NASM essentials of sports performance training
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NASM essentials of sports performance training


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the head and
trunk, and radioulnar pronation and supination (4,5,8) (Fig. 2.5). The transverse plane motion
of the foot is termed abduction (toes pointing outward, externally rotated) and adduction (toes
pointing inward, internally rotated) (5). Examples of transverse plane movements include cable
rotations, turning lunges, throwing a ball, and swinging a bat (Table 2.1).
COMBINED JOINT MOTIONS
During athletic movements, the body must maintain its center of gravity aligned over a con-
stantly changing base of support. If a change in alignment occurs at one joint, changes in align-
ment of other joints must occur. For example, when an athlete stands and rotates his femur in-
ward, then outward, you will notice obligatory effects from the subtalar joint to the pelvis. When
the femur is turned inward (femoral internal rotation), total kinetic chain pronation occurs at the
subtalar joint, knee joint, and the lumbo-pelvic-hip complex. When the femur is turned outward
(femoral external rotation), total kinetic chain supination occurs. 
TABLE 2.1
Examples of Planes of Motion, Motions and Axes
Plane Motion Axis Example
Sagittal Flexion/Extension Coronal \u2022 Bicep Curls
\u2022 Tricep Pushdowns
\u2022 Squats 
\u2022 Front Lunges
\u2022 Calf Raises
\u2022 Walking
\u2022 Running
\u2022 Vertical Jumping
\u2022 Climbing Stairs
Frontal Adduction/Abduction Anterior-Posterior \u2022 Side Lateral Raises
Lateral Flexion \u2022 Side Lunges
Eversion/Inversion \u2022 Side Shuffling
Transverse Internal/External Longitudinal \u2022 Cable Rotations
Rotation \u2022 Turning Lunges
Left/Right Spinal Rotation \u2022 Throwing
Horizontal Adduction/ \u2022 Golfing
Abduction \u2022 Swinging a Bat
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18 CHAPTER 2
A B C D
E F G H
I J
K L
FIGURE 2.3 FLEXION/EXTENSION MOVEMENTS. (A) Shoulder flexion. (B) Shoulder extension. (C) Hip flexion. (D) Hip extension.
(E) Spinal flexion. (F) Spinal extension. (G) Elbow flexion. (H) Elbow extension. (I) Knee flexion. (J) Knee extension. (K) Plantar flexion.
(L) Dorsiflexion.
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INTRODUCTION TO HUMAN MOVEMENT SCIENCE 19
A
C
E
B
D
F
FIGURE 2.4 ADDUCTION/ABDUCTION MOVEMENTS. (A) Hip abduction. (B) Hip adduction. (C) Shoulder
abduction. (D) Shoulder adduction. (E) Eversion. (F) Inversion.
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20 CHAPTER 2
A B C
D E
F G
FIGURE 2.5 ROTATIONAL MOVEMENTS. (A) Spinal rotation. (B) Radioulnar supination. (C) Radioulnar pronation.
(D) Shoulder internal rotation. (E) Shoulder external rotation. (F) Hip internal rotation. (G) Hip external rotation.
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Even though a joint has a predominant plane of movement, all freely moveable joints can
display some movement in all three planes of motion. Functional, multiplanar biomechanics can
be simplified into pronation and supination (10); the key word being simplified. In reality,
pronation is a multiplanar, synchronized joint motion that occurs with eccentric muscle func-
tion. Thus, supination is also a multiplanar, synchronized joint motion that occurs with concen-
tric muscle function (Table 2.2).
INTRODUCTION TO HUMAN MOVEMENT SCIENCE 21
TABLE 2.2
Pronation and Supination
During Pronation
The foot Dorsiflexes, everts, abducts
The ankle Dorsiflexes, everts, abducts
The knee Flexes, adducts, internally rotates
The hip Flexes, adducts, internally rotates
During Supination
The foot Plantar flexes, inverts, adducts
The ankle Plantar flexes, inverts, adducts
The knee Extends, abducts, externally rotates
The hip Extends, abducts, externally rotates
The gait cycle will be used to briefly describe functional biomechanics to show the interde-
pendence of joint and muscle actions on each other (11,12). During the initial contact phase of
gait, the subtalar joint pronates creating obligatory internal rotation of the tibia, femur, and
pelvis. At midstance, the subtalar joint supinates leading to obligatory external rotation of the
tibia, femur, and pelvis. The Sports Performance Professional should remember that these link-
ages are bidirectional. For example, pelvic motion can create lower extremity motion and lower
extremity motion can create pelvic motion (10,13).
Poor control of pronation decreases the ability to eccentrically decelerate multisegmental mo-
tion that can lead to muscle imbalances, joint dysfunction, and injury. Poor production of supina-
tion decreases the ability of the HMS to concentrically produce the appropriate force for push-off
that can lead to synergistic dominance. During functional movement patterns, almost every muscle
has the same synergistic function: to eccentrically decelerate pronation or to concentrically acceler-
ate supination. When an articular structure is out of alignment, abnormal distorting forces are
placed on the articular surfaces. Poor alignment also changes the mechanical function of muscle
and force-couple relationships of all of the muscles that cross that joint. This leads to altered
movement patterns, altered reciprocal inhibition, synergistic dominance, and ultimately, decreased
neuromuscular efficiency\u2014concepts that will be developed throughout this book.
MUSCLE ACTIONS
Muscles produce tension through a variety of means to effectively manipulate gravity, ground reac-
tion forces, momentum, and external resistance. There are three different muscle actions (Table 2.3):
\u2022 Eccentric
\u2022 Isometric
\u2022 Concentric 
TABLE 2.3
Muscle Action Spectrum
Concentric Developing tension while a muscle is
shortening; when developed tension
overcomes resistive force
Eccentric Developing tension while a muscle is
lengthening; when resistive force overcomes
developed tension
Isometric When the contractile force is equal to the
resistive force
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22 CHAPTER 2
Hip
adductors
Hip
abductors
IT band 
A
Multifidus
Transverse
abdominus
B
Supraspinatus
Infraspinatus
Teres major
Teres minor
C FIGURE 2.6 Examples of Dynamic Stabilization.
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INTRODUCTION TO HUMAN MOVEMENT SCIENCE 23
ECCENTRIC
An eccentric contraction occurs when a muscle develops tension while lengthening; the muscle
lengthens, because the contractile force is less than the resistive force. The overall tension within
the muscle is less than the external forces trying to lengthen the muscle. During resistance train-
ing, an eccentric muscle action is also known as \u201ca negative.\u201d This occurs during the lowering
phase of any resistance exercise. During integrated resistance training, the eccentric action exerted
by the muscle(s) prevents the weight/resistance/implement from accelerating downward due to
gravitational force.
In athletic activities, muscles work as much eccentrically as they do concentrically or iso-
metrically (14,15). Eccentrically, the muscles must decelerate or reduce the forces acting on the
body (or force reduction). This is a critical aspect of all forms of athletic movement because the
weight of the body must be decelerated and then stabilized in order to properly accelerate during
sprinting, cutting, or jumping.
ISOMETRIC
An isometric muscle action occurs when the contractile force is equal to the resistive force lead-
ing to no visible change in the muscle length (5,9). As the muscle shortens, elastic components
of the muscle lengthen. The muscle is shortening; however, there is no movement of the joint.
In athletic activities, isometric actions dynamically stabilize the body. This can be seen when
stabilizers isometrically contract to restrict a limb from moving in an unwanted direction. For ex-
ample, when cutting, the adductors and abductors will