Download Proprioceptive Neuromuscular Facilitation (PNF) Stretching

HEALTH SCIENCES 365
Chapter 2 – Neuromuscular Fundamentals
Muscular System
Over 600 muscles (215 pair) comprising approximately 40% to 50% of body weight
Functions
 Movement
 Protection
 Support & Posture
 Heat Production
Muscle Nomenclature – usually named because one or more distinctive characteristics.
Often there is crossover among the various nomenclature characteristics.
Individual Muscle
Muscle Group
 Shape _______________________________
______________________
 Size _________________________________
 Number of divisions ____________________
______________________
 Direction of fibers ______________________
 Location ______________________________
______________________
 Points of attachment ____________________
 Action _______________________________
______________________
 Action & shape ________________________
 Action & size _________________________
 Location & attachment __________________
 Location & number of divisions ___________
Muscle Shape and Fiber Arrangements
Muscle shape and fiber arrangement play a role in the muscle’s ability to exert force and
the ROM through which it can effectively exert force.
1. Shape
 Cross-sectional diameter
 Ability to shorten
2. Fiber Arrangement (Two major types)
Parallel Arrangement (Fibers arranged parallel to length of muscle = § _______)
 Flat – thin & broad (Rectus Abdominus)
 Fusiform – spindle shaped with central belly that tapers (Brachialis)
 Strap – fibers arranged in a long parallel manner (Sartorious)
 Radiate – combined arrangement of flat & fusiform (Pectoralis Major)
 Sphincter – circular (Obicularis Oris)
Pennate Arrangement (Shorter fibers arranged obliquely to their tendons = § ______)
 Unipennate – run obliquely from a tendon on one side only (Biceps Femoris)
 Bipennate – run obliquely on both sides from a central tendon (Rectus Femoris)
 Multipennate – several tendons with fibers running diagonally between them
(Deltoid)
Muscle Tissue Properties
 Irritability – ability to respond to a _______________
 Contractility – ability to contract and develop ________________
 Extensibility – ability to be _______________________________
 Elasticity – ability to return to original ______________________________
 Tonus/Tonicity – a state of firmness of a muscle due to _________________
Muscle Terminology
 Intrinsic – muscle within or belonging solely to body part on which they act
 Extrinsic – muscles that originate outside a body part on which they act
 Action – specific movement of a joint resulting from a concentric contraction
 Innervation – nerve responsible to provide stimulus to muscle fibers
 Amplitude – range of fiber length between maximal and minimal lengthening
 Gaster (belly) – portion of muscle that increases in diameter as muscle contracts
 Origin – proximal attachment, usually least moveable part (exceptions?)
 Insertion – distal attachment, usually most moveable part (exceptions?)
Types of Muscle Contraction (to cause, control, or prevent joint movement)
Isometric (__________): A type of muscle contraction in which:
 Tension develops, no change in length of muscle or angle of joint - “preventing”
 Muscular Force __ Resistive Force
 ___________________ effect
Isotonic (__________): A type of muscle contraction in which tension develops,
“causing” or “controlling” joint movement (Two Types)
Concentric (positive contraction)
 Muscle shortens
 Muscular force __ Resistive force
 Body part moves against (_____)
gravity or external force
 _________________ effect
 Muscle(s) involved and
movement are the ____________
Eccentric (negative contraction or “action”)
 Muscle lengthens
 Muscular force __ Resistive Force
 Body part moves with (_________)
gravity or external force
 ___________________ effect
 Muscle(s) involved and movement
are ____________
Muscle Force – Velocity Relationship
-Concentric contraction against a light resistance = __________ velocity
-Increasing resistance = ___________ in the maximal velocity the muscle can contract
-Continuation of increasing resistance eventually = ___________ contraction if equal to
muscular force
-If resistance increases beyond muscular force = ___________ contraction
Role of Muscles
Agonist (___________): muscle that when contracting concentrically causes joint motion
Q. How do you determine which muscle groups (agonists) are involved?
Step #1: Identify what movement(s) the resistance is tending to cause
Step #2: The opposite muscle group is involved
 What does “involved” mean?
If contracting: ___________________________
If relaxing: _____________________________
Q. Why do muscles perform their particular actions?
1. Line of Muscle Pull – relationship of a muscle/tendon as it crosses a joint
a. __________________________________________________
b. __________________________________________________
c. __________________________________________________
2. Joints Functional Design – diarthrodial classification (planes of motion of a joint)
Antagonist: opposite side of the joint from the agonist
Stabilizer (__________): a muscle(s) that contracts to fix or stabilize a bone so that a
muscle can do its _____________________.
Agonist
Stabilizer
Stabilized Part
 Straight leg raise lying supine
_________
_________
____________
 Crunch/Curl up
Abdominals _________
Pelvis
 Neck Flexion
_________
_________
____________
 Handing off a gallon of milk
_________
_________
____________
“Static” Stabilization vs “Dynamic” Stabilization
Q. Why take a deep breath before performing a bench press?
Neutralizer: Muscle that contracts to counteract or neutralize the action of another
muscle to prevent undesirable motions. The result of the combination of:
1) ____________________________, and 2) ______________________________.

Movement/ Action: Inversion of foot
Muscles:
____________________
____________________
Common Action:
Subtalar Inversion
Neutralizing Actions: ____________________
____________________


Movement/Action: Lateral Arm Raises
Muscles:
____________________
____________________
Common Action:
_____________________
Neutralizing Actions: ____________________
____________________
Movement/Action: ___________________________
Muscles:
____________________
____________________
Common Action:
____________________
Neutralizing Actions: ____________________
____________________
Synergist: a muscle(s) that works with an ____________, yet is a partial
______________, and contracts to prevent __________________________________.
Agonist(s)
Synergist(s) Undesired Movement
 Making a fist
________
________
_________________
 Biceps curl (dumbbell)
________
________
_________________
 Hip flexion against resistance ________
________
_________________
Important: A muscle tends to perform all its actions when it contracts unless something
prevents those movements from occurring.
-If the stabilizer muscle is a non-antagonistic muscle  it is called a “_____________”
-If the stabilizer muscle is an antagonistic muscle  it is called a “_____________”
-If the stabilizer muscle is an antagonistic muscle + a common action  it is called a
“_____________”
Neuromuscular Interaction
Peripheral Nervous System (PNS) – Spinal Nerves
 Spinal Cord – pathway between Central Nervous System and PNS
 Motor (efferent) nerves & Sensory (afferent) nerves
 Myotome – a muscle or group of muscles supplied by a specific spinal nerve
 Dermatome – a defined striplike or band area of skin supplied by a single spinal
nerve root (dorsal)
 Cutaneous Distribution – an area or patch of skin supplied by a specific nerve
 Reflexes
a. Biceps Brachii (C5)
c. Patella – knee extensors (L3 & L4)
b. Triceps Brachii (C7)
d. Achilles (S1)
Proprioception and Kinesthesis
Proprioception – the process/mechanism by which the body is able to regulate posture
and movement by responding to stimuli originating in the proprioceptors (sensory
receptors located in the skin, joints, muscles, and tendons). They provide feedback
relative to tension, length, contraction state of muscle, position of body and limbs, and
movements of joints. These sense organs are vital to kinesthesis – the conscious
awareness of the position and movement of the body in space and aid in the performance
of complex coordinated movements.
STRETCHING TECHNIQUES, PROPRIOCEPTORS, & REFLEX ACTIVATION
There are basically three stretching techniques (Ballistic, Static, & Proprioceptor Neuromuscular
Facilitation). All three types of stretching are effective in developing flexibility. One however, ballistic
stretching, can be harmful by causing tears in muscle membranes and therefore is not the recommended
technique for development of flexibility.
1. Ballistic Stretching Technique: stretching where there is a rapid bouncing movement in and
out of the stretch position, where the end position is not held.
2. Static Stretching Technique: stretching is slow and constant where the end position is held.
3. Proprioceptor Neuromuscular Facilitation (PNF) Stretching Technique: stretching
performed usually with a partner and involves both passive movement and active (concentric
and isometric) muscle actions.
All stretching techniques require movement of a body segment to a point of resistance in the
ROM. This stretching movement can be done either actively or passively.
 Active stretch: when the person stretching supplies the force of the stretch.
 Passive stretch: when a partner or stretching machine provides the force for the stretch.
Muscle Spindles & the Myotatic Reflex (also called the Stretch Reflex)
During a ballistic stretching movement, the muscle spindle is activated and a sensory neuron sends an
impulse to the spinal cord, where it synapses with a motor neuron which carries a message back to he
muscle being stretched causing it to contract, called a myotatic reflex (or stretch reflex). Muscle spindles,
being sensitive to the length and rate of change in muscle length, indicate the degree to which the muscle
must be activated to contract to overcome a given resistance. As a load increases, the muscle is stretched to
a greater extent, and engagement of muscle spindles results in greater activation of the muscle. This muscle
activation process is thought to aid in athletic performance, maintaining of functional position, and in
maintaining upright positioning. However, its use in stretching for the development of flexibility is
questioned because of the increased risk of muscle injury, especially if a previous injury exists.
Golgi Tendon Organs & the Inverse Myotatic Reflex
During a static stretch movement (slow, sustained motion that lasts at least 10 seconds), tension increases
within the muscle and a sensory neuron from the Golgi tendon organ (GTO) is activated and sends an
impulse to the spinal cord, where it synapses with an inhibitory interneuron in the spinal cord, which in turn
synapses with and inhibits a motor neuron serving the same muscle. As tension in the muscle increases,
discharge of the GTO increases. The result is a reduction in tension within the muscle, causing it to
reflexively relax, called an inverse myotatic reflex (sometimes called autogenic inhibition).
Note: Because of the slow rate of change of the muscle length the muscle spindles are not activated. Thus,
whereas muscle spindles facilitate activation of the muscle, neural input from GTOs inhibits muscle
activation. This inhibitory process is thought to provide a protective mechanism from development of
excessive tension and potential muscle tearing.
Myotatic Reflex (Stretch Reflex)
Inverse Myotatic Reflex (autogenic inhibition)
Proprioceptive Neuromuscular Facilitation (PNF) Stretching
PNF stretching was originally developed as part of a neuromuscular rehabilitation program designed to
relax muscles with increased tone. It has since expanded to the training of athletes as a method of
increasing muscular flexibility. PNF techniques are usually performed with a partner and involve both
passive movement and active (concentric and static) muscle contractions. PNF stretching may be superior
to other stretching methods because they facilitate muscular inhibition.
During PNF stretching, three specific muscle actions are used to facilitate the passive stretch. A static
(isometric) muscle contraction of the antagonist (the muscle being stretched), which produces tension
within the muscle, is used before the passive stretch to cause a reflexive relaxation of the muscle during the
subsequent passive stretch, called the inverse myotatic reflex (or autogenic inhibition). A static stretch of
the antagonist muscle increases tension within the muscle activating the GTO resulting in the associated
activation of the inhibitory interneuron and corresponding reduction in tension within the muscle, causing it
to reflexively relax, called an inverse myotatic reflex (sometimes called autogenic inhibition). A
concentric muscle contraction of the agonist (opposing muscle to the antagonist or muscle being stretched)
performed simultaneously while the muscle is being passively stretched results in reciprocal inhibition
(relaxation of the muscle being stretched via activation of the GTO and the associated inhibitory
interneuron).
 The static (isometric) muscle contraction is referred to as contract.
 The concentric muscle contraction of the agonist is referred to as agonist contract.
 The passive, static muscle stretch is referred to as relax.
Contract-Relax (CR) technique
Contract-Relax-with Agonist Contract (CRAC) technique
Neuromuscular Concepts
Motor Unit – a single motor neuron and all the muscle fibers it innervates
All or None Principle – all muscle fibers in a motor unit contract maximally or not at all
Muscle Tension Development – the difference between a muscle contracting to lift a
small resistance verses a muscle contracting to lift a heavy resistance is the number of
muscle fibers recruited. The number of fibers recruited may be increased by:
1. ________________________________________________________________
2. ________________________________________________________________
3. ________________________________________________________________
Muscle Length – Tension Relationship
The greatest muscle tension can be developed when the muscle is stretched between
_____% and _____% of its resting length. Why?

Seated leg extension

Prone hamstring curl

Vertical jump
The least muscle tension results when a muscle is shortened to approximately _____% to
_____% of resting length.
Active & Passive Insufficiency
Active Insufficiency: When a muscle becomes shortened to the point at which it cannot
generate or maintain active tension.
Passive Insufficiency: When the opposing muscle becomes stretched to the point at which
it can no longer lengthen and allow movement.
Angle of Pull
The angle formed between the 1)__________________________________ and the
2) _____________________________________
a. Reference angle is the angle toward the joint
b. Rotary component - that muscular force that acts perpendicular to the long axis
of the bone/lever
 When angle of pull is 90° = ______% rotary force
Note: At all other degrees of angle of pull, one or two of the other components of
force (non-rotary) is operating “in addition to” the rotary component.
Non-Rotary Components
If angle of pull is <90° = _____________
Why?
_____________________________
If angle of pull is >90° = _____________
Why?
_____________________________
Angle of Resistance
The angle formed between the:
1)_________________________________ and the
2) _______________________________________________________.
 Differentiate between applied and attached

The angle of resistance is zero if the *center of gravity at the segment lies
on a line between the ____________ and the _______________________
*Center of Gravity: a point representing the weight center of an object. A point
in a body (segment) about which all the parts exactly balance each other.
Rotary Component
a. At a 90° angle of resistance 100% of the energy of resistance is causing the lever to __
_______________________________________________________________________
b. At a 0° angle of resistance 100% of the energy of resistance is causing either a:
 _________________ element
 _________________ element
 There is no force causing movement of the bone/lever around its axis
Biarticular Muscles
1. Can cause, control, or prevent movement at more than one joint
2. Increased flexibility
3. Decrease the number of muscles required for same movements ( muscle mass)
4. Can maintain a relatively constant length and tension at both joints as go through a
range of motion
Biarticular Muscles & Movement Patterns
1. CONCURRENT MOVEMENT PATTERN
Muscle movement pattern that allows the muscles to maintain a relatively constant length
and tension at both joints as go through a range of motion.
Squat:
1. When concentrically contract Rectus Femoris = knee extension  puts hamstrings on
stretch. Why? ____________________________________________________________
Benefit? __________________________________________________________
2. When concentrically contract Biceps Femoris = hip extension  puts quadriceps on
stretch. Why? ____________________________________________________________
Benefit? __________________________________________________________
Lombard’s Paradox: Question: How is it possible for two muscles that are
antagonistic to each other contract and both contribute to the desired action or
movement?
 Involves comparison between two antagonistic muscles
 Both muscles must be biarticular
Parallel Squat
 Rectus Femoris

Biceps Femoris
Muscle
Knee
Rectus Femoris 4.4
Biceps Femoris 3.4
Hip
3.9
6.7
MFA
Longer at knee
Longer at hip
2. COUNTERCURRENT MOVEMENT PATTERN
Muscle movement pattern that results from the concentric contraction of a biarticular
muscle that produces its intended movements. Results in increased tension and stretch of
the antagonistic muscle.
Guidelines for Muscle Testing and Exercise
1. Test both sides - comparison
2. _______________ the muscle
3. Stabilize the _______________ segment
4. Apply a _____° angle of resistance (or as close as possible)
5. Apply the resistance to the _______________ end of distal segment
6. To overcome a deformity
 Stretch tight muscle groups
 Strengthen the weak muscle groups
 Maintain _______________ _______________
 An external force is usually required
Stages of Development of Acquired Musculoskeletal Deformities
1. First Degree (curable by exercise – strengthening the weak, stretching the tight)
a. Soft tissue: _______________________________________________
b. Bone tissue: ______________________________________________
c. Corrective treatment: _______________________________________
2. Second Degree (improvable by exercise)
a. Soft tissue: _______________________________________________
b. Bone tissue: ______________________________________________
c. Corrective treatment: _______________________________________
________________________________________________________
3. Third Degree (little if any change achieved with exercise)
a. Bone tissue: ______________________________________________
Assessing Posture: the relationship of body segments to one another
 Four (4) Key Words: Straight, Vertical/Horizontal, Symmetrical, Non-rotated
Lateral Line of Gravity
Anterior Line of Gravity
a. *Mastoid process
a. Anterior superior iliac spine (ASIS)
b. Posterior to cervical spine
b. Bisects knee
c. Bisects cervical-thoracic spine
c. Bisects ankle
d. Anterior to thoracic spine
d. Bisects foot at second toe
e. Bisects thoracic-lumbar spine
f. Posterior to lumbar spine
g. *Bisects shoulder joint
h. *Bisects greater trochanter
i. *Bisects knee (posterior to patella)
j. *Ant. to lateral malleolus (1-1.5”)