Neuromuscular Adaptations to Conditioning - PowerPoint PPT Presentation

Loading...

PPT – Neuromuscular Adaptations to Conditioning PowerPoint presentation | free to download - id: f64b1-ZDc1Z



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Neuromuscular Adaptations to Conditioning

Description:

Discuss two ways to increase force production. Discuss ... Guillain-Barre syndrome. Parkinsons. ALS. Neural Components of Muscle Activation. Motor unit ... – PowerPoint PPT presentation

Number of Views:107
Avg rating:3.0/5.0
Slides: 35
Provided by: facultyF4
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Neuromuscular Adaptations to Conditioning


1
Neuromuscular Adaptations to Conditioning
  • Chapter 2

2
Objectives
  • Discuss the concept of a motor unit
  • Discuss different fiber types
  • Discuss two ways to increase force production
  • Discuss adaptations to the neural system

3
The Nervous System
  • Central (CNS)
  • Brain
  • Spinal cord
  • Peripheral
  • Nerves
  • Axons

4
(No Transcript)
5
Neuron and Motor Unit
  • Neuron is a single nerve cell
  • 1014 neurons in brain
  • Synapses convey information via chemicals
  • Afferent-from periphery to CNS
  • Efferent-from CNS to periphery
  • Neuron body, dendrites and axon (myelin sheath)

6
Action Potential
  • Alteration in permeability
  • Sodium influx and potassium outflow
  • Negative to positive
  • Nerve conduction velocity
  • 120 m/s or 270mph for myelinated
  • 400 f/s
  • 5 m/s or 2mph for unmyelinated
  • 16 f/s

7
(No Transcript)
8
(No Transcript)
9
(No Transcript)
10
Phospholipid Bilayer
11
Slow or Block Nerve Conduction
  • Demyelination
  • Multiple sclerosis
  • Guillain-Barre syndrome
  • Parkinsons
  • ALS

12
Neural Components of Muscle Activation
  • Motor unit
  • Acetylcholine (ACH)- primary neurotransmitter at
    the neuromuscular junction
  • Frequency of nerve impulses
  • Twitch
  • Summation
  • Tetanus

13
Electrical Stimulation
  • Motor nerve innervation
  • Latent period (.01)
  • Contraction phase (.04)
  • Relaxation phase (.05)
  • Fast vs. slow time varies

14
(No Transcript)
15
(No Transcript)
16
Threshold
  • AP results from the quick and dramatic alteration
    to ionic permeability following chemical or
    electrical intervention. Muscle resting at -90
    millivolts
  • After stimulation of an excitable cell membrane
    sodium ions move into the cell and the
    transmembrane potential is reduced - referred to
    as depolarization
  • When a critical voltage level called the
    threshold is reached, voltage-sensitive sodium
    gates are opened followed by slower acting
    potassium gates (move out)
  • At 35 millivolts the sodium channels and the
    potassium channels are fully opened, resulting in
    restoration of the negative transmembrane
    potential - called repolarization
  • The amplitude of voltage changes in response to
    stimulation is constant from stimulus to stimulus
    and is described as "all or none"
  • Electrical stimulation of excitable cells is
    possible up to 1000 pps.

17
(No Transcript)
18
(No Transcript)
19
Temperature
  • Heat increases speed and force output.
  • Cooling increases relaxation time.
  • Heat may increase speed by 20.

20
Size Principle of Muscle Recruitment
F I B E R S U S E D
TYPE IIb
TYPE IIa
TYPE I
MUSCULAR FORCE
21
Reflexes
  • Sensory receptors send a signal to a motor neuron
  • Motor neuron sends signal to the effector
  • Stretch shortening cycle (SSC)?

22
(No Transcript)
23
Stretch Shortening Cycle
  • Concentric force is increased as a function of
    eccentric action or stretching.
  • Increased force with speed of the motion.
  • Stored elastic energy responsible.

24
Fatigue
  • Repeated contractions diminish relaxation time.
  • Neural signals continue to propagate.
  • Contracture occurs at the muscle site.

25
Mechanical Factors
  • Angle of pull is optimum at right angles or 90
    degrees to the bone.
  • Length is optimum at midpoint or resting length.

26
Exercise Modes
  • Isokineticconstant velocity.
  • Isotonicconstant resistance (DCER).
  • Isometricstatic and without muscle movement.

27
Neuromuscular Adaptations to Exercise
  • Hypertrophy- enlargement and increase in number
    of muscle myofibrils (not fibers), increasing the
    size of actin and myosin
  • Hyperplasia-increase in the number of fibers (not
    in humans, only in birds).
  • Fast twitch muscle fibers hypertrophy to a
    greater extent than slow twitch muscle fibers
  • Early increases in muscle strength have a large
    neural component
  • Long term increases in strength also have a
    neural component

28
Moritani and deVries Hypertrophy vs. Learning
29
Atrophy vs. Hypertrophy
30
Electromyography (EMG)
  • Records electrical signals from the brain.
  • EMG reflects muscle activation.
  • Surface electrodes (summated) or fine needle
    electrodes (individual).
  • Amplitude increases with recruitment (summation).
  • Integration of signal equals true mean of firing
    (RMS).

31
EMG cont
  • Positive relationship between EMG and
    force/velocity.
  • A measure of intensity.
  • Efficiency of electrical activity stronger
    individuals require less activation.
  • Learning curve demonstrates greater force with
    less EMG.

32
EMG and Fatigue
  • EMG increases with fatigue.
  • Recruitment responsible.
  • Local fatigue is a function of individual muscle
    and joint.

33
Resistance Training and Aerobic Power
  • Resistance training does not improve aerobic
    power
  • Resistance training does not impair an
    individuals ability to develop maximal aerobic
    power
  • Aerobic training does not enhance muscle strength
    or size
  • Aerobic training may compromise the benefits of
    strength training on muscle force production

34
Next Class
  • Chapter 6 Endocrine
About PowerShow.com