Introduction
In 1913, Sir Charles Sherrington wrote that
muscles are synergistic when they "act mechanically in the same direction at the
same joint” or those “which act similarly at two neighboring joints (59).”
Almost a century later, it has been noted by numerous scientists that the
explanation of how the elbow flexors work together (as the definition of synergy
suggests) is extremely complex and, in many
cases, downright unpredictable (73, 13, 20, 12)! Buchanan, along with easily the
top experts in the world regarding the elbow joint, concluded the following in
regards to the muscles which act on this region as well as the movements that
take place therein:
“Suffice it to say that some
kind of computational-predictive-feedback control strategy approach-may be
needed to understand the solutions that the nervous system introduces to handle
what is clearly a highly complex mechanical task (13) “
They propose that the nervous system
literally strategizes each and every movement in a manner that is somewhat
mind-boggling. Thus, it is not enough to relay the actions of the elbow flexors
to you. Instead, we will need to review extensive and extremely complex
literature. I propose a layer-like attack to the subject. Simply put, I will
break down the elbow flexors in a wave-like pattern, or what you might call a
reductionist approach. The goal is to significantly expand your understanding
of this stupendous system.
Overview of Approach
1. Anatomical Overview - Section one will
cover the "basic" actions and anatomical locations of each elbow flexor.
2. Mechanical Terms - To understand how the nervous system recruits varying
muscles, you must understand key Biomechanical terms. I will define them in
section two.
3. Discussion of Muscular Synergies between Elbow Flexors - As bodybuilders,
you need to realize how the elbow flexors interact. Much of this sport is the
enablement of the artist (and that is what a true BB has to be) to target a
specific muscle group.
4. Summary of Synergy - Here we summarize the results found and relay
strategies to promote specified hypertrophy during workout routines.
Additionally, we discuss secondary elbow flexors - Certain muscles can increase
elbow flexion strength, which are themselves not normally considered primary
muscles with this action. Nevertheless, by targeting them, you can
significantly improve your ability to produce torque.
Actions and Anatomy of The
Biceps Brachii
The biceps are, dare I say: a beautiful
muscle. They provide several dimensions to the entire physique. Additionally,
there is essentially no pose which can cover this vital muscle group up.
Several dimensions have been ascribed to their architecture. Such as biceps
height, length, width, density, as well as separation between heads. We will
discuss the science behind those dimensions in our theoretical section. For
now, we focus on anatomical conditions.
We begin with a review from Joe King's and my
own articles on this subject (28, 38 ). The scapula is a triangular bone which
lies on the back of the rib cage. Laterally it has a socket which contains the
head of the humerus. This is known as the shoulder joint. The biceps is a
two-headed muscle and both heads cross the shoulder joint.
1. The short head is also known as the medial head, due to its closer location
to the midline of the body. Its origin (recall that the origin of a muscle
group is the more mobile sect. I.E. when the muscle shortens, it does so from
insertion toward the origin) lies on the coracoid process of the scapula. The
coracoid is a hook-like protrusion which lies laterally and just above your
clavicle. Do you feel that bump? That is where the short head attaches. The
short head tendon passes distally and then blends into the thick gaster or belly
of the muscle. It then continues downward for the length of the humerus.
Finally, its tendon travels past the humerus and inserts on the medial landmark
of the lateral forearm bone, which you know as the radius. The landmark it
inserts on is known as the radial tuberocity. Overall, the short head of the
biceps adds inner thickness to the anterior arm.
2. The long head is also known as the
lateral head, due to its location further away from the midline of the body in
relation to the short head. It originates on the supraglenoid tubercle of the
scapula. Recall that the glenoid fossa is the "socket" which the head of the
humerus forms a joint with. Supra refers to the fact that a protrusion,
directly above the glenoid fossa, can be found on the scapula. Thus, the long
head tendon attaches above the shoulder joint, and therefore crosses it (that is
important!). The tendon then spans out laterally and distally on the humerus.
Consequently, the tendon carves out what is known as the "bicipital
groove," also known as the intertubercular groove (28, 38,51).
It is known as such due to the fact that it is in between two tubercles (which
are protrusions on the humerus where the rotator cuff m. attach, see superficial
muscles of the back part III).
The long head passes distally where the two
heads of the biceps meet for the majority of the length of the humerus. They
are actually separate entities, until their tendons fuse at the end of the
muscle, and finally they both insert into the radial tuberocity. The long head
of the biceps is known for adding outer thickness to the anterior arm, as well
as height or peak.
Key Anatomical Points Which Effect
Actions
1. The bicep’s origin crosses the shoulder
joint. Conclusion: The position of the shoulder joint effects the bicep’s
ability to contract. Secondly, the biceps have actions at the shoulder. Such
consequences make them a "multi-articulate" muscle. Further down in the
article, I will discuss how different shoulder movements effect the biceps.
There is an additional point of interest, however, and that is a multiple joint
muscle has to be innervated by the nervous system in a more complex manner than
a single joint muscle, for the simple fact that it has to control multiple joint
movement (78, 29). As you will see, the biceps are therefore extremely (more like
insanely) complicated, and recruiting of certain aspects of it are indeed
"task-dependent (79, 11)."
2. The insertion point of this muscle is
fixed on a moveable bone (the radius). As a consequence, contraction of the
biceps effects radial movement, and radial movement effect the biceps’ line of
pull! Thus, we are in the presence of a muscle which operates at three
different joints! You can now see why the nervous system has such a tremendous
job.
Actions Discussed
For the above reasons, the actions below may
not always be optimal, depending on the position of the forearm and/or shoulder
joint. Once again, my intentions are to introduce you to these actions now, and
delve into the details later.
1. Flexion at the Elbow - Note that the
muscle fibers of this two-headed muscle are parallel (this has further
implications). When they contract, therefore, they pull the forearm muscles
closer to the humerus, such as in a barbell curl.
2. Supination - Recall that supination is
the process by which the forearm is externally or laterally rotated, such that
the palm of your hand faces upward. It is confirmed that the biceps contribute
tremendously to this movement (50, 58). To understand why, think of a yo-yo. You
begin by winding the contraption up via wrapping the string around its center.
When you release the yo-yo, as the string comes out, it ends out rotating the
yo-yo in a 360 degree motion. Let’s apply this to the radio-ulnar joint. You
realize that the head of the radius fits nicely into the radial notch.
Additionally, the radial tuberocity, which the biceps insert onto, is placed
medially, such that when the radius is pronated (internally rotated), the tendon
of the biceps becomes wound up around the radius like a string on a yo-yo. When
the biceps contract, the tendon pulls on the radius and rotates it back outward
(external rotation).
3. Flexion of The Shoulder Joint -
Basamajian and Delucia found significant activation in the biceps during
shoulder flexion (10); such results have much confirmation (60, 77, 14). An example
of shoulder flexion would be one arm dumbbell front raises.
4. It is fascinating to note that this
muscle actually works as an abductor in cases (61). From Joe King's article we
find that "Abduction means to take a body part away from the midline or center
of the body (40)."
To illustrate my point, let us analyze a
relevant study on the subject. Sakurai et al., in the journal of "Clinical
Orthopedics," conducted the following experiments (61):
Purpose: "Surface electromyography was performed for both heads of the biceps
brachii in 11 healthy men while the muscles were under 30% maximum isometric
shoulder flexion and abduction."
Test: "Electromyographic activity was normalized as a percentage of maximal
muscle contraction during 24 shoulder motions."
Results: "Electromyographic activity was detected in all motions
examined, suggesting that the biceps muscle acts as a flexor and an abductor of
the shoulder."
Interestingly enough, to back the
electromyographic conclusions, they directly tested the power loss and fatigue
in the biceps and found that "Muscle fatigue of the biceps and the deltoid
muscle also was determined at 30% of maximum isometric flexion. All muscles had
significantly decreased mean power frequency and turns count (61)."
5. Studies also suggest that the biceps act
as internal and external rotators of the shoulder joint (61, 10).
6. The long head of the biceps has been
cited as having the ability to provide support to the shoulder joint, in a
similar manner to the anterior rotator cuff muscles (9, 57). For example, Blasier et al. tested numerous muscles’ capabilities to stabilize the
glenohumeral joint. In their experiment, "muscle forces were mechanically
applied to eight shoulder specimens." It was demonstrated that "the long
head of the biceps was found to reduce the subluxation force in certain
positions (9)."
Actions and Anatomy of the
Brachialis
The brachialis is known as the workhorse of
the elbow flexors, due to its high activity level. It lies deep to the biceps
brachii, which makes for some interesting conversation. Firstly, you can see
the muscle distally and on the inside of the arm. It separates the biceps from
the triceps when you look at the arm from the inside, and literally finishes a
straight arm pose.
1. Lateral View of the Arm
2.
Medial View of The Arm
Laterally, the brachialis gives the arm a 3D
look, as seen in the lateral picture above and the anatomical diagram below.
There is a theory which you can understand by carefully viewing the picture: If
you increase the size of the brachialis, it will push the biceps "upwards" and
improve their peak--many feel drastically!
Attachment Points - The deltoid inserts into
the deltoid tuberocity, about one 3rd to halfway down the humerus. There is a
poem, which does not rhyme, that goes like so: "Where Deltoid Ends, Brachialis
Begins." Thus, on the lateral aspect of the humerus, below the deltoid, lies
the origination of the brachialis. It then passes underneath the biceps and
inserts on the Ulnar tuberocity and coracoid process of the same bone.
Points you need to realize as well as
actions:
1. The brachialis does not cross the
shoulder joint and is thus a monoarticulate muscle.
2. Finally, it inserts on an almost unmovable bone. This gives the brachialis
a valuable position among the elbow flexors.
The brachialis acts as an elbow flexor.
Again, due to the fact that it does not have attachment points on the radius, it
does not act as a mover of either internal or external rotation of the forearm,
like the biceps brachii can.
Actions And Anatomy of the
Brachioradialis
The brachioradialis is the freakiest muscle
on the forearm, bar none. It attaches on the humerus and is intimately close to
the lower biceps on the lateral aspect arm. Consequently, if you study an
athlete such as Kevin Levrone, you will notice that these muscles, when fully
developed (and his are certainly that!) give the illusion that your biceps are
lengthened. To put it a better way, it leaves no dead space laterally as the
biceps taper into its tendon. It serves as the great connector between humeral
and forelimb freak.
The brachioradialis originates on the
supracondylar ridge of the humerus, travels all the way down the forearm, and
inserts just proximal (above) the styloid process of the radius. Put your hand
out in front of you with your palms facing downward. Do you see that bump all
the way distal and lateral, near where you would wear a watch? That is the
styloid process of the radius.
Actions - This muscle is an elbow flexor.
However, studies also show it has supination as well as pronation actions.
According to Basamajian and Delucia, it has the capability to supinate the
forearm when it is already pronated, but can only do so to the neutral
position. It can pronate the forearm to the neutral position when it is fully
supinated (10).
Actions And Anatomy of the
Pronator Teres
When performing a hammer curl, you cannot
help but notice the freaky area just under the elbow that spirals down the
forearm. That is the pronator teres. It does much of what the brachioradialis
does, in that it ties in the lower biceps with the forearm (which creates the
illusion of greater biceps length and/or fills in gaps) and provides one of the
freakiest forearm muscles known to man. It originates on the medial epicondyle
(actually just above it) on the humerus, and inserts on the lateral aspect of
the humerus, approximately half way down the shaft.
Actions - This muscle acts as a flexor of the
elbow, as well as in pronation of the forearm (hence its name).
Part Two - Elbow Mechanics
In the following paragraphs, I will explain
to you the main factors which affect the amount of strength produced at the
elbow joint. A few key points to note are as follows:
1. Some muscles have a greater mechanical
advantage at force production than others. Realize that, due to the fact that
we are dealing with flexion, supination, and pronation, these mechanical
advantages will vary.
2. The line of pull changes during elbow
flexion, forearm supination, and pronation for several muscles discussed and,
with it, the mechanical advantages. I will diagram when the advantages are
optimized and when they are at their weakest.
3. Muscles are constructed with notably
different architectures. These architectures effect the amount of force
generated. Such factors are covered below.
4. The architecture of a muscle can also
effect the degree of shortening it is capable of producing, as well as the speed
of shortening.
We begin our discussion with the concept of
"moment."
Moment - In the event that a force causes a
segment to rotate, the product (rotation) is known as a Moment, moment force, or
torque (80). Certain conditions must be met in order for the product "moment" to
be produced. They can be outlined as follows:
Note: Moment and Torque are
interchangeable terms
1. During rotation, a segment moves around
an axis. For our purposes we will say that the axis, which is also known as the
center of rotation, is fixed. For example, your forearm rotates around the axis
produced by the hinge joint of the elbow.
2. The rotation caused needs to be further
looked into and, to do so, I want you to think of a wrench.
If you were to take that wrench and use it to
unscrew a bolt, you would do the following: 1. Attach the wrench to the bolt.
This attachment becomes fixed. 2. Next you apply a force off-center to the
axis of the bolt. In other words, it will do you no good to push the wrench
into the bolt. If you were to do this, you would create no torque. You must
apply the force away from the center of the bolt and, when you do this, you will
produce a Moment.
You need to realize that torque is a measure
of two concepts. The first is force, and the second is known as Moment Arm,
Lever arm, or force arm. Each of those terms is interchangeable. We will use
moment arm here. Thus, when determining the magnitude of a torque, which is how
you would measure elbow flexion strength, you would use the following equation
T = F x MA
Where T = Torque, F = Force, and MA = Moment
arm.
You know that during arm flexion your biceps
contract, and the tensile force that contraction produces is used to move the
forearm closer to the humerus. In your body, therefore, the force is muscular
contraction (that's easy enough). Moment arm is determined by two factors. The
first is rather easy to explain, and it refers to the measured distance away
from the axis to which a force is applied. Below I will show a diagrammatical
illustration of a wrench unscrewing a bolt. The wrench is the long thin line
and the circle represents the axis of rotation. Note that rotation refers to a
circular motion, hence the use of a circle. The arrow pointing to the axis of
rotation does not represent direction; it is simply pointing to the region. The
other two arrows, however, represent the force applied to the wrench "off
center" and the magnitude of that force. Note that the magnitude is represented
by the length of the tail, while the direction is represented by the way the
arrow is pointing.
As you can see, the magnitude of force A,
applied 12 inches away from the axis of rotation, is equal to the magnitude of
force B. With that in mind, we look at the distances. The distance is
represented by a straight line (that's the wrench). Force B is applied 6 inches
away from the axis of rotation and point A is applied 12 inches away from the
axis of rotation. Note that the torque of A is twice that of B. This is due to
the fact that the longer distance the force is applied, the greater the moment
arm. It is for this reason that a longer wrench can give a person a greater
mechanical advantage than a shorter wrench and, additionally, where you apply
the force is directly proportional to the magnitude of the "Moment" or "Moment
Force" produced. The total equation for Moment Arm looks like so:
MA = r X sin ( angle )
Don't worry about the sine function. My main
concern is that you realize that the Moment arm is not only determined by the
distance the force is away from the axis (r), but also the angle which the force
is applied, relative to the straight line distance. Here is the point: If you
apply the force at a 90 degree angle to the line of distance, you will maximize
torque.
To understand, I want you to again think of
what happens when you apply a force to the wrench so that it is pushed directly
into the bolt. Note that you create no torque.
Why is this so? As discussed, a force needs
to be applied off center in order for the segment to rotate around the axis.
This off-center application is maximized at a 90 degree angle of application.
Thus, if you were to apply a force that is less than (acute), or more than
(obtuse) 90 degrees, the Lever Arm or Moment Arm would not be as large as if you
had applied it at a 90 degree angle. This is because not all of the force is
directed into the process of rotating the segment.
Let’s apply this to a muscle:
1.
The further the insertion point is from the axis
of rotation, the greater the distance and, therefore, the greater the moment
arm. This translates to a greater Moment, Moment Force, or Torque.
2.
Think of the arrows above as being fixed, like
the biceps tendon is fixed. The fixed point is the attachment site. Now, as
you move your arm, the "angle of application" changes. Think of the angle of
application changing in a similar manner to how the arrow changed its direction
in the last illustration, as compared to the illustration that was at 90
degrees. Thus, we realize that how much, or how little your forearm is flexed
(in degrees), will directly effect the "size" of the moment arm and, with it,
the magnitude of Torque produced. Dr. Murray and Dr. Delp confirmed this in the
journal of Biomechanics by stating the following:
"Flexion/extension and pronation/supination moment arms of the
brachioradialis, biceps, brachialis, pronator teres, and triceps were calculated
from measurements of tendon displacement and joint angle in two anatomic
specimens and were estimated using a computer model of the elbow joint. The
anatomical measurements revealed that the flexion/extension moment arms varied
by at least 30% over a 95 degrees range of motion. The changes in
flexion/extension moment arm magnitudes with elbow flexion angle were
represented well by the computer model (49)."
Moment Arm Also Effects Joint
Movement
Vital Concepts Outlined:
·
The greater the length of the
moment arm, the greater the force production of a muscle.
·
The smaller the length of the
moment arm, the greater an angle will be over a given distance, relative to the
amount of shortening a muscle will go through. Thus, if muscle A has a longer
moment arm than Muscle B, it will have to shorten more to move a joint through
30 degrees than muscle B does to create the same angle.
The second statement seems confusing, but it
is actually fairly simple. Recall that rotation carves out a circle. A smaller
moment arm would carve out a smaller circle, while a larger moment arm would
carve out a larger circle. Check it out:
The figure represents a diagrammatical scheme
of the arm (upper line) and the forearm (the line at a 90 degree angle to the
arm). The arrows represent muscles and the length of their Moment arms, and the
blue sphere represents the axis, where the joint formed between the humerus and
forearm bones takes place. The smaller arrow has a smaller moment arm, but
notice how it is able to move the forearm through just as large of an angle as
the muscle with the longer moment arm, yet not move as long a distance.
Therefore, we can conclude that a muscle with a longer moment arm is better
suited to produce a larger torque, whereas one with a smaller moment arm can
produce a larger angular movement with less distance. The former is suited for
gross and powerful movements, while the latter is more suited to a greater range
of motion. The elbow requires both of these, and such concepts will help you to
understand why muscles are attached certain ways and what their main function
might be.
The following conclusions of moment arms were
derived from van Zuylen EJ, van Velzen A, van der Gon JJD in 1988, Murray WM,
Delp SL, Buchanan TS in 1995, and Murray WM, Buchanan TS, Delp SL 2000.
Magnitude of Moment arms
1.
The Brachioradialis has the largest.
2. The Biceps Brachii is in second place.
3. The Brachialis comes in third.
4. The Pronator teres has the smallest MA.
As stated, however, moment arms peak at a certain level of elbow flexion (49,
76, 48,55). Here is a breakdown:
Peaks of Moment Arms
1. The brachioradialis peaks at
approximately 90 degrees of elbow flexion (49, 76, 48, 55).
2. The biceps brachii peaks also at approximately 90 degrees of elbow flexion,
and has been shown to vary up to 110 degrees of elbow flexion (49, 76, 48, 55).
Recall that the elbow has been shown to flex at an average of 135-150 degrees of
flexion (30, 31, 62, 63).
3. The brachialis peaks at approximately 100 degrees of flexion, and up to 120
in some individuals (49, 76, 48, 55).
4. The pronator teres peaks at approximately 75-80 degrees (49,
76, 48, 55. )
In conclusion, the Lever arms of the elbow
flexors peak at the top range of motion. For the three larger muscles it peaks
between 90 and 120 degrees, and including all muscles at 75-120 degrees. Thus,
if we only analyze this aspect of torque, the greatest moment is realized at
this range of motion. However, we know that force of contraction is also key to
producing torque. We must therefore analyze each muscle’s force production
capabilities before making absolute conclusions.
Physiological Cross Sectional
Area
As you know, a muscle group can be broken
down into hundreds of thousands of muscle fibers, and the connective tissue
which binds these fibers together, so as to increase their mechanical
capabilities, as well as provide support (look for a biomechanical issue on CT
in the future).
Each cylindrical muscle fiber is, in turn, made of repeating sarcomere units.
Recall that sarcomere units contain the contractile filaments of the muscle
cell, known as actin and myosin.
·
See the following
Articles for discussion on muscle contraction: 1.
Anatomy of a muscle, 2.
All Or None and Whole Muscles, 3.
Pain and Tension
From my Biomechanics article, you understand
that tension can be defined as follows:
While performing the
bench press, the force which your contracting muscles exert against a barbell is
defined as tension, whereas the force which is exerted against the muscle by the
barbell is called the load. –
Quote
Biomechanics And Sport – An
Introductory Viewpoint
(80).
Tension is created when myosin thick
filaments bind to actin thin filaments. The more myosin bound to actin in a
muscle group, the greater the tension produced. Thus, a muscle's ability to
produce tension is related to the number of muscle fibers it contains as well as
the size of those cells (81). Adam Knowlden discussed in "Mobility Training and
the Application of Proper Warm-up for Body Builders" that "The maximal
tensile strength of a muscle (its resistance to pull) is approximately 77 to 80
pounds per square inch."
How, then, can we determine which of the
elbow flexors has the greatest capability to produce force? One way is to
measure what is known as the "Physiological Cross Sectional Area." This is a
very proficient process, but before I explain it to you, it is vital to describe
further the architecture of the current muscles being discussed. There are two
"basic" forms of fiber arrangements in the body.
1. Parallel Arrangement - Here, muscle
fibers run parallel to the long axis of the whole muscle and taper at both ends
into their respective tendons (note: there are two basic forms here: fusiform
and pennate. The former is more parallel than the latter).
Advantages: The fibers in this arrangement
run "almost" the entire length of the muscle. This means that there are several
sarcomere units in one muscle group. Given that all sarcomere units have
similar capacities for shortening, it follows that the more sarcomeres contained
within a muscle group, the greater their capability to shorten. Thus, this type
of muscle would be able to move a joint through a tremendous range of motion, a
concept directly related to its ability to greatly shorten.
2. Pennate - The fiber arrangement here
resembles that of a feather. For example, you might have a tendon which spans
the entire length of the muscle's long axis. Fibers run obliquely along the
long axis. Note below how the cells in this muscle run obliquely to the tendon.
Advantages: The advantage here concerns the
ability to fit more fibers through the length of a muscle than can be fit within
a parallel arrangement, which translates to greater force production. The
disadvantage is that the muscle fibers are shorter, meaning that they have less
sarcomeres in series than a parallel muscle group, and therefore cannot shorten
as much as the parallel group.
Comparison on Speeds - According to Dr. Gregor, when discussing skeletal muscle
mechanics, the length of a muscle fiber is related to how fast a muscle can
shorten. Therefore, a parallel muscle arrangement can shorten faster relative
to a pinnate (32).
In summary, a pennate muscle's strengths are
its ability to generate great amounts of force. However, it cannot shorten as
fast or cause a joint to move through as great a range of motion as a parallel
arranged muscle group.
Cross Sectional Area Discussed
The cross sectional area of a muscle group is
self-explanatory. You begin by finding the thickest aspect of a muscle and cut
right across it in such a way that the slice taken out is perpendicular to the
long axis. This works in a parallel group, but does not comprise the
physiological (functional) aspect of pennate muscle groups. This is due to the
fact that a cross section would only cut through part of the muscle fibers in a
muscle group. Enter the PCSA. Here you cut through an area which goes through
all the fibers in that muscle. Thus, in a pennate arrangement one would end out
slicing through the long axis, as the muscle fibers obliquely insert into the
tendon. When done, you find that pennate muscle groups have larger PSCAs than
do parallel muscle groups.
The PSCA of Each Muscle Group below is
derived from An KN, Hui FC, Morrey BF, Linscheid RL, Chao EY 1981, Lemay MA,
Crago PE 1996, and Murray WM, Buchanan TS, Delp SL 2000 (48, 45, 34):
1.
Brachialis - This pennate muscle group has the
largest physiological cross sectional area at approximately 6.25 cm^2
2. Biceps Brachii - This parallel muscle group is second with a
physiological cross sectional area at approximately 4.5 cm^2
3. Pronator Teres - The PT comes in third at 4.0 cm^2
4. Brachioradialis - This parallel muscle group comes in fourth with a
very small cross sectional area relative to the other muscle groups at 1.4 cm ^2
In summary:
Brachialis - Large PSCA, but 3rd in moment
arm size. Thus, it has a great capacity to generate force, while its moment arm
is adjusted to allow it the capability to move the elbow joint through a large
range of motion. Again, it can produce notable torque due to its large CS and
can move the elbow through an excellent range of motion, but due to its pennate
arrangement cannot shorten as quickly as the biceps.
Biceps Brachii - has the second highest PSCA and the second highest MA. It can
produce notable force and, due to its shortening capacity, can make up for a
lower ability to produce joint movement, as it can shorten greatly due to the
length of its fibers.
The other two muscles as you will see are
meant to support the former.
Length Tension Relationships
A concept discussed in previous articles was
that of the "Length Tension Relationship." In a nutshell, it means that a
muscle reaches a certain length in which contraction is optimal. If it is
stretched too much, the thin filaments are pulled out of the reach of the thick
filaments (labeled c above). Conversely, if the length is too short, there will
be far too much interference (labeled a above).
The length tension relationship in all of the
elbow flexors is easy to remember. They are designed to produce optimal
contractile force when the elbow joint is fully extended, and this force lessens
in a proportional manner to the amount of flexion produced.
Therefore, the optimal moment arms occur at the top range of motion, while the
optimal lengths are reached at the bottom. Such a design makes sense. As the
muscle fatigues on the way up, the mechanical advantage increases. When does
strength peak then? Studies show that it occurs in a compromising manner, when
the moment arm and optimal length are high but not maximized, at approximately
80-90 degrees of pure elbow flexion (39, 19).
You can shock the elbow flexors into growth
and target extra muscle fibers by taking advantage of this area of optimal
strength. The technique, of course, is as follows:
1. Go to failure in a full range of motion.
2. Cheat the weight all the way up and perform barbell curls, from 90 degrees
of elbow flexion all the way up until you have reached failure again.
It is a classic regimen, and the above
clearly explains why you can accomplish this feat. I must, however, emphasize
that the ability for a muscle to develop maximal contractile force is a major
reason for hypertrophy. Eccentric training has been shown in literally endless
studies to produce a greater force of contraction than concentric training (52,
64, 82) and, at the same time, has delivered a greater stimulus for growth and
adaptation to further bouts of hardcore training (22, 72).
The ability of a muscle to contract at 100
percent efficiency, whether eccentrically or concentrically, does not change as
far as the length tension relationship for a concentric or eccentric
contraction. That is, at the bottom range of motion, contractile force is
optimized for any type of tensile force produced by the musculature and, as
discussed, stressing the muscle when it can produce maximal force is extremely
conducive to the stimulation of growth (47).
To this end, we re-analyze the biceps
brachii. Recall that it is a multiarticulate muscle group. As such, movements
at the shoulder joint can enhance or decrease the biceps optimal length. In a
multiarticulate muscle group, when a decrease in angle occurs at two joints at
once, the muscle may accumulate so much slack and shorten to such an extent that
it can barely produce any tension. Such an occurrence is deemed "active
insufficiency." AI occurs in the biceps when both the shoulder and biceps are
flexed simultaneously, meaning that at this stage other elbow flexors would be
relied on rather than the biceps.
With that said, I am going to give you an
amazing tool for enhancing hypertrophy in this muscle group. You see, the
biceps act as a shoulder flexor and, when you contract this muscle, they not
only flex the elbow, but also cause shoulder flexion (60, 77, 14, 61). When
shoulder flexion and elbow flexion occur at the same time, you may produce
momentum, which is good for cheat reps, but you will not get optimal tensile
force in the biceps brachii. Thus, theoretically, if you were to extend the
shoulder joint (extend your arm backward) while simultaneously flexing the
elbow, maximum tensile build up would occur in the target muscle! Are there
studies on this? Indeed there are. In the scientific Journal of Muscle Nerve,
in ‘98 it was found that maximum contraction took place when the shoulder was "hyperextended
(1)." Recall that extension of the shoulder joint occurs when it brings the
humerus to your sides; anything past this is hyperextension. Thus, by moving
the humerus straight backward, past extension, while simultaneously flexing at
the elbow joint, you can increase muscle growth.
How The Elbow Flexors are
Recruited!
I have conducted extensive research on elbow
mechanics. In doing so, I came across a fascinating study conducted by T. S.
Buchanan, G. P. Rovai and W. Z. Rymer in the prestigious Journal of
NeuroPhysiology (73). I found their results summed up elbow flexor research
astoundingly. Thus, we begin this aspect of the article by summarizing their
findings.
The purpose was stated as follows:
"We
studied the patterns of electromyographic (EMG) activity in elbow
muscles of 14 normal human subjects. The activity of five muscles that
act in flexion-extension and forearm supination-pronation was
simultaneously recorded during isometric voluntary torque generation,
in which torques generated in a plane orthogonal to the long axis of
the forearm were voluntarily coupled with torques generated about the
long axis of the forearm (i.e., supination-pronation)."
If that sounded somewhat technical, the point
to understand is that they tested activity levels in several muscles which act
at the elbow. As you recall, differing angels can have profound effects on
activation of any one muscle. They tested this extensively, including analyses
under differing forearm actions such as supination and pronation. What did they
find? I think it will no doubt astound you.
1. Firstly, they discovered that pure
synergy between elbow flexors was rare. They state the following: "we found
that pure synergies in this sense are quite uncommon. For example, we observed that the elbow flexors
biceps brachii and brachialis acted synergically for joint torques generated in
very few directions (73)." When they state, "in this sense," they are
referring to unified synergy (44). This model predicts great amounts of
synergy between all muscle groups so as to simplify the job of the nervous
system (44). It turns out, through numerous studies, that this is far more
complex than was expected when dealing with the elbow flexors (71).
2. How come? Several reasons. For one, you
cannot tell what a muscle's function is by simply reviewing its gross anatomy;
instead, you must rigorously test its function by task.
3. They found that the brachialis was "rather
constant during pronation and supination movements." In other words, the
muscle stayed active, despite forearm position. Why is that the case? Take a
look at its insertion point. The brachialis attaches to the relatively immobile
(although it moves slightly) ulna. Thus, pronation or supination does not
effect its mechanical advantage. It is for this reason that the brachialis is
deemed the workhorse of the elbow flexors (84). However, as you will see, this
does not mean that its activity cannot lower
under various conditions (41), only that it is a mainstay player in the target
motion.
4. They found that "the Biceps acted as a
strong supinator and increased activity with supination resistance (73)."
Recall that the biceps have a strong moment arm for supination. They utilize a
wheel and axel system to cause movement in the forearm joint. If you are
interested in the mechanics of such a system, I describe it in detail in my
second article on Bone Mechanics.
Click Here to review it. Note that as the difficulty of supination
increased, so too did the biceps activation. To this end I recommend various
supination techniques for maximized growth (described shortly).
5. Further into their dissertation it was
reemphasized that "the interactions between elbow flexors is truly complex,
especially for muscles which can flex and supinate (73)." As you recall, the
biceps brachii is a multi-articulate muscle. As such, innervation of it is more
complex than single joint muscles. This is why he stated that not only were the
interactions complex, but an emphasis should be placed on those with more than
one capability! Hang on to that because I will reveal some astonishing facts
latter on this very subject.
6. Buchanen et al. also noted that when the
biceps brachii were most active, the brachialis and brachioradialis were least
active, and vise versa! It was also noted that the brachialis and
brachioradialis actually did show great synergy. Thus, headway began to be
made, and you could hear the excitement in their writings!
"There are three points of interest. First, these plots clearly
demonstrate a positive, near-linear relationship between the BRA and the BRD.
When one muscle is active, the other is active as well, regardless of torque
direction or joint angle...Second, the BIC did not normally share this
relationship. In fact, the BIC was most active when the BRA and BRD were least
active (73)."
We can therefore surmise several key points.
For example, as a sculptor, you have the ability to hone into the brachialis and
brachioradialis at times when the biceps are less active, and can therefore more
selectively "target" certain aspects of your arms for the desired effect.
For more on the artistic aspect of the sport, I would refer you to my colleague,
Mr. Knowlden's genius article entitled:
Monumental Masterpiece - Creating A Cerebral Portrait. That is a
must for any true and serious hypertrophy athlete.
8. In the article referenced above, Adam
made an incredibly true statement. Allow me to quote him:
"The philosophy of shaping a muscle in retrospect to the ideals of this sport is
inherent. But how exactly would one go about this task?
There are multiple ways in which to accomplish this undertaking. But the
fundamental principle to shaping a muscle is a utilizing a variety of angles (42)."
It is exactly this statement which was found
to be the overwhelming case in their study. In fact, they state, and I quote,
"The degree of muscle synergy changes with each
angle, showing that varying tasks, varies activated musculature (73)."
The authors of HYPERplasia have emphasized
this fact, numerous times, and it is due to the overwhelming scientific evidence
to support the claim. For example, Dr. Van Zeulan, one of the world’s most
outstanding experts on motor control, asserts that "The relative activation
of the muscles depends on the elbow angle. Changing the elbow angle
affects the mechanical advantage of different muscles differently. In general,
muscles with the larger mechanical advantage receive the larger input (79)."
Tax et al., after performing extensive testing procedures on the elbow flexors,
made the following statements in regards to task dependency:
"First of all, the concept of
one single activation parameter (total synaptic drive?)
cannot account
for the motor-unit behavior observed
during our experiments: the relative contribution of the two force-grading
mechanisms is different for
different tasks. (69).”
Caldwell, in the European Journal of
Physiology, postulates that, "motor unit recruitment thresholds have
demonstrated the existence of task-specific motor units within the muscles
controlling the elbow (15)." In other words, differing tasks ( i.e. which would
correspond to changing exercises up), can call differing muscles into play, as
well as specific aspects within a single muscle group, ultimately allotting the
athlete an even greater ability to target areas.
Buchanan and colleagues conclude with their
ultimate findings as follows:
”For
virtually every other muscle pair, the degree of coactivation depends on the
particular task at hand. It follows that the concept of synergy is applicable
only under restricted conditions, thereby reducing and perhaps even eliminating
the hypothetical advantage arising from this approach, because a new synergic
relation would have to be defined for virtually every new motor task. This is
similarly stated, although in different terms, by Macpherson (1988). She argues
that although a simple muscle-synergy organization is incomplete, a more robust
task-dependent synergy that is tuned or modified as needed is more likely (73).“
They noted that muscular synergy between the
elbow flexors was "task dependent." It was additionally concluded that they
agree with Macpherson’s conclusion that synergy is modified as needed. My
favorite aspect of his conclusion is that they believe that the nervous system "strategizes."
Thus, rather than stating complete muscular synergy, we can use the term
"strategic synergy!"
Essentially, they find that there is
virtually no position in which equilibrium between all muscle groups is
reached. "If this analysis is correct, the selection of muscles may well be
a computational task in which the nervous system calculates or otherwise
computes precisely the sole set of muscle forces necessary to achieve the
required net torque...Suffice it to say that some kind of
computational-predictive-feedback control strategy approach-may be needed to
understand the solutions that the nervous system introduces to handle what is
clearly a highly complex mechanical task.“ And you thought flexing
your elbow was simple. That is incorrect. Essentially, what bodybuilders have
been stating for years about the ability to target differing aspects of a region
by varying tasks and angles was and always has been correct! It is the latter,
overtly simplistic view which does not agree with experimental evidence (79, 12,
71).
As stated, the above results summarized
numerous findings. In a 1998 edition of Neurophysiology, similar conclusions
were made (71). Buchanan teamed up with several other great scientists by the
names of David P. J. Almdale, Jack L. Lewis, and W. Zev Rymner. They confirmed
task dependent synergies, but also came to further startling conclusions. They
believe that such a system of complexity is best described by the nervous system
(specifically interneurons) "contain(ing) a map of joint torque for a certain
direction and would be accessed by appropriate descending pathways, when such
torque directions were commanded (71)." It is concluded that muscular
synergy can best be described by two mechanisms. The first is that the nervous
system recruits certain muscles depending on their mechanical advantages. It is
remarked that "in this case, each muscle is a single variable in the set of
equations governed by Newton’s laws (71)." I find that astonishing,
however, he also believes that "Of course, there is another possibility: that
the system is redundant and that it is the role of the nervous system to choose
one of a number of possible combinations of muscles that will produce the
desired outcome." Ultimately, it is concluded that a possible combination of
the two may be the factor.
From the above, we can deduce that a very
complex system is involved in coordinating muscular synergies, but when we move
through all the incredible design of the nervous system and its ability to
calculate for each and every task at hand, we do see key patterns arise. As
stated, we know that when the biceps are at their peak activation, the
brachialis and brachioradialis are not. We shall explore this through further
vital literature.
Kulig et al., in the Journal of Medicine and
Science in Sports and Exercise, tested the biceps brachii and the brachialis
during various speeds of contraction, specifically varying the eccentric aspect
of a repetition (41). Each participant performed one protocol with one arm,
while performing a second with the opposite limb. To take the time factor out,
they made sure that each experiment lasted 144 seconds. It is vital to control
the environment to the highest extent in such procedures. Note also that to
correct for any problems, "the right and left arms were selected randomly."
With one arm they lifted the weight in one second concentrically, and lowered it
in an equal time period. However, in the opposite arm, the participants lifted
the weight for one second, but lowered it in five for the eccentric portion of
the repetition. Naturally, the latter protocol performed fewer repetitions.
Results revealed that "The biceps brachii was found to be preferentially
recruited during the fast protocol compared with the brachialis, whereas the
brachialis was found to be preferentially recruited during the slow protocol
(80)."
The reason for their conclusions can be
analyzed several ways. One of which would be that the biceps have a parallel
architecture, compared to the pennate structure of the brachialis. Recall that
the former can shorten faster than the latter. Also recall that the nervous
system recruits elbow flexors based on the task at hand (33, 53, 15). It would
make sense for the nervous system to recruit the parallel group, as opposed to
the pinnate, in a faster protocol. Therefore, by emphasizing slow eccentric
contractions, one can preferentially target the brachialis over the biceps
brachii, and vice versa. To show you my point, Graves et al. studied a range of
people, from young to elderly, and found that those who had a higher reliance on
the biceps brachii, as opposed to the brachialis during elbow flexion, could
accelerate through a given range of motion quicker with the former than the
latter (33), lending more credence to why the nervous system would recruit the
biceps to a greater extent during rapid movements. This study has been
confirmed in other journals. For example, Tax et al., in the Journal of
Experimental Brain Res., found a marked change in motor recruition in the
biceps, even when conditions outside of speed were similar.
They conclude the following: "It
is suggested that the central activation of the alpha and/or gamma motoneurone
pools of m. biceps brachii is different for force tasks and slow movement tasks,
even if the same torques are exerted and/or movements are made
(70)."
The above studies confirm that
elbow flexors are both task dependent, as well as speed of contraction
conscious.
Dr. Basmajian and Dr. Luca performed intense
studies on the elbow flexors, and their patterns of activation also confirmed
Buchanin's observations on muscle synergies. I will summarize these scientists’
findings below:
1. The biceps brachii, when the forearm is
supinated, is activated with or without weight. In fact, it shows the most
activity of all positions when supination is superimposed onto flexion (you flex
and supinate at the same time). This suggests that it is a main player in elbow
flexion and does not play the role of reserve here. However, even when
supination occurs, differing speeds can vary activation, as we have discussed.
2. The Brachialis is active during all elbow
movements; however, I have also shown above that speed of contraction can effect
it, namely during supination movements when the biceps are most active,
corresponding to the time when the brachialis could be lowered in activity for
varying movements.
3. When the forearm is pronated, they found
that the biceps were inactive when no resistance was applied to the forearm.
They were slightly called into play when resistance was applied, however, but
again activity was very low. The nervous system is obviously calling into play
muscles with desired functions and optimal lines of pull. You see, when the
forearm is pronated, the tendon of this muscle is wedged between the radius and
ulna and cannot generate an optimal moment.
It is at a mechanical disadvantage. As you
no doubt may have predicted, the brachioradialis was most active during full
pronation, and of course the brachialis was also extremely active.
4. When the forearm was neutral (i.e. hammer
curl), the biceps were partially activated, while the brachioradialis and
brachialis were highly active. To further understand this, realize that the
biceps act as both a supinator of the forearm and a flexor of the elbow. The
nervous system, therefore, will not fully activate the biceps, as the result
would supinate the forearm rather than maintain a neutral position. In order to
more fully understand this, I feel a discussion on the concept of
compartmentalization is in order.
Studies have confirmed the existence of neuromuscular compartments (83). One
compartment is a "portion" of a muscle which is supplied by a particular nerve
branch. This compartment contains, in many cases, motor units with distinct
functions. Further, the number of muscle fibers in a neuromuscular compartment
varies. Van Zuylen et al. explains by stating that,
"Most muscles are not activated homogeneously; instead
the population of motor units of muscles can be subdivided into several
subpopulations (79)." These scientists further state that:
"Inhomogeneous activation of the population of motor units in a muscle is a
general finding and is not restricted to some multifunctional muscles (79)."
The term inhomogeneous refers to differing activation. In other words, all
muscle fibers are not recruited for one task in a single muscle; rather,
differing tasks can call a specific portion of a muscle into play. Recall that
I stated above that you cannot simply look at a muscles anatomy and predict how
the whole thing will react to a certain action. Van Zuylen confirms this here:
"On the other hand, motor units in muscles are not necessarily activated if
their mechanical action contributes to a prescribed torque. For example, there
are motor units in the m. biceps that are activated during flexion torques, but
not during supination torques." What was explained is extremely vital to
this article and your training. It was noted that certain parts of the muscle
were activated during flexion, but not during supination. This is the concept
of compartmentalization and there is much experimental evidence for it.
Let us review Dr. Chaunad’s studies on the
subject. He analyzed a cat's biceps femoris and found that, "The BF muscle
consists of three neuromuscular compartments: anterior (BFa), middle (BFm) and
posterior (BFp). Each compartment is innervated by a separate nerve branch.” It
was found that each compartment had distinct neuromuscular functions (16).
English and Letbetter studied the gastrocnemius (the lateral large posterior
calf muscle) and found that, "The lateral gastrocnemius is more complex and
contains three distinctly identifiable heads, each of which is a unipennate band
of fibers coursing between a proximally attached aponeurosis of origin and a
distal aponeurosis of insertion (21)."
In the Journal of Physical Therapy, English
et al. summarizes the "partitioning hypothesis" as follows:
1. " The partitioning hypothesis is based on the fact that an individual
muscle is arranged in a more complex array than simply fibers attaching at
aponeuroses, tendons, or bones with a single muscle nerve innervation."
2. They state that neuromuscular compartments
"are distinct subvolumes of a
muscle, each innervated by an individual muscle nerve branch and each containing
motor unit territories with a unique array of physiological attributes."
3. Finally, they assert what many other Scientists have confirmed:
"These
data are complemented by physiological studies, the results from which suggest
that partitions may have functional or task-oriented roles; that is, different
portions of one muscle may be called into play depending on the task demands of
the situation."
Is there evidence for neuromuscular
compartments in the biceps brachii? The answer is yes. First, we need to
consider that the more this muscle is studied, the more complex its actions
become. It doesn't even shorten uniformly! Many have hypothesized that muscles
acted as one large sarcomere unit. In the Journal of Applied Physiology, Dr.
George Pappas and colleagues blew this theory sky high! They actually found
that the biceps shorten "nonuniformely." Results revealed that "mean
shortening was non-uniform along the centerline of the muscle during active
elbow flexion. Centerline shortening in the distal region of the biceps brachii
was significantly less than shortening in the muscle midportion." In other
words, different portions of the muscle shortened at differing rates than others
(34). Segal et al., however, sealed the deal with an amazing finding! Here is
a summary (65):
"Electrophysiological evidence suggests that the human biceps
brachii muscle is organized into functional neuromuscular compartments."
Good point.
"The purpose of this study was to determine whether there was an
anatomical basis for these compartments. Dissection of the biceps revealed both
architectural and nerve branching pattern compartmentalization within the
muscle. Although the biceps brachii is grossly subdivided into long and short
heads, these heads are further subdivided into roughly parallel architectural
compartments. Moreover, these architectural compartments usually receive a
private nerve branch, thus supporting the notion that the human biceps brachii
has neuromuscular compartments."
Thus, there is not only functional evidence,
but now anatomical evidence for neuromuscular compartmentalization in the
biceps. However, there is much more supporting evidence for the above. Brown
et al. conducted a study which was rightfully named, "Further evidence of
functional differentiation within biceps brachii (11)." They studied whether
supination during various phases of flexion could activate different portions of
the muscle. It was found that when the elbow joint was fully extended (or
actually when extended below 90 degrees), that the long head of the biceps was
more activated than the short head during supination movements, and the short
head was more activated when the elbow was flexed past 120 degrees of flexion
than the long head (11). Thus, if you were seeking greater inner biceps
thickness, you would perform resisted supination with the elbow highly flexed,
and if you wanted to target the outer biceps you would perform supination
movements while the elbow was below 90 degrees of flexion (2).
ter Haar Romeny BM, van der Gon JJ, Gielen CC
discovered something truly astonishing. These scientists studied the long head
of the biceps. In doing so, it was revealed that motor units in the lateral
aspect of the muscle were specialized for flexion of the elbow joint, motor
units located medially were activated for supination of the forearm, and motor
units located in the center of the head were specialized for both movements
superimposed on one another (11, 37). Another interesting study, which lends
support to the aforementioned results, was conducted by Dr. Nato and
colleagues. These scientists electrically stimulated different portions of the
short and long head of the biceps. Though not as precise as the nervous system,
they found that in one person electrical stimulation of the long head caused the
action of flexion without supination (54).
The point to be emphasized is that the
nervous system must hone several complex mechanisms for biceps recruition when
the muscle is neutral and still activated. Such a fact corresponds well with
the findings that certain subcategories of motor units are specialists at
various movements. However, I would also point out that several other
mechanisms must take place. For example, certain Pronators of the forearm may
have to resist supination torque during neutral flexion.
5. Dr. Basmajian and Dr. Luca discussed a
few more key findings in elbow flexor coordination.
A. The brachioradialis can mid pronate and
mid supinate. Thus, from a position of full pronation, the BR can supinate to
the point that brings the forearm to a neutral standpoint. Additionally, from a
fully supinated position it can do just the opposite.
B. The pronator teres, when vigorously resisted, assists in pronation torque.
C. Both the brachioradialis as well as the
pronator teres are not normally recruited unless they face resistance. This
leads researchers to believe that both of these muscles serve as "reserves,"
which would explain why the brachioradialis is activated more when the biceps
are not as activated or when vigorously resisted. In fact, I postulate that
this is one of the main reasons you see a synergistic effect between the
brachioradialis and the brachialis. You see, the brachialis is almost always
active, but when its activity lowered, such as in a fast contraction, Basmajian
noted that the brachioradialis actually increased in activity. Thus, during
fast contractions it can actually act as a synergist with the biceps brachii.
These authors believe this is due to stabilizing the elbow joint. However,
Buchanin showed such convincing synergy that I believe it is a combination of
the brachioradialis acting in reserve with the brachialis, and the nervous
system preferably recruiting these two muscles in tandem.
I will conclude this analytical section with
the presentation of one more theory on the multiarticulate Biceps Brachii. It
was written by Dr. Herman and Dr. Flanders in the prestigious Journal of
NeuroScience. They effectively tested the BB, and how it reacted to differing
tasks. According to these authors, results the activity in the muscle was so
complex and so "task-oriented" that it actually violated the size principle.
Recall that this principle states that smaller motor units, such as slow twitch
units are always recruited before fast twitch motor units. They feel, however,
that:
"this elegant functional simplicity of the size principle/common drive
concept is not without drawbacks. When applied to human arm movements it would
predict rigidity within a system whose flexibility is, in fact, amazing. The
directional aspects of everyday reaching movements are manifold, requiring a
versatility that might make it necessary to allow for task-specific,
differential activation of different subunits of the same muscle, resulting in
deviations from a fixed recruitment order (54)." Their overall hypothesis
was varied from the compartmentalization hypothesis. They noted extreme
difficulty in pinpointing a pattern utilized in the biceps muscle. However,
they also noted that differing aspects of the musculature were active for
varying tasks. Here is a summarizing conclusion on their thoughts:
”If differences in mechanical action exist
across units within a muscle, the population of units optimally fit
to produce a required force vector will change with limb position and
force direction during a movement."
The point is this: Muscle fibers with the
greatest mechanical advantage are selectively recruited. Though this violates
the size principle, it is postulated that, overall, it saves energy. Naturally,
that which has the greatest m. advantage would in turn have to use less energy
than a population of motor units which did not have such an advantage.
Overall, I would conclude that it is again a
combination of all the factors mentioned. Indeed, the Nervous system is a
strategizing machine. With every movement you make, it calculates with a
precision that boggles even the most prestigious and qualified scientists. All
agree on this: The movements at the elbow joint are insanely complex, synergies
in some form or another are strategized and, finally, differing portions of a
muscle group can be called into play depending on the task at hand. Thus, you
have the ability to sculpt your physique with an incredible flare!
Strategies
The first thing that needs to be discussed
are split strategies. One made popular by Adam, is the use of targeting
different aspects of a region each workout. For example, in his deltoid
routines, he will work the front delts week one, side week two, and continue on
in a cyclic pattern. The fantastic result is a symmetrical look. Additionally,
the other aspects of the region still get trained, just in a different light.
In utilizing patterns, it appears that the brachialis and the brachioradialis
work together in a synergistic fashion. The pronator teres functions as a
reserve muscle, meaning heavy resistance, as well as strip sets, will bring it
into play. Due to its reserve factor, the brachioradialis will also get worked
during strips. This is one of the reasons these muscle groups get so pumped
when utilizing such a protocol. Thus, we can split the training like so:
Workout A
- Emphasis on Biceps - Such a workout would emphasize supination, superimposed
onto flexion. Additionally, explosive movements will be utilized for an
allotted portion of session A.
Workout B
- Emphasis on Brachialis, Brachioradialis, and Pronator Teres - Within this
framework, one's concentration must be on neutral grip, as well as pronation
style flexion. Additionally, a special emphasis should be placed during a
considerable portion of the workout on eccentric repetitions. As studies have
indicated, even in a supine position, a slow negative protocol will increase
recruition of the brachialis.
The above can be split into alternating
sessions on separate days, or a day can be dedicated solely to the elbow flexors
via an a.m./p.m. session; i.e. a morning emphasis on Biceps, while at night the
emphasis is on the remaining elbow flexors. Consequently, as a reserve muscle,
the p. teres will be placed into the mix with heavy resistance training and any
shocking method which forces you to recruit additional muscle fibers past a
normal set. This would fall into the category of supersets, strip sets,
ascending sets, and what not. Furthermore, when your primary goal is to bring
this muscle group out, you will want to focus your attack with resisted
pronation movements.
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