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Chapter 4 / Kinesiology and Biomechanics
161
Eccentric contractions involve muscle contractions in
which the muscle attachments move farther apart, effectively lengthening the muscle (Fig. 4-9C). Eccentric contractions
are often used to resist gravity or slow down some kind of
movement. For example, slowly lowering a pitcher of water
onto a table utilizes muscle contractions to hold the pitcher’s
weight against gravity while the pitcher is being lowered.
The muscles are contracting, but are also being lengthened.
Extreme Conditions of Muscle Activity
The deterioration of a muscle due to inactivity is called
atrophy. When a muscle is inactive for a long period of
time either by choice or as a result of nerve damage, the
health of the muscle tissue deteriorates. The inactive muscle
requires less energy, so its demand for oxygen and nutrition
decreases. Consequently, circulation to the muscle diminishes, and a downward spiral ensues. The filaments within
the muscle cells deteriorate, the muscle cells get smaller, and
the size and strength of the entire muscle decrease.
Hypertrophy occurs when a muscle becomes enlarged
as a result of forceful and repetitive activity. The number of
muscle cells remains the same, but the length and diameter
of the existing muscle cells increase because the number of
myofilaments within the muscle cell increases.
Tetany is a sustained and forceful muscle contraction
that occurs when nerve impulses arrive at the muscle so frequently that the muscle has no opportunity to relax at all.
Sustained tetany eventually results in muscle fatigue, and the
muscle is unable to hold a contraction.
in opposition to the prime mover. One of the antagonistic
muscles to the triceps brachii is the biceps brachii, which
flexes the elbow.
Skeletal muscles all have one or more antagonists.
Typically located on the opposite side of the bone from
the prime mover, the antagonist lengthens while the prime
mover contracts. Remember, muscles can only pull, not
push.
For movement to occur, antagonists must lengthen while
the prime mover and synergists contract.
Generally, when the nervous system stimulates the
prime mover to contract, it also reflexively inhibits the
antagonist, allowing it to relax and lengthen in order for the
prime mover do its work. Figure 4-10 illustrates this concept
in elbow flexion with the biceps brachii and triceps brachii
muscles.
In addition to maintaining balance in the body, antagonists can slow the action of a prime mover. In Figure 4-10,
for example, the triceps brachii acts as a counterbalance
for the biceps brachii. The act of throwing a bowling ball
is an example of the deltoid muscle acting as an antagonist
to both gravity and some of the pectoralis major muscles,
slowing the downward movement of the entire arm and preventing the arm from dropping like a dead weight.
A more complex example of prime movers and antagonists is the rotator cuff. The rotator cuff is a group of four
muscles that surround the shoulder joint: supraspinatus,
infraspinatus, teres minor, and subscapularis. The rotator
cuff muscles cooperate to move the humerus in a large circle,
in the ROM called circumduction. The individual muscles,
Muscle Movement and
Coordination
Individual muscles cooperate in conjunction with each
other to create movement. Muscles can act as prime movers,
synergists, fixators (also called stabilizers or supports), and
antagonists. Each plays a role in the creation of body movement or stabilization of the body during movement, and any
one muscle can fill any one of the roles at different times,
depending on the movement.
Prime movers , also called agonists, are muscles that
perform most of the intended movement. The main role
of the prime mover is to contract the muscle. For example,
in elbow extension, the triceps brachii muscle is the prime
mover.
the prime mover by contracting at the same time to facilitate
more effective movement. The anconeus muscle is a synergist for triceps brachii in elbow extension. Special synergists
called fixators, also called stabilizers or supports, hold a joint
or another part of the body steady while the prime mover
contracts. If the arm were behind the body during elbow
extension, the teres minor muscle might act as a fixator
to hold the arm back.
Synergists , also known as accessory muscles, help
Antagonists are muscles that move
A
B
Figure 4-10. Biceps brachii muscle in elbow flexion. (A) Elbow
flexion: prime mover, biceps brachii; antagonist, triceps brachii.
(B) Elbow extension: prime mover, triceps brachii; antagonist,
biceps brachii.
162 INTRODUCTION TO MASSAGE THERAPY
however, can be antagonists to each other, as in the case of
the infraspinatus and subscapularis. During medial rotation
of the humerus, the subscapularis is the prime mover and
the infraspinatus is the antagonist. In other words, for the
humerus to move into medial rotation, the infraspinatus
must lengthen while the subscapularis contracts.
Overdeveloping only one of two muscles with antagonistic actions can cause awkward movements and abnormal
body positions. For example, if a body builder overdevelops
the biceps brachii in comparison to the antagonistic triceps
brachii, the arm will remain slightly bent as it hangs down in
a relaxed resting position.
Effects of Exercise on Muscles
Generally, aerobic exercise involves at least 15 minutes of
continuous, moderate muscle activity. Regular aerobic exercise does not increase the size of muscle cells, but it does
increase the number of mitochondria within a muscle cell
and thus the endurance of the muscle. Remember, the mitochondria are the powerhouses of the cell that generate ATP.
When the body experiences regular exercise, muscle cells
store greater amounts of oxygen and ATP to be prepared for
the next period of exercise.
Resistance exercises involve muscles being tasked during physical activity with additional resistance such as
weights or elastic bands. The movements can be static or
dynamic, either preventing or allowing movement to occur.
As a result of resistance activity, the muscle cells increase
their numbers of mitochondria and also increase the number of myofilaments within each muscle cell. The increased
numbers of actin and myosin filaments increases the diameter of the muscle cell and ultimately increases the diameter
and strength of the entire muscle.
Effects of Stretching on
Muscles
People commonly associate exercise and stretching. Stretching
is the elastic elongation of the soft tissues such as muscles,
tendons, fascia, ligaments, and joint capsules. The purpose of
stretching is to lengthen and relax contracted soft tissues to
improve flexibility and mobility and allow the body to rebalance itself. Stretching is most effective when the tissues are
warm, particularly because the tissues are more elastic and
pliable when warm. Conversely, cold muscles and soft tissues
are less elastic, more resistant to stretching, and may be more
prone to injury. Thus, it is more effective and safer to stretch
after having performed some physical activity that increases
circulation to the target muscles. When you recommend clients stretch as a form of self-care, it is important that they
know to warm their muscles and soft tissues via exercise, a
hot pack, shower, or bath before performing their stretches.
Body Movements
The joints allow the body to move when the muscles contract and pull the bones. We have identified the different
types of synovial joints and the types of movements that can
occur at those joints, as well as the different types of muscle
contractions and ways the muscles cooperate to produce
coordinated, balanced body movement. In this section, we
combine the arthrology with the myology to discuss the
many body movements that are created by one or more
joint movements and many different muscles. For instance,
the shoulder area is not only capable of movement at the
glenohumeral joint but is also capable of movements of the
scapula bone. Many body movements, most of them occurring at joints, are illustrated in Table 4-3:
• Flexion—the “bending” movement that decreases
the angle of a joint
• Extension—the “straightening” or “arching” movement that increases the angle of a joint
• Adduction—movement toward the midline of the body
• Abduction—movement away from the midline of
the body
• Rotation—any movement that involves rotation
around an axis
• Circumduction—a combination of abduction,
adduction, extension, and flexion that occurs in
one continuous movement. For example, drawing a
circle in the air while keeping your arm straight is
circumduction of the shoulder.
• Horizontal adduction—movement of the arm toward
the midline of the body in the horizontal plane
• Horizontal abduction—movement of the arm away
from the midline of the body in the horizontal plane
• Elevation—an upward or superior movement of the
scapula or mandible
• Depression—downward or inferior movement of
the scapula or mandible
• Protraction—forward or anterior movement of the
scapula or mandible
• Retraction—posterior or recoiling movement of the
scapula or mandible
• Upward rotation—a rotation of the scapula, moving
the inferior angle of the scapula laterally and superiorly
• Downward rotation—a rotation of the scapula,
moving the inferior angle of the scapula medially
and inferiorly
• Inversion of the foot (supination)—movement of
the sole of the foot toward the midline of the body
• Eversion of the foot (pronation)—movement of the
sole of the foot away from the midline of the body
Chapter 4 / Kinesiology and Biomechanics
Movement Description Movement Description
163
Extension
Spine extension
Increases the angle at a joint
Finger extension
Neck extension Knee extension
Shoulder
Hip extension
extension
Elbow extension Flexion
Spine flexion
Wrist extension Neck flexion
Thumb extension Shoulder flexion
Decreases the angle at a joint
continues on following page
164 INTRODUCTION TO MASSAGE THERAPY
Movement Description Movement Description
Elbow flexion
Lateral flexion
Curves the spine to the left
orto the right
Lateral flexion of
the spine
Wrist flexion Lateral flexion of
the neck
Thumb flexion
Finger flexion
Hip flexion
Finger flexion
Hip flexion
Dorsiflexion
Dorsiflexion
Plantarflexion
Plantarflexion
Hyperextension
Hyperextension of
the spine
Lifts the toes of the foot
superiorly and lowers the heel
Lowers the toes of the foot
and raises the heel
Joint is extended past
anatomical position
Knee flexion Hyperextension of
the neck
continues on following page
Chapter 4 / Kinesiology and Biomechanics
Movement Description Movement Description
165
Pronation
Pronation of the
forearm
Supination
Supination of the
forearm
Abduction
(commonly clarified
as A-B-duction)
Shoulder
abduction
Turns the palm of the hand down
Ankle abduction
Turns the hand palm up Adduction
(commonly clarified
as A-D-duction)
Shoulder
adduction
Takes a structure away from
Wrist adduction
the body or separates fingers
Takes a structure toward the
body or brings fingers together
Wrist abduction Thumb adduction
Thumb abduction Finger adduction
Finger abduction Hip adduction
Hip abduction Ankle adduction
continues on following page
166 INTRODUCTION TO MASSAGE THERAPY
Movement Description Movement Description
Eversion
Eversion
Inversion
Inversion
Lateral deviation
Mandible
Turns the sole of the
Opposition
foot laterally, combining
dorsiflexion and abduction
Turns the sole of the foot
Thumb opposition
Rotation
medially, combining
plantarflexion and adduction
Spine rotation
The body part moves laterally Neck rotation
Movement of the thumb toward
the “pinkie finger”
A twisting or turning of a bone
along its own axis
Circumduction
A fluid circular movement that
combines flexion, extension,
Lateral rotation of
the humerus
abduction and adduction
Shoulder
circumduction
Hip circumduction Medial rotation of
the humerus
Lateral rotation of
the femur
Elevation of the
pelvis
continues on following page
Chapter 4 / Kinesiology and Biomechanics 167
Movement Description Movement Description
Medial rotation of
the femur
Depression
Depression of the
mandible
Depression of the
scapula
Opens the jaw or lowers the
entire scapula
Protraction
Protraction of the
mandible
Protraction of the
scapula
Retraction
Retraction of the
mandible
Moves the mandible or scapula
anteriorly
Moves the mandible or
scapula posteriorly
Elevation
Elevation of the
mandible
Elevation of the
scapula
Inhalation
Inhalation
Closes the jaw or lifts the
entire scapula or femur
Expands and lifts the bony
thorax
Retraction of the
scapula
Exhalation
Exhalation
Contracts and lowers the bony
thorax
168 INTRODUCTION TO MASSAGE THERAPY
• Dorsiflexion—movement of the toes and foot superiorly, toward the body
• Plantarflexion—movement of the toes and foot inferiorly, away from the body
• Lateral flexion—lateral movement of the spine away
from the midline
• Pronation—turning the palm of the hand downward
Central
tendon
• Supination—turning the palm of the hand upward,
as in holding a bowl of soup
Terminology is important when referring to movement. For example, “bending the arm” is an unclear statement because “the arm” includes dozens of bones and joints.
Amore accurate description is flexion of the elbow. Likewise,
Esophageal
hiatus
Aortic
hiatus
“straightening the leg” is a description of knee extension, and
“straightening the back” is the act of exten ding the spine.
Practice using the scientific terms so you are comfortable using
them in professional communication and documentation.
Body Movement Pairs
Functionally, when a muscle concentrically contracts, its
antagonist relaxes. For every movement, there is an antagonistic movement that takes the body in the opposite direction. These body movement pairs are as follows:
• Flexion and extension
• Abduction and adduction
• Lateral flexion to the left and lateral flexion to the right
• Lateral rotation and medial rotation
• Plantarflexion and dorsiflexion
• Inversion and eversion
• Elevation and depression
• Protraction and retraction
• Pronation and supination
• Inhalation and exhalation
Although most people do not realize it, inhalation and
exhalation involve skeletal muscle contractions. When a person inhales normally, or breathes in, the diaphragm muscle
contracts to increase the volume of the chest cavity and pull
Figure 4-11. Diaphragm muscle.
air into the respiratory tract. Exhalation occurs primarily
when the diaphragm muscle relaxes (Fig. 4-11). External and
internal intercostals can expand and contract the rib cage
during heavy breathing, and accessory muscles can also be
involved in these movements.
Knowing these pairs of opposite movements will be
helpful in assessing your client as well as determining the
best course of treatment.
Massage therapists should know the major joints of the
body, the normal movements for each of those joints, and
which muscles provide those movements. (See the special
muscle section and plates at the end of this chapter.) The
dynamic contractions of skeletal muscles are responsible for
creating joint movements, some of which are specific to a
particular joint or bone. Recognizing a client’s limited ROM
in a joint is critical to avoid hurting the client. Knowing
how muscles should be functioning at a particular joint
and whether a client’s pain is triggered by the concentric or
eccentric contraction of a muscle helps you make the initial
assessment and determine subsequent treatment.
Biomechanics studies the mechanics of movement and
how movement is affected by internal and external factors
including gravity, muscle–tendon interactions, neurological input, and physical strain. The basic concepts of biomechanics applied to massage therapy is a practice we call body
mechanics, and it will help you use your body effectively and
efficiently to avoid developing your own pain patterns, injuries, and fatigue. As you learn and practice your strokes and
techniques, monitor your body to make sure that you establish good body movement habits and that you are keeping
H
Chapter 4 / Kinesiology and Biomechanics
169
your body relaxed and comfortable. Body awareness is key.
Ifyou learn how to apply strokes carefully and efficiently
at the beginning of your career, good body mechanics will
become second nature.
Alert
Holding and moving your body inefficiently during
amassage session can lead to fatigue, increased
discomfort, pain, and injury.
Due to the repetitive nature of the work, massage therapists
tend to develop injuries and pain patterns in certain areas
of the body. Not all therapists suffer from pain and injury,
though, and with good body mechanics, body awareness,
and mindful injury prevention, you can enjoy a long and
injury-free massage therapy career.
Components of Good Body Mechanics
Critical components of good body mechanics include efficient structural alignment of your body, proper stance, and
ergonomics. The body should move fluidly, using gravity
and the movement of the whole body to deliver the massage
instead of using the muscles of the shoulders, arms, hands,
fingers, and thumbs. Movement of the body as a whole
improves the fluidity and rhythm of the massage.
Maximizing the amount of pressure and minimizing
your muscular work while giving a massage is very important. Efficient structural alignment will help accomplish both.
When your body is aligned efficiently, your physical work
and the resulting stresses and strains are distributed throughout the body rather than being concentrated on one or two
specific joints. Maintaining efficient structural alignment during a massage can be achieved with the proper stance. The
symmetric and asymmetric stances are stable and balanced,
providing good structural alignment for applying strokes as
well as manipulating clients on the massage table. Stable,
balanced structures are much more efficient than unstable,
unbalanced structures. You can increase your stability by
keeping your center of gravity low with bent knees. You can
increase your balance by holding most of your weight on
one foot while using the other foot for balance.
An equally important concept that can facilitate good
body mechanics is ergonomics, which is the applied science
of adapting the workplace to maximize efficiency and safety.
In massage therapy, we apply ergonomics by ensuring that
your equipment is properly adjusted and easily accessible,
and that the environment is arranged efficiently and with
everyone’s safety in mind.
Efficient Structural Alignment
You need to maintain efficient alignment of your body
to protect your muscles and joints from excessive stress
and strain that can result in pain and injury. Consider the
alignment of the skeleton in a standing posture. The body
is relaxed and comfortable, and the stresses of gravity are
dispersed among the weight-bearing joints. Maintaining a
similar postural alignment while practicing massage is the
first step toward good body mechanics. Keeping your body
relaxed is more comfortable for you as well as the clients.
Using relaxed wrists and hands to apply massage strokes
actually feels more comfortable to clients than using tight,
tense wrists and hands.
Efficient structural alignment consists of keeping the
spine neutral (no flexion or extension), stacking the joints
of the arm delivering the pressure, and stacking the joints
of the leg you put your weight on. The muscles and joints
complicate the task of keeping that structural alignment
because the skeleton has a tendency to move at the joints.
Ittakes some practice to achieve and maintain efficient
structural alignment during massage, but it is well worth
it for the energy it will conserve and the muscle strain
you will avoid. Figure 4-12 illustrates inefficient structural
alignment.
Leaning
Massage therapists have to apply strokes with varying
amounts of pressure as well as lift and manipulate the client’s body. One of the keys to generating power and establishing stability behind your massage work is to use your
body as a rigid structure that takes advantage of gravity
for applying pressure during a massage stroke. Leaning
Figure 4-12. Inefficient structural alignment causes
unnecessary muscle strain for the therapist. (Reprinted with
permission from Frye B. Body Mechanics for Manual Therapists:
A Functional Approach to Self-Care. Philadelphia: Lippincott
Williams & Wilkins, 2010.)
170 INTRODUCTION TO MASSAGE THERAPY
into the stroke uses the weight, strength, and stability
of your whole body to let gravity do some of the work.
Your body uses mostly the postural muscles to maintain
the leaning position, requiring little additional effort or
energy to provide pressure on the client. Pushing, on the
other hand, takes a lot more of your energy because you
use the mechanical strength of your muscles to do the
work.
Leaning allows you to apply appropriate pressure with
minimal stress on your muscles and joints. If you have ever
tried to push a heavy piece of furniture across the floor,
your natural instincts probably led you to lean into the furniture with your arms straight, and your feet in a staggered
position. You do not need to use those kinds of forces for
massage, but the example shows how to maximize the work
you do, with the least physical exertion. Leaning into the client’s body with proper body mechanics creates a more fluid
technique than pushing, is less tiring, and feels better to the
client. Not only does it feel better to clients, it offers them
a sort of safety net by increasing your sensitivity to their
soft tissues. If a client’s body is resisting additional pressure,
sometimes it twitches or jumps or tenses up nearby muscles. When you lean on clients, you are better able to feel
the tissues resist. Therapists who push are less likely to feel
the resistance and are more apt to push beyond the client’s
tolerance, possibly hurting the client. The slow application
of pressure that occurs with a lean allows the tissue to take
more pressure without damage.
Lifting
Massage therapists do a fair amount of lifting during a massage. Draping, undraping, and passive joint movements generally require that you lift different parts of the client’s body,
and it is especially important to use good body mechanics
for lifting. Structural alignment is as important for lifting as
it is for leaning:
• Keep the body part you are lifting close to your body.
• Keep a neutral spine.
• Use your leg muscles to push into the lift rather than
your back or shoulder muscles to move the body part.
• Use both hands to lift when you can.
In the interest of your own well-being, you can politely ask clients to help you by saying, “Could you lift your
leg just a bit so I can slip this sheet underneath it?” Most
clients are more than willing to help, and some even lift
their limbs without a request, just to be helpful. You can
injure yourself lifting clients, regardless of the weight
of the body part, if you use improper body mechanics
(Figure4-13).
Figure 4-13. Improper body mechanics during lifting creates
unnecessary muscle strain on the therapist’s neck and back.
(Reprinted with permission from Frye B. Body Mechanics for
Manual Therapists: A Functional Approach to Self-Care. Philadelphia:
Lippincott Williams & Wilkins, 2010.)
Figure 4-14. Symmetric stance.