Post by carruthersjam on Jul 21, 2007 3:39:21 GMT -8
Zatsiorsky VM "The Meaning and Maintenance of Weight Training
essential for increase in Muscle Mass" Theory & Practice of Physical
Culture, 2:24-26, 1963.
Mathematical determinations were presented to show the relationship
between the total weight of the athlete and the maximum weight which
he can lift . Participation in strength exercises leads to an
increase in the physiological cross-section of the muscle mass.
Hhowever, weightlifters can significantly improve their results by
staying in their respective weight categories. Therefore, improvement
in the conditioned reflex coordination of movement becomes most
important.
Variations for increasing muscle mass are used by "culturalists", as
witnessed in American publications such as Health and Strength,
Muscle Power, and others. In principle, we in this country are not
receptive to the form which is developed in the culturalist movement,
even if strength exercises are involved to some measure and change
the form of the body. It is necessary, however, that these
undertakings do not stop at one's body alone but that they play a
role in the overall process of total physical education. Training by
the culturalist methods can broaden one's mental outlook and can be
beneficial for one. Intelligent inclusion in the training exercises
for increasing muscle mass is one of the ways for increasing
strength.
Tied in with this, one must remember that gained strength stays
longer in those cases where its growth occurs at the same time as
growth in muscle mass: Strength is lost faster when muscle mass is
not increased concurrently. In several sports such as throwing ,
acrobatics and others it is sometimes necessary to increase one's
total weight and for this, this method may be good. The most
important aspects of this method of training is the use of 10
repetition maxima for each exercise, which is correct. If one can do
more than 8-12 maximum repetitions, the resistance is increased. For
smaller muscle groups there is less muscle mass and it is necessary
to increase the number of repetitions to 20-25. This is explained by
the fact that restoration processes in small muscle groups take place
at a much faster rate. One workout per day is sufficient and it is
important for promotion of the adaptation processes.
One of the most important methods is the "flush" to create activation
of the circulatory system . In this case they perform 10 maximum
repetitions for three sets with little rest in between each set. The
performer then goes on to another exercise to address all aspects of
the muscle. His muscle mass can be increased so that limb girth can
increase by up to 3.8 centimeters.
Another method is "cramping", which is done at the end of the above
regime. The performer lifts weight greater than he can lift for the
full range of motion. It is lifted to such an extent so that at
least some movement is possible for a short time in order that it can
bring out the "sick" appearance as seen in conditions of static
circulation. At times, this causes tissue stretching.... In this
method there is shortening and loss of elasticity in the muscles;
therefore, one should always execute some dynamic movements over a
full range of motion after this type of activity.
Choosing the activity for one muscle group is a complicated problem
for the effective training of athletes. In order to activate a
certain muscle group, they use the "cheating" method. When they lift
heavy weights, neighbouring muscle groups come into action to assist
in the execution of this lift. Exercises in such cases are fulfilled
with incorrect technique, as there is a slight change in the basic
structure of the movement. The exercises should be fulfilled with
great resistance and with the ability to repeat it many times.
These methods are good for increasing muscle mass. Comparing this
training with the training of weightlifters, one can see that the
basic difference is in the aspiration of how to increase the
intensity of the changed processes in the muscles, sometimes leading
to a complete change. The basic training of weightlifters (general
training directed toward development of strength without a
significant increase of muscle mass) lies in the conditioned systems
of basic reflexes, which helps insure the best results between the
muscles and internal muscle coordination. Because of this, it is
essential to work as near as possible with the heaviest weights, with
few repetitions each time, and with extended intervals of rest in
between sets. Then, execution of every exercise will be along the
lines of coordination corresponding fully to the movement with
maximum resistance. Also it will help achieve an optimum, but not
delayed fatigue condition in the central nervous system which, in its
own limits, aids in the formation of very fine basic reflexes which
are realized in the cortex.
One can say that the training method used by "culturalists" is
directed towards intensifying the general processes in the muscles,
while training of weightlifters is for establishing corresponding
basic reflexive processes in the central nervous system.
------------
Posted by Dr Tony Shield
I read with interest the recent communications regarding muscle
hypertrophy and whether 'fatigue' acted as a stimulus for it. This
concept is not new (Ingwall, 1976; Rogozkin, 1976). There are also a
number of empirical reasons to believe that the metabolic
consequences of resistance training (and other forms of exercise) may
stimulate hypertrophy. For example, the training practices of many
bodybuilders (moderate resistances, medium to high reps/set,
continuous tension and short inter-set rest periods) appear geared to
maximising metabolic stress rather than muscular tension.
Furthermore, I was surprised by the reticence of many list members to
accept the idea that metabolic stress had a role in mediating muscle
hypertrophy. Thus, despite coming in late on this discussion I wanted
to add my 2 cents worth.
Exercise scientists have been interested, for some years now, in
understanding the mechanisms by which resistance training stimulates
hypertrophy (eg Jones and Rutherford, 1987; Takarada et al., 2000a;
Takarada et al., 2000b; Takarada et al., 2000c) and strength gains
(eg Carey-Smith and Rutherford, 1995; Rooney et al, 1994; Schott et
al., 1995; Shinohara et al., 1998). Particular attention has been
given to the question of whether tension and metabolic stress might
both act to stimulate muscle growth, either in synergy or via
parallel mechanisms.
No one is suggesting that tension is not an important stimulus. We
know that tension, in the form of chronic stretch, can stimulate
muscle growth in the absence of metabolic stress (Antonio and Gonyea,
1993). However, there are a number of reasons to believe that
metabolic stress acts as an additional stimulus, particularly when
resistance training takes the form of medium to high reps with short
rest periods between sets.
Recently those interested in the training of the elderly and frail
have taken up this work because if metabolic stress is a stimulus it
should be possible to stimulate some hypertrophy in populations that
might otherwise not be able to engage in conventional resistance
training because of the heavy loads involved. (This is hardly
a 'trivial' issue if you have osteoporosis or joint degeneration)
The hypothesis that is actually being tested in these studies (Jones
and Rutherford, 1987; Takarada et al., 2000a; Takarada et al., 2000b)
is that the metabolic stress induced by resistance training is a
stimulus for hypertrophy.
Metabolic stress takes the form of substrate depletion (eg. creatine
phosphate breakdown) and the consequent build up of metabolites such
as creatine, Pi, ADP, AMP, H+, lactate or something else! The exact
stimulant is not identified any more clearly than this and it is
probably naive to consider whether any one of these products acts
alone as a stimulus. (Lactic acid gets blamed for almost everything
in exercise science despite a distinct lack of evidence). Clearly,
there is a lot more going on at the cellular level than acidosis! For
example, it has been hypothesised that the occlusion of blood flow in
a contracting muscle and the resulting hypoxia stimulates free
radical production (Takarada et al., 2000b). In addition to causing
tissue damage, there are good reasons to believe that free radicals
may have a role in the regulation of muscle growth (see Takarada et
al., 2000b for the references).
The most convincing evidence that metabolic stress acts as a powerful
stimulant for hypertrophy comes from Takarada et al., (2000b) (as
pointed out previously by Gus Karageorgos). In this study a fairly
conventional moderate-resistance training program (employing ~80% 1
RM) for the elbow flexors was compared to a light-resistance program
(employing ~50% 1 RM) with partial vascular occlusion, a light-
resistance program (employing ~50% 1 RM) without vascular occlusion
and no training (control group). The vascular occlusion (applied via
a blood pressure cuff) ensured that metabolites produced during
exercise were not removed from the muscle, thus maximising metabolic
stress.
After 16 weeks training the changes in muscle CSA for biceps brachii
and brachialis were significantly greater for the 80% 1 RM group and
50%-with-occlusion group than the 50% without occlusion group. No
significant differences were found between the 80% 1 RM group and 50%-
with-occlusion group but the trend was for the 50% with-occlusion
group to exhibit greater hypertrophy, particularly in the brachialis.
Interestingly, the triceps of the occlusion group increased in size
by approximately 13-14% without being trained.
The major limitation of the study is that vascular occlusion may have
had its anabolic effects directly via increasing the metabolite load
or indirectly by raising the level of recruitment necessary to lift
the light loads. However, the former possibility remains plausible
when one considers other findings (Takarada et al., 2000a and 2000c).
Firstly, growth hormone (GH) release has been observed to increase
290 fold over rest levels when extremely light (~20% 1 RM) resistance
training is combined with vascular occlusion. Exercise alone resulted
in negligible changes in GH (Takarada et al., 2000a). Secondly, a
study of young subjects demonstrated that the disuse atrophy caused
by bed rest was prevented by occasional vascular occlusion in the
absence of exercise (Takarada et al., 2000c). Presumably both effects
were mediated by GH's action on IGF-1 which has potent anabolic and
anti-catabolic effects.
It might also pay to consider some observations regarding creatine
that could arguably unify the creatine's ergogenic effects with the
metabolic stress hypothesis. Firstly, creatine induces significant
hypertrophy in unexercised embryonic chick muscle (Ingwall, 1976).
Secondly, creatine appears to stimulate protein synthesis by
increasing MRF4 and myogenin expression in adult humans undergoing
resistance training (Hespel et al., 2001). Finally creatine is a
metabolite produced during high intensity exercise such as resistance
training. One might therefore hypothesise that creatine accumulation
acts to stimulate hypertrophy after resistance training and that
supplementary creatine magnifies this effect.
Regarding some of the valid critiques offered by list members.
1.. It is true that most of the work so far has been carried out on
the relatively untrained elderly. Work is clearly needed on younger
and more highly trained groups. However, in the aforementioned study
the effect of light resistance training without occlusion was almost
zero so it can not be said that the 50% load was sufficient in the
absence of vascular occlusion.
2.. Powerlifters and weightlifters may trigger hypertrophy almost
solely via tension mediated mechanisms while programs employed by
bodybuilders may trigger hypertrophy via a combination of tension and
metabolic stress mechanisms. The recent research shows that those who
employ lighter loads (<50% 1 RM) may still stimulate muscle growth
via maximising the metabolic stress of the workout - even if the
tension levels alone are insufficient.
References
Antonio & Gonyea, (1993); Med. Sci. Sports & Ex. 25(12):1333-1345).
Hespel et al., (2001) J Physiol 15;536(Pt 2):625-33
Ingwall (1976); Supp. Circ. Res 38(5):I115-123
Jones and Rutherford, (1987). J Physiol, 391:1-11
Rogozkin, (1976). Med Sci Sports, 8(1): 1-4
Takarada et al., (2000a). J Appl Physiol, 88: 61-65
Takarada et al., (2000b). J Appl Physiol, 88: 2097-2106
Takarada et al., (2000c). Med Sci Sports Exerc 32(12):2035-9
-------------
Note too, in addition to the latter information I would encourage you
to read some of the work by Tom Incledon, James Krieger, Jerry Telle,
Christian Thibaudeau, Duncan MacDougall and Digby Sale.
-----
Overview of the 3rd Annual SWIS Symposium
by John M. Berardi
www.t-mag.com/nation_articles/186swis.html
Neural Adaptations to Strength Training — Digby Sale, Ph.D.
Dr. Sale is the real deal! This guy is an accomplished researcher
whose work has contributed more to the knowledge of the interaction
between training and the nervous system than anyone else out there.
In addition, Dr. Sale is an interesting speaker and this is rare for
them "academic types." Here are a few things Dr. Sale presented:
• Muscles are engines but they need an engine controller. The central
nervous system is that controller.
• Increased muscle force is developed through two ways:
a. Increased motor unit recruitment — Important up to 50% of maximum
voluntary contraction.
b. Increased motor unit firing rate — Important above 50% of maximum
voluntary contraction.
• Motor neurons and muscle fibers are recruited in order from small
to large.
• During the first rep of an exercise using 50% of 1RM, you recruit
75% of fibers. With each rep you recruit more motor units until
failure. At this point you should have activated 100% of fibers.
• During the first rep of an exercise using 90% of 1RM, you recruit
nearly 100% of max. Each rep after is accomplished through increase
motor unit firing rate.
• Training to failure ensures you will reach nearly 100% of muscle
fibers. If you stop short of failure you may not activate all fibers
and the last few fibers recruited are the biggest ones that grow best.
• Fast contractions require high rates of motor unit firing rate.However, if your intention is to contract quickly but the weight
doesn't move quickly (because it's too heavy), rapid firing rates
will result.
Mechanisms of Muscle Hypertrophy — Dunchan MacDougall, Ph.D.
Like Dr. Sale, Dr. MacDougall is a veteran of the research scene. In
fact, he's so veteran that he's been retired for 2 years. Although I
was totally into his work, the less science savvy were bored to
tears. All this science stuff can be heavy to the uninitiated. It was
sad to see people walking out during this talk. Nearly every slide in
this 90-minute presentation was work that he did himself, making this
presentation a chronical of the man's entire successful career.
Unfortunately, though, the message was lost through the messenger. To
his credit, most of what we know about how weight training creates
bigger muscles can be attributed to 30 years of Dr. MacDougall's
work. Here are the highlights:
• Resistance exercise causes increases in muscle protein synthesis
that peak about 24 hours later and persist for about 36-48 hours.
• Although some people think the anabolic hormone response to
exercise plays a role in muscle growth, this probably isn't true.
Hormones peak immediately after exercise while protein synthesis
peaks much later.
• Training induced increases in protein synthesis occur in starved
animals, in the absence of anabolic hormones, and even in muscle with
no nervous system innervation.
• Increased protein synthesis — manifested as new protein — is added
to the outside of muscle cells, making the cells larger. Likewise,
the splitting of the myofibrils creates a greater number of
myofibrils, all of which are capable of growth.
• Evidence does not support the idea that muscle fiber hyperplasia
occurs in humans.
• Genetics and training play the largest roles in determining how
large a muscle can become.
essential for increase in Muscle Mass" Theory & Practice of Physical
Culture, 2:24-26, 1963.
Mathematical determinations were presented to show the relationship
between the total weight of the athlete and the maximum weight which
he can lift . Participation in strength exercises leads to an
increase in the physiological cross-section of the muscle mass.
Hhowever, weightlifters can significantly improve their results by
staying in their respective weight categories. Therefore, improvement
in the conditioned reflex coordination of movement becomes most
important.
Variations for increasing muscle mass are used by "culturalists", as
witnessed in American publications such as Health and Strength,
Muscle Power, and others. In principle, we in this country are not
receptive to the form which is developed in the culturalist movement,
even if strength exercises are involved to some measure and change
the form of the body. It is necessary, however, that these
undertakings do not stop at one's body alone but that they play a
role in the overall process of total physical education. Training by
the culturalist methods can broaden one's mental outlook and can be
beneficial for one. Intelligent inclusion in the training exercises
for increasing muscle mass is one of the ways for increasing
strength.
Tied in with this, one must remember that gained strength stays
longer in those cases where its growth occurs at the same time as
growth in muscle mass: Strength is lost faster when muscle mass is
not increased concurrently. In several sports such as throwing ,
acrobatics and others it is sometimes necessary to increase one's
total weight and for this, this method may be good. The most
important aspects of this method of training is the use of 10
repetition maxima for each exercise, which is correct. If one can do
more than 8-12 maximum repetitions, the resistance is increased. For
smaller muscle groups there is less muscle mass and it is necessary
to increase the number of repetitions to 20-25. This is explained by
the fact that restoration processes in small muscle groups take place
at a much faster rate. One workout per day is sufficient and it is
important for promotion of the adaptation processes.
One of the most important methods is the "flush" to create activation
of the circulatory system . In this case they perform 10 maximum
repetitions for three sets with little rest in between each set. The
performer then goes on to another exercise to address all aspects of
the muscle. His muscle mass can be increased so that limb girth can
increase by up to 3.8 centimeters.
Another method is "cramping", which is done at the end of the above
regime. The performer lifts weight greater than he can lift for the
full range of motion. It is lifted to such an extent so that at
least some movement is possible for a short time in order that it can
bring out the "sick" appearance as seen in conditions of static
circulation. At times, this causes tissue stretching.... In this
method there is shortening and loss of elasticity in the muscles;
therefore, one should always execute some dynamic movements over a
full range of motion after this type of activity.
Choosing the activity for one muscle group is a complicated problem
for the effective training of athletes. In order to activate a
certain muscle group, they use the "cheating" method. When they lift
heavy weights, neighbouring muscle groups come into action to assist
in the execution of this lift. Exercises in such cases are fulfilled
with incorrect technique, as there is a slight change in the basic
structure of the movement. The exercises should be fulfilled with
great resistance and with the ability to repeat it many times.
These methods are good for increasing muscle mass. Comparing this
training with the training of weightlifters, one can see that the
basic difference is in the aspiration of how to increase the
intensity of the changed processes in the muscles, sometimes leading
to a complete change. The basic training of weightlifters (general
training directed toward development of strength without a
significant increase of muscle mass) lies in the conditioned systems
of basic reflexes, which helps insure the best results between the
muscles and internal muscle coordination. Because of this, it is
essential to work as near as possible with the heaviest weights, with
few repetitions each time, and with extended intervals of rest in
between sets. Then, execution of every exercise will be along the
lines of coordination corresponding fully to the movement with
maximum resistance. Also it will help achieve an optimum, but not
delayed fatigue condition in the central nervous system which, in its
own limits, aids in the formation of very fine basic reflexes which
are realized in the cortex.
One can say that the training method used by "culturalists" is
directed towards intensifying the general processes in the muscles,
while training of weightlifters is for establishing corresponding
basic reflexive processes in the central nervous system.
------------
Posted by Dr Tony Shield
I read with interest the recent communications regarding muscle
hypertrophy and whether 'fatigue' acted as a stimulus for it. This
concept is not new (Ingwall, 1976; Rogozkin, 1976). There are also a
number of empirical reasons to believe that the metabolic
consequences of resistance training (and other forms of exercise) may
stimulate hypertrophy. For example, the training practices of many
bodybuilders (moderate resistances, medium to high reps/set,
continuous tension and short inter-set rest periods) appear geared to
maximising metabolic stress rather than muscular tension.
Furthermore, I was surprised by the reticence of many list members to
accept the idea that metabolic stress had a role in mediating muscle
hypertrophy. Thus, despite coming in late on this discussion I wanted
to add my 2 cents worth.
Exercise scientists have been interested, for some years now, in
understanding the mechanisms by which resistance training stimulates
hypertrophy (eg Jones and Rutherford, 1987; Takarada et al., 2000a;
Takarada et al., 2000b; Takarada et al., 2000c) and strength gains
(eg Carey-Smith and Rutherford, 1995; Rooney et al, 1994; Schott et
al., 1995; Shinohara et al., 1998). Particular attention has been
given to the question of whether tension and metabolic stress might
both act to stimulate muscle growth, either in synergy or via
parallel mechanisms.
No one is suggesting that tension is not an important stimulus. We
know that tension, in the form of chronic stretch, can stimulate
muscle growth in the absence of metabolic stress (Antonio and Gonyea,
1993). However, there are a number of reasons to believe that
metabolic stress acts as an additional stimulus, particularly when
resistance training takes the form of medium to high reps with short
rest periods between sets.
Recently those interested in the training of the elderly and frail
have taken up this work because if metabolic stress is a stimulus it
should be possible to stimulate some hypertrophy in populations that
might otherwise not be able to engage in conventional resistance
training because of the heavy loads involved. (This is hardly
a 'trivial' issue if you have osteoporosis or joint degeneration)
The hypothesis that is actually being tested in these studies (Jones
and Rutherford, 1987; Takarada et al., 2000a; Takarada et al., 2000b)
is that the metabolic stress induced by resistance training is a
stimulus for hypertrophy.
Metabolic stress takes the form of substrate depletion (eg. creatine
phosphate breakdown) and the consequent build up of metabolites such
as creatine, Pi, ADP, AMP, H+, lactate or something else! The exact
stimulant is not identified any more clearly than this and it is
probably naive to consider whether any one of these products acts
alone as a stimulus. (Lactic acid gets blamed for almost everything
in exercise science despite a distinct lack of evidence). Clearly,
there is a lot more going on at the cellular level than acidosis! For
example, it has been hypothesised that the occlusion of blood flow in
a contracting muscle and the resulting hypoxia stimulates free
radical production (Takarada et al., 2000b). In addition to causing
tissue damage, there are good reasons to believe that free radicals
may have a role in the regulation of muscle growth (see Takarada et
al., 2000b for the references).
The most convincing evidence that metabolic stress acts as a powerful
stimulant for hypertrophy comes from Takarada et al., (2000b) (as
pointed out previously by Gus Karageorgos). In this study a fairly
conventional moderate-resistance training program (employing ~80% 1
RM) for the elbow flexors was compared to a light-resistance program
(employing ~50% 1 RM) with partial vascular occlusion, a light-
resistance program (employing ~50% 1 RM) without vascular occlusion
and no training (control group). The vascular occlusion (applied via
a blood pressure cuff) ensured that metabolites produced during
exercise were not removed from the muscle, thus maximising metabolic
stress.
After 16 weeks training the changes in muscle CSA for biceps brachii
and brachialis were significantly greater for the 80% 1 RM group and
50%-with-occlusion group than the 50% without occlusion group. No
significant differences were found between the 80% 1 RM group and 50%-
with-occlusion group but the trend was for the 50% with-occlusion
group to exhibit greater hypertrophy, particularly in the brachialis.
Interestingly, the triceps of the occlusion group increased in size
by approximately 13-14% without being trained.
The major limitation of the study is that vascular occlusion may have
had its anabolic effects directly via increasing the metabolite load
or indirectly by raising the level of recruitment necessary to lift
the light loads. However, the former possibility remains plausible
when one considers other findings (Takarada et al., 2000a and 2000c).
Firstly, growth hormone (GH) release has been observed to increase
290 fold over rest levels when extremely light (~20% 1 RM) resistance
training is combined with vascular occlusion. Exercise alone resulted
in negligible changes in GH (Takarada et al., 2000a). Secondly, a
study of young subjects demonstrated that the disuse atrophy caused
by bed rest was prevented by occasional vascular occlusion in the
absence of exercise (Takarada et al., 2000c). Presumably both effects
were mediated by GH's action on IGF-1 which has potent anabolic and
anti-catabolic effects.
It might also pay to consider some observations regarding creatine
that could arguably unify the creatine's ergogenic effects with the
metabolic stress hypothesis. Firstly, creatine induces significant
hypertrophy in unexercised embryonic chick muscle (Ingwall, 1976).
Secondly, creatine appears to stimulate protein synthesis by
increasing MRF4 and myogenin expression in adult humans undergoing
resistance training (Hespel et al., 2001). Finally creatine is a
metabolite produced during high intensity exercise such as resistance
training. One might therefore hypothesise that creatine accumulation
acts to stimulate hypertrophy after resistance training and that
supplementary creatine magnifies this effect.
Regarding some of the valid critiques offered by list members.
1.. It is true that most of the work so far has been carried out on
the relatively untrained elderly. Work is clearly needed on younger
and more highly trained groups. However, in the aforementioned study
the effect of light resistance training without occlusion was almost
zero so it can not be said that the 50% load was sufficient in the
absence of vascular occlusion.
2.. Powerlifters and weightlifters may trigger hypertrophy almost
solely via tension mediated mechanisms while programs employed by
bodybuilders may trigger hypertrophy via a combination of tension and
metabolic stress mechanisms. The recent research shows that those who
employ lighter loads (<50% 1 RM) may still stimulate muscle growth
via maximising the metabolic stress of the workout - even if the
tension levels alone are insufficient.
References
Antonio & Gonyea, (1993); Med. Sci. Sports & Ex. 25(12):1333-1345).
Hespel et al., (2001) J Physiol 15;536(Pt 2):625-33
Ingwall (1976); Supp. Circ. Res 38(5):I115-123
Jones and Rutherford, (1987). J Physiol, 391:1-11
Rogozkin, (1976). Med Sci Sports, 8(1): 1-4
Takarada et al., (2000a). J Appl Physiol, 88: 61-65
Takarada et al., (2000b). J Appl Physiol, 88: 2097-2106
Takarada et al., (2000c). Med Sci Sports Exerc 32(12):2035-9
-------------
Note too, in addition to the latter information I would encourage you
to read some of the work by Tom Incledon, James Krieger, Jerry Telle,
Christian Thibaudeau, Duncan MacDougall and Digby Sale.
-----
Overview of the 3rd Annual SWIS Symposium
by John M. Berardi
www.t-mag.com/nation_articles/186swis.html
Neural Adaptations to Strength Training — Digby Sale, Ph.D.
Dr. Sale is the real deal! This guy is an accomplished researcher
whose work has contributed more to the knowledge of the interaction
between training and the nervous system than anyone else out there.
In addition, Dr. Sale is an interesting speaker and this is rare for
them "academic types." Here are a few things Dr. Sale presented:
• Muscles are engines but they need an engine controller. The central
nervous system is that controller.
• Increased muscle force is developed through two ways:
a. Increased motor unit recruitment — Important up to 50% of maximum
voluntary contraction.
b. Increased motor unit firing rate — Important above 50% of maximum
voluntary contraction.
• Motor neurons and muscle fibers are recruited in order from small
to large.
• During the first rep of an exercise using 50% of 1RM, you recruit
75% of fibers. With each rep you recruit more motor units until
failure. At this point you should have activated 100% of fibers.
• During the first rep of an exercise using 90% of 1RM, you recruit
nearly 100% of max. Each rep after is accomplished through increase
motor unit firing rate.
• Training to failure ensures you will reach nearly 100% of muscle
fibers. If you stop short of failure you may not activate all fibers
and the last few fibers recruited are the biggest ones that grow best.
• Fast contractions require high rates of motor unit firing rate.However, if your intention is to contract quickly but the weight
doesn't move quickly (because it's too heavy), rapid firing rates
will result.
Mechanisms of Muscle Hypertrophy — Dunchan MacDougall, Ph.D.
Like Dr. Sale, Dr. MacDougall is a veteran of the research scene. In
fact, he's so veteran that he's been retired for 2 years. Although I
was totally into his work, the less science savvy were bored to
tears. All this science stuff can be heavy to the uninitiated. It was
sad to see people walking out during this talk. Nearly every slide in
this 90-minute presentation was work that he did himself, making this
presentation a chronical of the man's entire successful career.
Unfortunately, though, the message was lost through the messenger. To
his credit, most of what we know about how weight training creates
bigger muscles can be attributed to 30 years of Dr. MacDougall's
work. Here are the highlights:
• Resistance exercise causes increases in muscle protein synthesis
that peak about 24 hours later and persist for about 36-48 hours.
• Although some people think the anabolic hormone response to
exercise plays a role in muscle growth, this probably isn't true.
Hormones peak immediately after exercise while protein synthesis
peaks much later.
• Training induced increases in protein synthesis occur in starved
animals, in the absence of anabolic hormones, and even in muscle with
no nervous system innervation.
• Increased protein synthesis — manifested as new protein — is added
to the outside of muscle cells, making the cells larger. Likewise,
the splitting of the myofibrils creates a greater number of
myofibrils, all of which are capable of growth.
• Evidence does not support the idea that muscle fiber hyperplasia
occurs in humans.
• Genetics and training play the largest roles in determining how
large a muscle can become.