Neurological Considerations

Nervous system: controls movement through sensory input and motor output

Coordinating sensory and motor together gives us motor control

CNS:

  • Brain and Pinal Cord: movement is controlled and monitiored

PNS:

Neuron: functional unit of nervous system

Sensory Neurons: enters spinal cords, muscle back to system, AFFERENT pathway, gives us information

  • stretch, heat/pressure, tension, pain

  • Reflex: involuntary response to stimuli

  • Monosynaptic reflex arc: stimulation of sensory neuron facilitates the simulation of a spinal motor neurons

  • Myotatic reflex: “stretch reflex” through monosynaptic reflex artc, initiated, by stretching muscle, marries AFFARENT and EFFERENT pathway, its why we go down before we jump, stretch in contraction out

Motorneurons: exist spinal cord, information from system to muscle, EFFERENT pathway

Innervation ratio: number of fibers controlled by one neuron

  • Eye muscles 1:10 - more presicion less strength

  • Gastrocnemius 1:1600 - more strength less precision

Muscle Spindles: parallel to muscle fibers, respond to stretch, connect to fascicles

  • Type 1 of afferent neurons: measures velocity

  • Type 2 of afferent neurons: measures length

If the stretch threshold is reached

  • contraction of stretched muscle (stretch reflex)

  • synergist muscle activity (autogenic facilitation)

  • reciprocal inhibition; if we want to extend knee hard the hamstrings can’t be turned on to flex knee, agonist contracts the antagonist needs to relax

Stretch shortening cycle: concentric muscle action preceded by eccentric muscle action

  • Results in enhanced concentric force generation:

  1. elastic energy storage

  2. increased time to develop tension

Golgi Tendon Organ (inverse stretch reflex)

  • found at musculoskeletal junction - neurotendinous spindle

  • causes relaxation of muscle as protection
    - think of the jumping example the guy who was able to jump and move right to the next

  • when we desensitized it leads to a greater contraction of the muscle

Ruffini ending- found in joint capsule, responds to position and changes and velocity

Pacinian Corpuscle- found in joint capsule and connective tissue, response to pressure created by muscle and pain in the joint

  • when we tape, wrap, or brace an injury it gives us neurological education on our joints position, pressure etc. It isn’t there to entirely stabalize rather it is there to help us rebuild that neurological connection

Neural adaptation

  • better coordination of motor unit activation

  • increased input to agonist and synergist

  • greater inhibition of antagonist

  • “learning effect” levels off after 4-5 weeks… is that enough time to get hypertrophy? NO, in children we don’t see that hypertrophy espectially. this is coming from us learning, better coordination etc

specificity of training

  • important enhancement of neural input to muscle

  • Bilateral deficit: decrease in neural stimulation as a task gets more complex (think not being able to curl with two hands but you can curl same weight with one hand)

  • cross-over effect: neurologically enhances the activity increases voluntary strength in contralateral limbs (think of one arm is in sling, should you still press in the other arm? yes! Because you are keeping up with the neurological pathways)

plyometrics: it is high velocity, high force resistance training, desensitize gto, uses nervous system training

post activation potentiation: heavy loading prior to explosive activity induces a high degree of CNS stimulation which results in greater motor unit recruitment (think heavy back squat followed by vertical jump)

flexibility is the terminal range of motion of a segment, you are not actually lengthening muscle fibers, that takes a ton of strength to sheer those forces, we do feel loser after stretching but that is a neurological thing, we perceive its okay to go to some ranges and after we feel comfy to stretch further

  • stretching is just a modality

  • we have to increase mechanical tension at the end range and that is what actually changes mobility, if you stretch then load, then you actually are promoting long term changes

active range of motion produced by agonist

passive range of motion agonists are relaxed

does increased flexibility protect against injury? inconclusive

influence on force production and power output? may have a negative effect, you are desnsitiving stretch reflex when static stretching then lifting, if you do it then wait maybe youll be okay but jumping form stretching to lifting you will desensitize your stretch reflext

static stretch: decreases type 1 a stretching response

ballistic stretching: stimulation of type 1a sensory neurons