Muscle Growth/Blood Volume
People often ask me at gyms or at my seminars what is the real key to muscle growth.
My answer often perplexes them. Most expect to hear some “opinion” over sets reps and
workout frequency. But I am a man of science and my gains have come in large part to
my knowledge base. In order to make real world gains it is imperative to have some
understanding of the basic science of what is involved in growing massive muscles. Only
the genetically gifted get by without any kind of knowledge base in the area of muscle
and muscle development. I’m going to walk you through some important facts and
information on the science of building muscle.
Without addressing the training side of the equation for now, my answer to the question,
what is the key to building muscle growth is two fold. Simply put, the answer is blood
volume and cell hydration. But one of these seldom occurs without the other. Nature’s
responses to training stimuli not only give us the answers to how muscles grow, but
nature also gives us hints on we can expound on nature to produce even more muscle
growth. Before we can get into the nitty gritty of that science, lets back track a moment
to review just what a muscle looks like and what structures it is composed of; and as I
mentioned, this is scientific in nature but important for general and specific
understanding of muscles, and muscle growth.
A muscle consists of several components important to understanding growth. The first
two main factors of a muscle cell are the sarcoplasm and the myofibril components. The
sarcoplasm consists of a nucleus of many proteins, enzymes and hormones, and also the
mitochondria, also known as the ATP factory, where muscle energy is made and stored.
The sarcoplasm is considered to be a bath of proteins within which is contained the rest
of the components of the muscle cell. The other main component of the muscle cell is the
myofibril component. Myofibrils house the
fast twitch 2a and 2b fibers you’ve all read
so much about. It is the myofibrillar component of a muscle cell we are most concerned
with when looking at training and the muscle’s cells adaptation to training. The major
contractile proteins of the myofibril are the actin and myosin proteins, which through an
action called “cross bridging” slide across each other to produce contraction. However it
is important to note also that there are more than a dozen other accessory proteins that
exist to participate in muscle action. Ok, so now we know a little about the major players
of the structure of a muscle cell, the sarcoplasm, and the sarcoplasmic reticulum, the
mitochondria, the myofibril, and its main protein components, actin and myosin. Also
surrounding any muscle cell is a proliferation of other cells known as satellite cells.
Satellite cells exist to protect the cell in question. In times of trauma, like that of intense
training satellite cells respond quite specifically to the stimulus, and that is what produces
muscle growth, or what is scientifically known as hypertrophy.
Hypertrophy
The most basic and clinical definition of muscle hypertrophy is, simply an increase in the
individual cross section of a muscle fiber, either the sarcoplasm, or the myofibril, or both.
As strength athletes concerned with understanding muscle growth our focus is mostly on
the myofibril. But the whole scenario of hypertrophy is important to understand to really
know what the process is in muscle growth. When we train intensely for muscle gain,
something in the muscle cell occurs called myofibrillar splitting. This splitting creates a
tiny whole in the muscle cell. Out of that whole leaks key proteins and amino acids, one
known as hydroxyproline. When that happens a whole cascade of biochemical and
endocrine activity occurs. I will cover the endocrine side of this in greater detail below,
when discussing the “pump”. Hormones such as FGF (follicle growth factor, and IGF1,
and IGF2, also leak out of the cell. The IGF hormones send a direct message to the
satellite cells which as you recall surround the cell to protect it. The satellite cells then
fuse with the myofibril creating a larger cell, with an increased cross section, and this is
what is defined as hypertrophy, or muscle growth, as you would have it. Now you know
exactly what is muscle growth, which is muscle cell hypertrophy and now you have a
working understanding of how that process takes place. It always amazes me how many
people confuse hypertrophy with other things like a pump (exercise induced hyperaemia)
which I will get into below, or confuse hypertrophy with a term called protein synthesis.
While all these items are co=related in the matter of muscle growth there are also entirely
distinct functionally even though as we will see, one activity definitely has an effect on
the other.
Protein Synthesis
In order to understand basic biochemical reactions of the body you should know the
meaning of two words, synthesis, and hydrolysis. Synthesis refers to the building up of
one or more items from one or several others, and hydrolysis, refers to the breaking down
of a molecule, usually by an enzyme specific to that molecule. So protein synthesis you
understand is not total body protein. No. Protein synthesis is the build up of body and
muscle protein. Studies prove emphatically that it takes a lot of extra protein, in terms of
build up in the body, to produce muscle growth. This can take place in only two ways
which need not be mutually exclusive. Protein buildup can take place in an anabolic
state, which means systemically the body is building up and retaining nitrogen, as in
puberty, childhood etc, or in an anti-catabolic state. A catabolic state is when the body is
breaking down tissue and is in a negative nitrogen balance. Therefore an anti-catabolic
state is when hormones or other biochemical phenomenon occur to prevent the usual
breakdown of tissue which would otherwise occur. This is much different than the term
anabolic.
In regards to protein synthesis then, increased accumulation of protein only occurs from a
result of net protein synthesis relative to protein breakdown in the body, both in its
current state and over time. Therefore the amount of muscle protein as well is dependant
on a balance between the rate of protein synthesis and protein breakdown. But protein
synthesis in muscle is modulated or tempered if you will, in response to a variety of
stimuli; two of the most important are amino acid availability and exercise. These two
interplay with each other in profound ways and affect the balance of a catabolic or
anabolic state. Protein synthesis is obviously very important to the process of muscle
hypertrophy since the response needed to make a muscle grow involves many proteins
that are within the muscle and need to be available for action at any given time, not just
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as a training response but in recovery response as well where real growing takes place.
While resistance training improves the net balance in muscle stimulating muscle protein
synthesis, nutrient intake and proper timing of nutrient intake obviously is also required
to insure that protein synthesis exceeds the amount of protein breakdown. In fact the
interaction between protein metabolism and any meal consumed in the 24-48 hour period
preceding exercise will determine in large part the impact of diet on muscle hypertrophy.
So the real understanding of what we have so far is that muscle cell hypertrophy takes
place as a specific response to specific training stimuli of at least a certain intensity level.
That is what muscle growth is. But muscle cell hypertrophy is very much dependant on
the net accumulation of protein synthesis in the body and within the muscle cell. So
while training itself produces a stimulus for protein synthesis, this stimulus must also be
met by adequate amounts and proper timing of meals, and of protein intake specifically.
So we now see that muscle cell hypertrophy and protein synthesis are far from the same
thing, but both are very important in the process of gaining muscle.
Endocrine and Biochemical Influences: The Pump
Perhaps the single most important influence on muscle growth is what we call
“The pump” or increased blood volume surrounding working muscles. This is known in
science as exercise induced hyperaemia. At least one study to date, illustrates that blood
flow or lack of sufficient blood flow seems to be a limiting factor for muscle size.
Nutrient delivery, removal of fatigue toxins, and important responses of the body when
training, are all much more efficient in an environment of higher blood volume, again
exercise induced hyperaemia. For example the physiological process of angiogenesis,
which is the growth of new capillaries to feed muscle cells, and enhance oxygen delivery
capacity to muscle cells, only occurs when there is increased demand as through chronic
training protocol over time. Capillary growth occurs around the glycolytic muscle fibers,
(the type 2 fibers) when the stimulus includes increased blood flow, as from training
stimulation, or from metabolic demand, or both. So something as important as increased
capillary capacity and number occurs from chronic training stimulus, yes, but also is
necessitated by a chronic increase in blood flow as well. Increased pump or blood
volume (exercise induced hyperaemia), is a result and dependant upon an integrated
response of more than one important actor. Vasodilation or increased capacity of the
veins and capillaries to expand and handle more blood flow is another example of the
response of the body to training and to higher blood volume demands of training. But
certain hormones and biochemical factors also play key roles. These aren’t exhaustive by
any means but its important to look at the interplay and activity of VEGF (vascular
endothelial growth factor), NO2,( nitric oxide) and IGF1, and the roles they play and
adaptations they have to both training and to their roles in creating and attenuating
exercise induced hyperaemia.
Vascular Endothelial Growth Factor
VEGF is a long term adaptive response to training. It is suggested that the stretching of
skeletal muscle, as in the eccentric phase of lifting is a possible stimulus for VEGF.
VEGF is produced by the muscles and can also be secreted into the circulation. Training
itself produced a 3 to 6 fold increase in VEGF, its receptors and some other dependant
transducers like NO2 synthase ( more on that below). Once VEGF is increased it exerts
its influence in a number of ways but most notably by increasing myoglobin 2.8 fold.
This is important both during training and recovery because myoglobin is the oxygen
carrying protein in muscle tissue, and therefore increased myoglobin improves muscle
oxygenation. The amount of VEGF produced by the muscles from training is also a
direct result of muscle ischemia during training. Ischemia, which means lack of oxygen,
in this case lack of oxygen to working muscles promotes angiogenesis which I mentioned
earlier and myogenesis (creation of new muscle) as well. Since ischemia has a very
positive influence on the amount of VEGF your muscles make, and since ischemia is a
key factor to myogenesis, VEGF can therefore also be thought of as a key contributor to
muscle size. This illustrates the importance of the pump and its effects on muscles and
factors that contribute to growth.
NO2 Nitric Oxide and Nitric Oxide Synthase
NO2 interplays in a myriad of factors which have to do with both increased blood flow
(yes, exercise induced hyperaemia) and muscle growth. It has direct and indirect
influences on both, and many other key players in the muscle growth equation are
dependant upon NO2 in order to exert their influence. For example, increases in
NO2
also lead to increases in VEGF, and all of its benefits discussed above.
What NO2 is exactly is a signal transducing molecule. There are several noticeable
effects of NO2 which again increases in response to training stimuli. NO2 can modify
muscle force, NO2 is also important in the development and control of total body sodium,
and body fluid homeostasis. Levels of NO2 are controlled by enzymes called Nitric
Oxide synthase. Nitric Oxide Synthase, like VEGF, increases 3 to 6 fold from the
stimulus of training. Of paramount importance, is the fact that NO2 is one of the primary
factors in sustaining muscle hyperaemia, so not just getting the pump but keeping it in
order for it to exert all its positive effects including those on muscle growth. So
important is NO2 in this manner, that some of the nitric oxide synthase enzymes are
located within the muscle and some are in the blood vessels themselves. NO2 not only
sustains a muscle pump, but also is responsible for attaining maximal muscle pump.
(muscle hyperaemia) Because No2 is also within blood vessels, the increase in
vasodilatory response to exercise appears not only in the exercised muscles, but
systemically (all through the body) as well. Also in response to training No2 increases its
own levels. Therefore one of the more exciting things about NO2 is its myriad of
activities in both attenuating and maintaining a pump. Again, No2 increases itself as a
training response, dilates blood vessels, and increases glucose uptake. This in turn as
well boosts the pump which is so essential for growth to occur. No2 also has a direct
influence on satellite cell activation to increase muscle growth. So No2 works to increase
the pump and muscle growth in a variety of ways. And not only does No2 boost muscle
growth itself, but builds muscle as well through its effect of elevating other muscle
building hormones like VEGF as I mentioned and just as importantly, IGF1. This is quite
obviously one important element in muscle pump and muscle growth.
IGF1 Insulin like Growth Factor
IGF1 is quite well known in the strength training world. IGF1 as I have already shown
plays a role in satellite cell activation which is what leads to muscle hypertrophy. It also
produces growth hormone like effects by its influence on protein synthesis. IGF1 is found
to be both anabolic and anti-catabolic in this regard. The evidence is fairly clear that
IGF1 promotes muscle hypertrophy via a combined effect on satellite cell activation as
well as protein synthesis accretion in the myofibrils. This is a sort of one/two punch if
you will. This fact of IGF1 influencing both satellite cell activation and muscle protein
build up, suggests a link between IGF1 and NO2. They definitely seem to work in
concert one with the other, in satellite cell activation, muscle repair, and growth.
Research shows that IGF1 is able to enhance blood flow in skeletal muscle through a
NO2 dependant mechanism and that NO2 may be necessary for IGF1 to exert its other
GH like influences, like protein synthesis. Limiting NO2 has a reducing effect on the
capacity of IGF1 in exerting its effects as well. The codependency of all these actors is
very intriguing and as yet not totally understood.
So there we have it. We have reviewed the structure of a muscle cell. We have
explained exactly what is meant by muscle growth and muscle hypertrophy, and
explained the process of muscle hypertrophy as well. Then we discussed protein
synthesis and the important role it plays in these processes. And finally in answering the
question, hey Scott, what is the key to muscle growth, we looked closely and
scientifically and “the pump” and/or the effects of increased blood volume from training
and on training. And as science newbies we now know the scientific term for the pump,
is “exercise induced hyperaemia”
