HSE304 Lecture Notes - Lecture 2: Upper Motor Neuron, Lower Motor Neuron, Golgi Tendon Organ
Topic 2: Neural Adaptations to Strength Training
- Strength training: < 85%, 1-4 reps, induces greater neural benefits over
hypertrophy
- Increased agonist (prime mover) activation
- Appropriate synergist (brachialis, brachial radialus) activation
- Decreased antagonist (triceps) activation
- = Increase rate of force/force dev = Increased strength performance
Motor neuron excitability and motor unit during explosive movement
- Motor unit: motor neuron an muscle fibres it innovates – both U and L
- Upper motor neuron: those in the CNS (brain & spinal cord)
- Lower motor neuron: those that come out of the spinal cord and innovate
muscle
Modulation of muscle tension involves the concurrent variation in no. active
motor units and discharge rate - to increase force/time under tension
- 1: Motor unit recruitment increases
- 2: Within one motor unit increase in motor unit firing rate
- Larger muscles: with more motor units should be stronger
For force to be produced:
- Have to have orderly recruitment of muscles, slow twitch then fast
- Rate coding: one AP or 2 APS back to back, or steady firing of AP
- Synchronization: one motor unit fires at same time as other motor unit
- Can have one common output and 2 very different motor units working together
Stretch reflex
- Adaptations from strength
- Muscle spindle: located within muscle belly, detect stretch, sends information
to the brain, if muscle is in high tension – spindle fires, sends impulse to muscle
to contract
- Protective mechanism, can use this stretch reflex when jumping – using stretch
reflex by short sharp dip before jumping
- Golgi tendon organ: causes muscle to relax, work hand in hand to make sure muscle is
protected
- Interacts with antagonist muscle to relax while agnostic is being flexed
Motor unit adaptations to strength training
- Motor neuron and muscle fibres
After strength training:
- Recruit more muscle fibres, < amount force
- Brain should be able to fire more APs down to the motor unit /sec < force
- Increased rate of force development = < rate of force produced
- Motor unit excitability
- Strength training has higher motor unit synchronization than skill training
- Increase in excitability of muscle itself, can further increase excitability by
complex skill tasks
Document Summary
Strength training: < 85%, 1-4 reps, induces greater neural benefits over hypertrophy. = increase rate of force/force dev = increased strength performance. Motor neuron excitability and motor unit during explosive movement. Motor unit: motor neuron an muscle fibres it innovates both u and l. Upper motor neuron: those in the cns (brain & spinal cord) Lower motor neuron: those that come out of the spinal cord and innovate muscle. Modulation of muscle tension involves the concurrent variation in no. active motor units and discharge rate - to increase force/time under tension. 2: within one motor unit increase in motor unit firing rate. Larger muscles: with more motor units should be stronger. Have to have orderly recruitment of muscles, slow twitch then fast. Rate coding: one ap or 2 aps back to back, or steady firing of ap. Synchronization: one motor unit fires at same time as other motor unit.
