Staron et al European Journal of

> Applied Physiology) "

>

> " The reduction of type IIb fibers and the increase in

> type IIa fibers with resistance training has been

> consistently reported in a number of subsequent

> studies.

> ( and Costill 3rd edition pg. 99) "

>

> If you examine the tables cited as to energy systems,

> much of what you have attributed to anaerobic work is

> really high intensity aerobic work performed by the

> type IIa fibers.

>

> There is not enough glycogen stored in the muscles to

> sustain more than 10 minutes of high intensity

> anaerobic work.

>

> Ralph Giarnella MD

> Southington, CT

>