Gluteals, Extensors and Rotators Intro

Gluteals, Extensors and Rotators

Often Overlooked
Very few weight-resistance trainees devote any direct attention to the muscles that comprise the
area of the gluteal region of the body. Even the most ardent trainees rarely design programs to directly
hit this prominent area. Instead, most trainees prefer to allow the “glutes” to receive inadvertent
attention via those exercises designed for the other areas of the legs. All squatting and pressing
movements activate the gluteal region
and as such, the general view of most
weight-resistance trainees is that these
movements provide sufficient attention
to the gluteal region. Additional
activation of the gluteal area is provided
during the performance of
hamstring exercises with the result
that most trainees assume that specific
attention to the gluteals is not necessary.

Such thinking represents a major
oversight. What is apparently not
realized by those expounding the exuded
philosophy above is that the
muscles that comprise the area of the
hip are extremely powerful and can
be utilized to great advantage in the
development of the legs. As well, for
athletes who are involved in other
sports involving the use of the legs
the development of the gluteal region
could prove to be extremely valuable
in reducing injuries to other parts of the body.

Strong gluteal development also serves to significantly improve performance in many other
sporting activities. The muscles that comprise the region of the hip are called upon during activities
involving running, skating, jumping, cycling, and are directly involved in all floor exercises involving
balance and thrusting actions such as evidence in aerobic, jazz, and ballet dancing. The gluteals are
also highly activated during the throwing events. Many retiring baseball pitchers have announced
their retirement to the loss of power and strength in the legs. A common feature of most power
pitchers is their strong leg development including powerful gluteals.

What should be realized by the weight-training community is that if the gluteals are activated
during other leg exercises then it only naturally follows that specific attention to the gluteals would
provide enhanced growth and development potential of the area which would provide the resultant
benefit of improving performance in other movements. For example, if the “glutes” are called upon
during the execution of the squat or leg press exercises then greater development of the glutes would
allow for increased performance on these exercises which would result in enhanced growth and development
of the legs.

Location and Function
It should be noted that the muscles that comprise the area of the hips work predominately as
hip-joint flexors and extensors they are involved in a number of other actions as well including ab-
duction and medial and external rotation of the thigh.
We shall examine the musculature of the gluteal region which includes not only the more commonly-
known gluteus maximus, medius, and minimus muscles but the piriformis, obturator internus,
and quadratus femoris muscles as well.

Gluteus Maximus (A)
Location
As the name would imply, the gluteus maximus contains the most fibers and represents the largest,
most powerful muscle of the entire body. This muscle forms a large pad over the ischial tuberosity
on the pelvis. It originates from the illium bone located on the hip and from the sacral bone on the
vertebral column, and inserts into the proximal region of the femur on the gluteal tuberosity.
It should be noted that most of the fibers of the gluteus maximus insert along the lateral (outside)
portion of the thigh and nm the entire length of the thigh from the hip-joint to the knee-joint.
This explains why the leg is kept in place and not forced outward during heavy exertion.

Function
The gluteus maximus serves as the major muscle involved in thigh extension at the hip and also
works as a back extensor during the action of hip-joint extension which helps alleviate strain on the
lower back. It also assists in the action of medial rotation of the thigh.

Gluteus Medius (B)
Location
Originates on the illium of the hip and inserts on the greater trochanter of the femur bone of the
thigh.

Function
The function of the gluteus medius is to serve in abduction of the thigh and medial rotation of
the thigh at the hip-joint.

Gluteus Minimus
Location
The most deeply-rooted of the gluteal muscles the gluteus minimus originates on the surface of
the illium and inserts on the greater trochanter of the femur bone of the thigh.

Function
This muscle functions similarly to the gluteus medius in that it is involved in the actions of abduction
and medial rotation of the thigh at the hip-joint.
We shall now examine the location and function of the three frequently overlooked, but highly
active muscles that complete the main muscle of the region of the hip.

Piriformis
Location
Another significant muscle of the region of the hips is the piriformis which sits atop, and serves
to protect the vital sciatic nerve. The sciatic nerve stretches from the dorsal surface of the pelvis, and
was it not for the piriformis, would be exposed to a wide variety of potentially crippling injury risks.
It should be noted however that a small portion of the sciatic nerve remains exposed. This is due to
the fact that the muscles of the region serve to function in the actions of flexion and extension of the
hip.

The above-point would be most noteworthy for those athletes who have chosen to take steroids.
If the steroids are taken by injection in the hip the athlete is in danger of penetrating the sciatic nerve
with the needle. If the sciatic nerve is penetrated, it then becomes deadened with the result being that
the athlete runs a high-risk of becoming paralyzed as ruination of the sciatic nerve destroys the ability
to contract the muscles of the legs.

Function
The piriformis muscle is involved in the actions of outward rotation of the thigh at the hip- joint
and abduction of the thigh during hip-joint flexion. The piriformis also serves to stabilize the hip by
maintaining the position of the head of the femur.

Obturator Internus
Location
Originates on the pelvic surface of the obturator foreman on the pelvis and inserts on the medial
surface of the greater trochanter on the head of the femur.

Function
The obturator internus is involved in the action of lateral rotation of the thigh in the extended
position, and medial rotation of the thigh in the flexed position. It also acts as a stabilizer for the hipjoint.

Quadratus Femoris
Location
This compact flat muscle rests beneath the obturator internus and takes its place of origin on the
ischial tuberosity and inserts into the femur.

Function
The quadratus femoris functions to laterally rotate the thigh.

Lower Back Intro

Lower Back Training

Highly Vulnerable to Injury
The area that comprises the lower back is responsible for more dehabilitating injuries than any
area of the body. In fact, injuries sustained to the region of the lower back ruins more weight-training
careers than the rest of the body combined. Lower back pain and injury are not only prevalent in
weight-resistance training but in everyday “civilian” activity as well. How many times have we heard
about someone bending over to tie a shoelace and then not being able to straighten up? Or how
about the weekend-at-the-cottage syndrome where an unsuspecting victim has reached for a tow line
on the row boat or stretched down to gather some firewood and was left bent-over in agony. Acute
(or chronic) aching-back symptoms plague almost everyone at one time or another in their lives.

Why is it that the lower back is so highly vulnerable to injury?

Poor Mechanical Advantage
The foremost cause of lower back ailment is due to the extremely poor mechanical advantage of
the vertebral column. Whenever a person bends forward during the performance of an activity, from
lifting a bag of groceries to executing the initiation of the concentric contraction phase of the deadlift
exercise, great force is exerted upon a specific area of the vertebral column. The forces that are applied
are: the resistance that is being moved; the weight of the upper torso; and the force of gravity
(9.8 m•s-2). If the combined forces were to be endured by the entire structure of the vertebral column
the risks would be significantly reduced. However, as the forces are focused upon just two or three
vertebrates, the stress upon a small portion of the vertebral column is all too often of sufficient magnitude
to cause injury to the vertebrates, the discs, or the facet joints located on the vertebral column.

Muscles of the Lower Back Weak
Not helping the cause is the fact that the muscles of the region are often underdeveloped and as
a result are too weak to provide sufficient support to the area. Without proper assistance from the
surrounding muscle groups, the bony structure of the vertebral column is forced to endure the
stresses of the forces placed upon the region of the lower back.

Abdominal Muscles Weak
Additional problems arise from the fact that they rarely are the individual’s abdominal muscles
developed to the point where they could provide support for the duress placed upon the lower back.
Poorly-developed abdominals force the vertebral column to endure the forces placed upon the region
of the lower back. Conversely, strong abdominal muscles can provide ample support for the
muscles of the lower back and work in harmony to protect the vulnerable vertebral column from
stress-related injury.

Hamstring Muscles Not Flexible
Another major contributing factor to lower back injury is the lack of fully-stretched and welldeveloped
hamstring muscles. Most people have not done anything to provide for development of
their hamstrings as a result whenever they attempt to bend down to lift something they exert great
force upon the lower back. As the muscles of the lower back are not usually worked in everyday activities
they too are weak. The hamstring muscles insert into the pelvic region. If the hamstrings are
inflexible, they are not able to stretch out and “cushion” the effects of the load. The exerted forces
pull the pelvis downward creating a stretching of the lower back muscles which can cause injuries to
the muscular structure of the region.

When weight-resistance trainees attempt to work their lower backs through bending movements,
the exertion upon the lower back is severely magnified. If the hamstrings have not been worked and
are neither strong nor flexible, and if the abdominal muscles have not been developed, the forces that
are directed into lower back easily overpower the relatively weak muscles of the region. Without support
from the lower back muscles the vertebral column is forced to endure the force of the load.

Poorly-Applied Movement Methodology
The one area of consideration that the athletes have control over is the quality of their movement
methodology; yet, many weight-resistance trainees approach their back training with reckless
abandon. Poor exercise execution represents the single-most preventable cause of lower back ailment.
Poor exercise execution is fostered mainly by the fact that few athletes understand the basis of
vulnerability the lower back is exposed to. If the trainees were fully aware of the dangers involved in
poorly-applied technique in lower back training it is presumed that they would pay more attention to
detail when executing the various lower back exercises. The keys to success in providing for safe and
efficient training of the lower back are:
- Establish and maintain proper posture throughout the lift in order to reduce the stress exerted
upon the lower back;
- Utilize strong neural-impulsing into the muscles of the lower back to protect the vertebral column.

Location and Function
There are two basic sets or groups of spinal muscle that comprise the region of the lower back.
There is a deeply-set group known as the transversospinal muscles and a superficial group known as
the erector spinae muscles. Both muscle groups are covered by a thick sheath of muscle tissue known
as the thoracolumbar fascia which inserts along the origins of the latissimus dorsi. It should be noted
that fascia does not have the flexibility of muscle and as a result is highly-vulnerable to injury during
stress-related actions of poorly-performed exercise execution.

Erector Spinae Muscle Group
The superficial erector spinae muscle group is comprised of three separate (but intertwined)
muscles: iliocostalis (thoracis, and lumborum); longissimus dorsi; and spinalis dorsi. Together these
muscles cover the vast region between the neck to the sacrum which is located on the posterior portion,
and on both sides of the spine. The erector spinae muscles comprise the large ridges that can be
seen running down the length of the mid-line of a well-developed back.

Iliocostalis — Thoracis (A1), Lumborum (A2), Cervicis (A3)
The most laterally located of the erector spinae muscle group the iliocostalis (thoracis and lumborum)
muscle originates on the crest of the ilium and inserts into the nos. These two related muscles
act strongly to rotate the vertebral column.

Longissimus — Dorsi (B1), Cervicis (B2), Capitis (B3)
The longest of the erector spinae muscles, the longissimus dorsi runs almost the full length of
the area of the back. It originates from the most lateral projections of the vertebrae (transverse
processes), and insert in transverse processes which are located superiorly to their location. The longissimus
dorsi is involved in rotation of the spine.

Spinalis (C)
The spinalis muscle is the most medially located muscle of the erector spinae group and, unlike
the semi-spinalis muscle which originated at the mid-way point of the back, travels the entire length
of the mid-line of the back. It originates from the spinous process of the lumbar and thoracic (lower)
regions and insert in the thoracic and cervical vertebrae. The spinalis is involved in rotation of the
spine.

Transversospinal Muscle Group
The deep spinal muscle group derives its name from the location of the fibers which run from
the transverse process to the spinous process of the vertebrae. The transversospinal group is comprised
of the interspinalis (semi-spinalis), intertransversarii, rotatores, and multifidus muscles which
are generally structured in pairs.

Interspinalis (Semispinalis)
The interspinalis or semi-spinalis (as it is sometimes better known)—as its name would imply—
takes its place of origin at about the mid-portion of the vertebral column from the lower thoracic
vertebrae and will generally insert on the fifth to seventh vertebrae which are slightly superior (above)
its location. The interspinalis muscle is involved in the action of extension of both the cervical and.
thoracic vertebrae. This muscle is also involved in the action of rotation of the vertebrae.

Intertransversarii
Takes its place of origin along the vertebral column and attaches to the adjacent vertebrae. This
muscle is involved in extending the vertebral column.

Rotatores
The rotatores muscles originate on the transverse process of one
vertebra and insert into the spinous process of the next superior vertebrae.
This origin and insertion structure of the rotatores muscles
(as their name would imply) provide for a rotating action of the trunk
and are also involved in extension of the vertebral column.

Multifidus (D)
The multifidus muscle has the most fibers and is the thickest and
thus strongest of the transversospinal muscle group. This muscle is
situated in the hollows on either side of the vertebrae. The fibers of
this muscle take their origin from an inferior (lower) vertebra and
insert on superior (usually more than two) vertebrae. The multifidus
muscle aids in the action of rotation of the vertebral column and it
serves to stabilize the vertebral column during lifting actions.

Lying Leg (Knee-joint) Curl

Lying Leg (Knee-joint) Curl

The Lying Leg Curl exercise represents the most fundamental Hamstring movement and offers
opportunity to work the hamstrings with a variety of foot positions. The exercise can be potentially
harmful to the sometimes delicate hamstring muscle group as well as the lower back. Light resistance
should be utilized in effort to reduce the injury risks associated with the lying leg curl movement.

Considerations for Machine Selection
The lying leg curl exercise is performed on a lying leg curl machine. The machine may be either a
combination thigh extension / leg curl machine which as outlines earlier would feature a flat bed, or
a specific lying leg curl lying leg curl machine which could feature either a flat or angled bed. The flat
bed accentuates the upper area of the hamstring muscles as well as the gluteals due to the angle of
pull of the muscles during the movement application. The angled bed allows for greater accentuation
of the hamstrings throughout their range of motion due to the more advantageous angle of pull and
the relationship of the force vector and the gravitation forces experienced during the movement.

The angled bed provides a more natural movement application. Because the semtiendonosis and
the semimembraneosous cross both the knee and the
hip joints the movement application of the leg curl
forces the hips to rise off the flat bed. The resulting
raising up off the bed action exposes the lower back
to potential injury. As well, rising up off the bed reduces
the effectiveness of the exercise due to mechanical
disadvantage of the force vector and its relationship
with gravity.

The angled bed allows for a natural positioning of
the torso with the hips in a slightly raised and thus
natural position for the movement application. The
angled bed allows for contact between the torso and a
solid base of support. The movement application is
performed with the body in a more advantageous position
with respect to the relationship between the
force vector and the gravitational forces.

In addition, the flat bed encourages a lifting of
the head and a rising of the chest off the bed. This
flaw in posture creates an arcing in the back exposing
the lower lumbar region to injury risk. The angled bed
discourages the raising of the head and even if there is
experienced a rising of the chest off the bed, there is a
compensatory base-of-support provided at the hips as
well as a superior angle of application.

Considerations for Feet Displacement
One of the foremost considerations attributed to
proper exercise execution of the leg curl are those
related to feet position and displacement. The feet
should be spaced about 7-9 inches apart (depending
upon the width of the hips), in order to maximize the
effectiveness of the exercise and reduce injury risk. If
the feet are spaced too far apart there will be a severe
reduction in the natural application of the movement
throughout the entire ROM of the hamstring muscles.
In addition wide placements could invoke stress upon
the inner region of the knees.

Conversely, exaggerated close feet placements can
produce great stress upon the spine. In addition,
closed feet placements discourage the activation of
the inner portion of the posterior thigh and encourage
the accentuation of the powerful biceps femoris. The
result is that the hamstrings are not provided with an opportunity for full and even development.
In addition to the considerations given to the displacement of the feet are those areas of concern
related to the basic positions of the feet. The reference here is to:

Feet straight-ahead
This position encourages the incorporation of all three major hamstring muscles.

Heels-in position
This position accentuates the activation of the stronger outer or lateral position of the posterior
region of the thigh, notably the biceps femoris muscle. As outlined earlier the accentuation upon the
powerful biceps femoris muscle discourages a balanced development of the rear thigh.

Heels-out position
This position encourages the involvement of the inner portion of the posterior thigh. The difficulty
experienced with this position is that the weaker region is accentuated during the movement
while the powerful biceps femoris muscles are discouraged from becoming involved in the movement.
This would be an effective position to use if you have been abandoning the inner region and
over-emphasizing the outer portion of the posterior thigh.

It should be noted that the hamstrings as a group are not only called upon to provide support for
the knee joint during the actions of knee-joint flex on and knee-joint extension but to serve to provide
impetus for the action of external rotation of the leg. This action creates the twirling sensation
during the concentric and then eccentric contraction phases of the movement application.

As you go through your set, the heels are encouraged to come inside even more with the result
that increased emphasis is being placed upon the biceps femoris muscle. If you find that the heels are
being forced in too much during the completion of a set (you might want to ask a partner to watch
for the movement of the heel), then simply reduce the weight and focus on maintain the straightahead
position of the feet. It should be noted that when too much resistance is applied, there is a
natural response of the pelvic girdle to rise up from the bed in order to provide for a more optimal
angle-of-pull for the muscles to complete the lift.

This raising of the hips action (hip-joint flexion), is a natural mechanism of the body to alter the
upper attachment of the hamstring muscles so that they can now function more effectively as kneejoint
flexors. This is why the angled bed is more effective in providing for a more natural movement
application. Due to the natural tendency of the pelvic girdle to raise up off the bed during flat-bed
applications of the lying leg curl movement the trainee is exposed to high risk of injury to the lower
lumbar region due to the hyperextended posture of the back.

Dorsi Flexion vs. Plantar Flexion
Another major question that needs to be answered is that of which ankle-joint position should
the trainee assume when applying the leg curl movement? The considerations given to dorsi flexion
applications are that more resistance can be utilized and there is a greater feeling of comfort during
the movement application. The reason for the “appearance” of being able to work with greater loads
is that the calf muscles are greatly activated during the dorsi flexion application.

In addition, the activation of the hip joint also encourages the involvement of the gluteal muscles.
In fact it is very difficult to isolate the neural-impulsing into the hamstring muscles when the
dorsi flexion ankle-joint position is used. Conversely, when plantar flexion applications are utilized,
the emphasis in the hamstring area is more readily realized. This is due to the fact that the calf muscles
are relaxed and not activated nearly as much during the movement application.

As well, due to the plantar flexion position of the ankle-joint the gluteals are discouraged from
taking as much of an active role. It should be noted however, that the trainee must concentrate fully
on directing the neural impulses into the hamstring muscles in order to provide optimal growth and
development opportunity. While the trainee would experience a reduction in the amount of resistance
that would be used, he/she would be comforted by the fact that the burden would be taken up
by the hamstrings and not by the support muscle groups. With reference to the “comfort factor”
there is feeling of a pulling action experienced throughout the posterior region of the thighs and less
of a “squeezing” sensation felt in the calves which offers a feeling of discomfort at the outset. However,
with a little practice, the comfort experienced with the strong activation of the calves will be
realized with the control being exerted with the hamstrings. More significantly, the benefits that will
be realized will far outweigh the considerations for comfort. You may want to experiment with both
ankle-joint positions in order to gain a full appreciation of the sensations attributed to each position.

Considerations for Additional Injury Risks
You will want to be extremely careful not to allow for any “bouncing” to occur at the completion
of the eccentric contraction phase of the movement. The bouncing effect creates a hyperextension
effect upon the knee joint which could lead to serious injury to the popatella ligament located
in the front of the knee. As well, bouncing at the bottom of the eccentric contraction phase of
the movement encourages a resulting lifting of the upper torso off the bed. This is particularly evident
during applications on the flat bed. As the head is raised there is a resulting exaggerated arching
of the back which creates a jamming of the facet joints in the lower lumbar region.

This flaw in exercise execution is frequently illustrated when too much resistance is attempted. If
you cannot perform the movement without rising off the bench if effort to provide required momentum
then reduce the resistance before you injure yourself. It is difficult to avoid rising off the bed
when performing the leg curl exercise on a flat bed machine. This is due to the fact that the hip flexors
are attached to the lumbar vertebrae. As the movement is being performed, the hip flexors pull
with great force upon the femur bones of the upper legs driving them into the bed of the machine
which induces a natural lifting of the head which creates a great arching in the back. You may want to
place a cushion or a towel under the hips to provide a base of support in manner of alleviating the
pressure upon the lower lumbar region.

If during the completion of a set, you notice that you are beginning to rise off the bed, then
simply abort the set, reduce the resistance and pump out a high-rep set of perfectly performed repetitions.
Remember, the hamstrings are a comparatively-sensitive muscle group and as such extreme
care must be taken to avoid injuries to the muscles as well as their connective ligaments and tendons.

Particularly vulnerable is the tiny but prominent popliteal muscle located directly behind the
knee. The popliteal muscle is highly susceptible to injury and once injured (even slightly) it can plague
the trainee for a lifetime. Also at risk are the highly-visible, lateral and medial cruciate ligaments
which provide the support for the knee. These ligaments form the chord-like connections on the
outside and inside portions (respectively), of the posterior region of the knee joint.
In addition, the hamstring muscles themselves can become inflamed and stretched, pulled, or
even tom with poor technique and improper weight selection. Always utilize slow speed-ofcontraction
and highly-synchronized movement applications and use a high degree of common sense
when selecting your resistance on the hamstring curl exercise. You would be well-advised to strive
for the “feel” in the muscle on this exercise one rather than testing yourself on how much weight you
can move.

Summary of Correct Exercise Execution
- Assume a face-down prone position on the leg press machine with the head held to one side or
chin touching the bed. If a straight bed is used use the cheek-to-one-side posture to further discourage
any resulting arching of the back.
- Grip the sides of the bed and make certain the rollers are placed across the Achilles tendon of
the foot. You will want to avoid having the rollers come too far up the calves as this would reduce
the effectiveness of the exercise and could result in knee strain due to the inappropriate angle
of exertion associated with the rollers riding up too high. Conversely you will want to make
sure not to place the rollers too far down on the heels as they could slip off resulting in potential
dangerous alteration in pressure that could damage the knee joints.
- Slowly raise the weight upward by utilizing knee-joint flexion. You will want to be sure to raise
the weight through the muscle’s full ROM before pausing for two counts while squeezing the
weight. You will need to: concentrate fully in order to avoid blasting the weight up too quickly
and bouncing the rollers off the gluteals as rapid movement applications on the concentric contraction
phase of the movement could provoke injury to the knees.
- Once at the fully-extended concentric contraction phase of the movement following the twocount
pause, slowly return the weight to the starting position. You will need to avoid the general
pitfall of allowing the weight to return too quickly by utilizing strong neural impulsing to provide
well-controlled muscular contractions.

Keys to the Lift
- Make certain to keep the bead down throughout the movement application
- Utilize slow speed-of-contraction applications
- Exercise caution in selecting the resistance to be used in this movement

Hamstrings Intro

Hamstrings

Often Overlooked
The posterior muscles of the thigh are
often overlooked by many weight-training
enthusiasts. Even those trainees who devote
additional time to their leg training so
as to include isolation work on their quadriceps,
frequently neglect to include hamstring
movements into their leg exercise
portfolio. It seems that many weightresistance
trainees apply the “out-of-sightout-
of-mind” adage to their leg training. It
is much more encouraging to work on the
quadriceps where the deep cuts and crevices
can be readily admired. The hamstrings
are not as visible, and thus they require
more diligence on the part of the trainee to
provide proper development. From a tangible
perspective, the “hams” are not called
upon as prominently as the quads in performing
various athletic movements.

However, neglecting the hamstrings
reduces the trainee’s ability to fully develop
their legs. No trainee would ever think of
building only their biceps and not devoting
any attention to their triceps why is it then
that it can be assumed that proper and thorough
leg development can be accomplished
by placing emphasis on only the
anterior thigh and leaving the posterior
thigh untouched?

The benefits of providing for balanced
development of the legs can be realized
from an injury reduction perspective as
well. How many times have you heard of an athlete pulling their hamstrings? In fact I would be willing
to bet that the first mention you heard of the hamstring muscles (outside of the gym), was in reference
to an injury. Sprinters for example, who have built up their quadriceps through their running,
undergo the risk of pulling their weaker hamstrings due to the imbalance of strength.

While running encourages the development of the quadriceps it should be noted that the hamstrings
work in synergy with the quads. If the frontal thigh muscles are developed well beyond the
level of the posterior thigh muscles the posterior muscles become highly- vulnerable to injury risk.
From all perspectives, it makes sense to offer equal devotion to both the anterior and posterior regions
of the thigh.

Location and Function
The posterior region of the thigh is comprised of three main muscles all of which cover both the
knee and the hip joints. Since the hamstrings cross two joints they provide a function at each of
those joints. They serve as extensor of the thigh at the hip joint and flexors of the lower leg at the
knee joint.

Semitendinosus (A)
Location
Originates from the ischial tuberosity of the posterior hip and inserts on the medial surface of
the superior portion of the tibia at the knee.

Function
In addition to providing for hip joint extension and knee joint flexion, the semitendonosous is
also involved in medial rotation of the tibia.

Semimembranosus (B)
Location
Originates on the ischial tuberosity of the posterior hip and inserts on the posterior portion of
the medial condyle of the tibia at the knee joint.

Function
The Semimembranosus is also involved in medial rotation of the tibia.

Biceps Femoris (C)
Location
The biceps femoris of the posterior thigh is similarly constructed to the biceps femoris of the anterior
upper arm in that the muscle has two distinct (long and short), heads. The long head originates
on the ischial tuberosity where it shares a common tendon with the semitendonosous which crosses
at the hip joint. The short head originates from the lateral edge of the linea aspera alongside the femur
bone of the upper leg and the supracondyle region located on the proximal (inside) area of the
femur. Both the long and short heads of the biceps femoris combine via a single tendon and insert
on the head of the fibula of the lower leg.

Function
Both the long and short heads are involved in the action of leg flexion at the knee joint and are
also involved in the lateral rotation of the leg during knee flexion. It should be noted that because the
short head of the biceps femoris does not cross the hip joint it serves no function in hip joint activity.

Muscle Activation
Unlike the quadriceps muscles, the hamstring muscle group is not readily called upon during
many events involving physical activity. While the “quads” are called into action during such activities
as the ascending and descending of stairs or in the relatively simple task of walking, the hamstrings
relatively speaking lay mostly dormant with the result being that the muscles of the posterior thigh
are not nearly as developed as the quadriceps. As a consequence of their reduced activity, whenever
the hamstrings are called upon during movements requiring their high activation, they become correspondingly
highly susceptible to injury. It is important to realize the level of caution that must be
applied to hamstring training in order to stimulate growth and development while at the same time
reducing the risk of injury to this highly-vulnerable muscle group. As a manner of general approach,
the trainee would be well advised to work with light resistance and to utilize slow speed-of- contraction
movement applications featuring full range-of-motion contractions. In this report we will be
analyzing three hamstring movements. Two movements will feature knee joint flexion (lying and
standing leg curls) and one will highlight a stretching action of the posterior thigh (deadlift).

Leg (Knee-joint) Extension

Leg (Knee-joint) Extension

Introduction
Performing the power movements of the leg exercise inventory (the power movements will be
covered in detail later in this section), will develop both the posterior and anterior regions of the
thighs. However, in order to create clear definition and separation of the quadriceps muscles, specific
attention must be devoted to the area. The most effective manner in which to isolate the quadriceps
is to perform the thigh (knee) extension exercise. It should be noted that there are a number of power
type movements that provide opportunity to build rippling quadriceps including front squats.

Considerations for Machine Selection
The thigh extension exercise is performed on a leg extension machine. There are two basic variations
of the leg extension machine:

- Combination thigh-extension and thigh-curl machine
- Specific leg extension machine.

Because the combination thigh extension/thigh curl machine was designed to accommodate exercises
for both the quadriceps and the hamstrings, the bed is flat. The specific thigh extension machine
allows for either a flat position of the seat or an angled seat. Some machines feature multi-angle
capability which allows for a variation in frontal thigh accentuation.

The flat bed, while allowing accentuation of the entire frontal thigh really emphasizes the lower
region of the frontal thigh. The angled bed also provides accentuation of the entire frontal thigh but
allows for facilitated accentuation of the upper region. Of the two machines, the specific thigh exten28
sion machine can be used to greater
advantage than the combination machine
because of the angled bed. As
well, the specific leg extension machine
provides a back rest which allows
for facilitated maintenance of
desired posture. Some machines offer
a single-leg application of the movement
for even greater isolation.

Considerations for Foot
Positions
This particular movement can be
applied with a variety of foot placements
(wide, narrow, closed) and four
ankle-joint positions (inversion, eversion,
and plantar and dorsi flexion).
Each specific approach to the thigh
(knee-joint) extension exercise will
provide specific accentuation upon
the quadriceps muscle group. Narrow
and closed stances stimulate the outer
region of the frontal thigh while the
wide foot placement would encourage
activation of the inner portion of the
frontal thigh. In addition, the eversion
position of the ankle-joint would
provide high activation of the vastus
medialis located on the inner anterior
thigh while the inversion position of
the ankle-joint would provide stimulation
of the outer portion of the anterior
thigh. The plantar and dorsi
flexion positions would stimulate the
middle portion of the anterior thigh.
The three main foot positions
that can be applied during this exercise
in order to accentuate the various
areas of the frontal upper leg (thigh)
are as follows:

Toes straight-ahead position
This position is considered to provide for a general
emphasis to be applied to the four quadriceps muscles.
Though it should be noted that the vastus intermedius
bears the major brunt of the exertion here which results
in the rectus femoris (the large muscle in the middle of
the frontal upper leg) to be accentuated.

Toes turned-in position
This position allows for an accentuation of the vastus
lateralis which provides for that sweeping outerregion
that is so impressive in frontal thigh development.

Toes turned-out position
This position allows for the accentuation of the
medial (inner) region of the frontal upper leg. The vastus
medialis (the large bulging muscle on the inner portion of
the lower region of the frontal thigh) is greatly accentuated
during the toes turned-out placement. Additional
emphasis can be provided to the inner portion of the
inner thigh by rotating the ankle joint outward.

You may want to experiment with the various foot
positions and placements as you continue through your
program but for purposes of a general frontal thigh application
the beginning weight training student would
best be served with a toes straight-ahead position.

Considerations for Feet Displacement and
Dorsi and Plantar Flexion
The feet should be placed about 6-8 inches apart
(depending upon the width of the hips) in order to provide
optimum growth and development potential. Wider
feet placements reduce the natural range-of-motion and
encourage breakdowns in technique such as rocking forward
and backward which encourages a drooping of the
head response which induces the back into a rounded posture which could lead to lower back injury.
Extremely close feet placements can invoke strain upon the spine. Close placements also discourage
the involvement of the vastus media1is during the movement.

There is also much discussion concerning the position of the feet with respect to either dorsal or
plantar flexion. Dorsal flexion (toes pointed up), encourages an increase in tension during the
movement application which allows for greater accentuation to be applied upon the vastus interme-
dius which promotes the accentuation of the rectus femoris. This response creates the deep crevices
and distinct separation in the muscles of the frontal thigh. The action of dorsal flexion however encourages
the upper torso to come forward which reduces the range-of-motion and creates stress
upon the lower back.

The tendency with dorsal flexion applications is to apply herky-jerky movement applications with
an exaggerated rocking motion which reduces the effectiveness of the exercise and could lead to lower
back injury.

Plantar flexion applications (toes pointed straight ahead) encourage full range-of-motion applications
but they also promote increased speed-of-contraction applications which can invoke serious
knee injuries during the concentric contraction phase of the movement. Particularly vulnerable is the
patella ligament which can be easily strained if the movement is not highly-controlled.

Summary of Correct Exercise Execution
- Assuming the use of a specific leg extension machine position yourself upon the seat so that the
edge of the seat is fitted snugly into the bend of the knees.
- Place the insteps under the rollers about 6-8 inches apart making certain that the rollers do not
come up on to the shins. If the rollers come up too high they will alter the force vector thus reducing
the effectiveness of the exercise. Conversely you will want to make certain that the rollers
are not placed too low near the toes where they might slip off during the movement creating a
pressure differential that could invoke injuries to the knees and to the lower back.
- Grip the handles at the side of the seat and straighten the arms and lift the chin up and thrust the
chest forward in order to assume the proper posture to allow for the safe, efficient movement
application. Make certain that you establish contact with the back rest and if a cushion is available
place it at the area of your lower back in order to provide maximum stability. Note: If a combination
leg extension/leg curl machine is being used you will want to make certain to place the
end of the bed behind your knees and lean back slightly (about 35 degrees). By leaning back you
are able to allow for a full range-of-motion application and you will reduce the stress upon the
lower lumbar region. You will need to grip the side of the bench with a fully extended arm position
in order to keep provide for the desired head-up posture. You will also want to avoid the
tendency to lean back too far in the starting position as this will reduce the effectiveness of the
exercise. As well, you will need to concentrate fully on avoiding the natural urge to lean back
during the application of the movement in effort to provide momentum to the lift.
- With either the specific or combination machine usages, you will want to keep your head held in
the erect position. If the head is allowed to droop during the movement it will create a resulting
rounding of the back posture. A rounded posture greatly reduces the range-of- motion capability
and places adds exertion upon the lower spine which could easily result in injury.
- Once in the correct position slowly raise the weight by extending at the knees. You will want to
resist the urge to snap the weight up into the fu11y-extended position. It is imperative to extend
slowly in order to avoid the dangerous snapping action which could. produce serious injury to
the patella ligament in the knees as well as to the lower back. Some trainers advocate the concept
of not fully extending in the finish position in order to reduce the risk of knee and back injuries.
However, it is felt here that a properly performed extension will allow for an enhanced growth
and development benefit associated with a full range-of-motion contraction while allowing for a
safe movement application.
- Once at the fully-extended concentric contraction position bold the resistance for two counts in
order to allow for the impulse to run the entire length of the frontal thigh and then slowly lower
the weight to the starting position.
- You will want to concentrate on maintaining correct posture during the eccentric contraction
phase of the movement in order to avoid “bouncing” into the subsequent concentric contraction.
The bouncing action encourages the body to bend forward which severely reduces the
range-of-motion and could lead to lower back injury. As well, by lowering the weight slowly you
are more easily able to avert the tendency of raising off the seat in effort to provide body-weight
momentum into the following concentric contraction.
- You will need to concentrate strongly in order to maximize neural-impulse activity throughout
the eccentric contraction phases of the movement. Lactic acid builds up readily during this exercise
and the natural tendency is to yield to the pain and come only partially through the ROM before
attempting to blast the weight back up. This aborted approach to the movement application
creates a herky-jerky movement application that can invoke injuries to the lower back as well as
the knees.

Keys to the Lift
- Keep the head up and the back straight throughout both the concentric and eccentric contraction
phases of the exercise.
- Utilize slow movement applications and avoid “snapping out” in order to reduce the risk of injury
to the knees and to the lower back.
- Concentrate fully on avoiding the natural tendency to “bounce” into the concentric contraction.

Single Leg Variation
A variation of the thigh (knee-joint) extension movement is the single leg application. The single
leg approach provides even greater emphasis on the quadriceps. However, it is recommended that
beginning weight-training enthusiasts perfect the technique of the conventional two-legged version
of the exercise before implementing the single leg application in order to avoid the common flaws in
technique that are accentuated during the performance of the single leg exercise.
Flaws in Execution

- Dropping the head and leaning forward during the execution of the concentric contraction.
- Rocking back and forth during the movement application
- Performing the movement with herky-jerky movement applications
- Not locking out at the completion of the concentric contraction phase
- Bouncing at the bottom of the eccentric contraction phase.
- Using rapid-fire speed-of-contraction during the movement application.

It should be noted however that these flaws in technique can be easily averted with a little experience
with the thigh (knee-joint) extension exercise and should not be overlooked entirely. In fact
the practiced trainee can apply more
ly-facilitated perfected technique in the single
leg version due to increased accentuation
and more readily-facilitated range-of
motion applications.