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PNF Stretching

PNF Stretching PDF (not all-inclusive)

QuestionAnswer
What are proprioceptors? Specialized sensory receptors located within joints, muscles, & tendons
What do proprioceptors do? Relay info concerning muscle dynamics to conscious & sub-conscious parts of our CNS
Processing of proprioceptive information Most is processed at the sub-conscious levels so we don't have to think about tasks such as maintaining posture or position of our body parts
What 5 components are involved in reflex arcs? Receptor Sensory neuron Integration center Motor neuron Effector
What is the receptor? Site of stimulus action
What is a sensory neuron? Transmits afferent impulses to the CNS
Simple reflex arc? Single synapse between a sensory (afferent) neuron & a motor (efferent) neuron- monosynaptic
Complex reflex arc? Multiple synapses with chains of interneurons- polysynaptic reflexes (withdrawal or crossed-extension)
Parts of a Muscle Spindle 3-10 infrafusal fibers, which provide input to regulate the activity of muscle. Extrafusal fibers are effective & when stimulated, they contract, shortening the muscle
What influences the muscle spindle? Rate & degree of stretching
What does stretching do to the muscle spindle? Increases tension & increases rate of action potential generation.
Muscle Contraction Reduces tension on the spindle & lowers the rate of action potential generation
What happens when impulses from mm spindles are transmitted at a high frequency? Extrafulsal fibers are excited, causing the muscle to contract This contraction attempts to prevent the muscle from stretching any further
Afferent Impulses Travel to the spinal cord, synapse with motor neurons & interneurons. Motor neurons send activating impulses to agonist, causing contraction preventing any further stretch.
Interneuron Synapse Inhibits action of the antagonist, which effectively prevents antagonist from resisting contraction. This is called reciprocal inhibition.
Where are GTOs located? Tendons near the musculotendinous junction
How is a GTO activated? Muscle stretch. As muscle tension increases, impulses from the GTO increase. Neural input from GTOs inhibits muscle activation
GTOs send afferent signals to CNS interneurons to perform 2 functions. What are they? Inhibit motor neurons serving the contractile muscle (autogenic inhibition); Stimulate motor neurons serving the antagonistic muscle group
Overal, what happens because of the GTO reflex? Contracting muscle relaxes & lengthens as the antagonist contracts & shortens
What is reciprocal inhibition? Relaxation that occurs in the muscle opposing the muscle experiencing increased tension
What is autogenic inhibition? Relaxation that occurs in the same muscle experiencing increased tension
What is disinhibition? Ability of motor cortex to override autogenic inhibition
How does PNF compare to other types of stretching? PNF is superoir for increasing ROM when compared to static/passive & ballistic stretching, esp. in respect so short-term gains. PNF is more engaging & less boring.
How many repetitions of PNF should be performed to achieve the greatest gains? at least 4
How long should contractions be held in a PNF stretch? 3-10 seconds
What is the optimal contraction intensity in PNF stretching? 65% of maximal voluntary isometric contraction
Hold-Relax Stretching Range-limiting mm is lengthened to point of limitation; Pt performs sub-max isometric contraction for 5-8" then relaxes; Limb is passively moved into new range as the muscle is elongated
Contract-Relax Stretching Same as hold-relax, except instead of an isometric contraction a strong, small range isotonic contraction of the restricting mm (5-8") is performed. Rotation should be allowed during contract-relax.
What is the aim of contract-relax? Take advantage of autogenic inhibition from GTOs
When should hold-relax be used instead of contract-relax? Acute injury or if active ROM is painful; If contraction of restricting mm is too painful/weak, can reverse the direction of contraction
Hold-Relax with Agonist Contraction Mm lengthened to point of limitation; Pt performs sub-max isometric contraction b/t 5-8"; Limb actively moved by pt into new range via concentric contraction of mm opposite range-limiting mm
What type(s) of inhibition is used by hold-relax with agonist contraction? Autogenic & Recriprocal; Agonist contraction may also be useful for initiating neuromuscular control in newly gained ROMs.
Created by: 1190550002