Neuromuscular System

The Neuromuscular System

n Consists of:

• Nervous System

n Central Nervous System – Brain and Spinal Cord

n Peripheral Nervous System

• Somatic system – excites muscle activation

• Autonomic system – excites or inhibits muscle activation

n Sympathetic – excites

n Parasympathetic – inhibit or slow down

• Muscular System

n Skeletal

n Cardiac

n Smooth

The Neuromuscular Connection

n Motor Unit

• Defined as the nerve + the muscle fibers that it innervates

n The ratio of muscle fibers to nerve relates to function

• Delicate, precise work requires a lower muscle fiber number to nerve ratio, e.g. 10 muscle fibers to one nerve (eye muscles)

• Less complex movements require a higher muscle fiber number to nerve ratio, e.g. 3000 muscle fibers to one nerve (leg muscles

The Fiber Types

n Fiber Types:

• Type I = slow-contracting

• Type II = fast-contracting

n Type IIa – has both anaerobic and aerobic abilities

n Type IIb – has primarily anaerobic ability

n Type IIc – combination of IIa and IIb

Comparison of Fiber Types

Comparison of Fiber Types

Fiber Type Composition in Elite and Non-athletes

Proprioception

n Process of communication between muscle and central nervous system

n Components

• Muscle Spindles

• Golgi Tendon Organs

The Muscle Spindle

n Proprioceptor that runs along the length of the muscle fiber

• Provide information concerning muscle length and rate of change

n Action:

• When muscle is lengthened, spindle is stretched

• Sensory fibers in spindle send impulse (afferent) to spinal cord/brain

• Spinal cord/brain send signal (efferent) back to muscle

• Muscle contracts

The Muscle Spindle

The Muscle Spindle

The Golgi Tendon Organ

n Proprioceptor located in the tendon

• Activated when tendon is stretched

n Action:

• When muscle is shortened greatly, tendon is stretched

• Sensory fibers in tendon send impulse (afferent) to spinal cord/brain

• Spinal cord/brain send signal (efferent) back to muscle

• Muscle relaxes

The Golgi Tendon Organ

Joint Receptors

n Proprioceptors located in the joints which response to movement

• Assist the joint region, through muscle activation surrounding joint, in responding to appropriate positioning during physical activity

Proprioceptive Neuromuscular Facilitation (PNF)

n An approach to therapeutic exercise that utilizes:

• Inputs

n Proprioceptive

n Cutaneous

n Auditory

Proprioceptive Neuromuscular Facilitation (PNF)

n Involves 3 basic component movements:

• Flexion-extension

• Abduction-adduction

• Internal-external rotation

Proprioceptive Neuromuscular Facilitation (PNF)

n Means by which we can manually override the inhibitory signals to enhance the stretch of a muscle Types:

• Contract-relax

• Hold-relax

• Slow-reversal hold

PNF

n Contract-relax Technique

• Move body part until resistance felt

• Subject then contracts muscle being stretched against a moving (active) resistance

• Resistance applied progressively for 10 sec or fatique

• Subject relaxes for 5-10 seconds

• Repeat procedure 3-5 times

PNF

n Hold-relax Technique

• Move body part until resistance felt

• Subject then holds body part in place while therapist progressively applies isometric resistance

• Resistance applied progressively for 10 sec or fatique

• Subject relaxes for 5-10 seconds

• Repeat procedure 3-5 times

PNF

n Slow-reversal Hold Technique

• Move body part until resistance felt

• Subject then holds body part in place while therapist progressively applies isometric resistance

• Resistance applied progressively for 10 sec or fatique

• Subject relaxes antagonist as agonist is contracted for 10 seconds

• Repeat procedure 3-5 times

PNF

n Means by which muscle strength, endurance and coordination can be improved

n Types:

• Rhythmic coordination

n Regain strength through ROM slowly

n Passive, assistive, active ROM

• Repeated Contraction

n Enhance strength at weak point in ROM

n Resistance through ROM until fatique, quick stretch, then continue resistance

• Slow-reversal

n Promotes reciprocal coordination between agonist and antagonist

n Resistance through ROM, then reverse ROM against resistance

PNF

n Types (continued)

• Slow-reversal hold

n Develop strength a specific point in ROM

n Isotonic contraction, hold, repeat in specific ROM

• Rhythmic stabilization

n Develop max strength at specific point in ROM

n Isometric contraction of agonist, followed by isometric contraction of antagonist, etc.

Neuromuscular Adapations to Exercise

n Adaptations to Resistance Training

• Increase in muscle Size (hypertropy)

• No change in fiber # (hyperplasia)- has not be proven in humans

• Increase in strength

• Increase in movement speed

• No change in aerobic capacity

• Increase in anaerobic capacity

Neuromuscular Adapations to Exercise

n Adaptations to Aerobic Training

• No change in muscle Size

• No change in fiber #

• No significant change in strength

• No change in movement speed

• Increase in aerobic capacity

• No change in anaerobic capacity