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Special Populations > BioMech > Flashcards

BioMech Flashcards

1
Q

What is EMG?

What does it record?

What does it measure?

A
  1. Electromyography
  2. Motor Unit Activity (super imposed)
    Decending drive
    Sum of all AP’s
  3. Electrical Activity
    Change of membrade potnential
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2
Q

Terms:
Descending Drive
Motor Neuron
Motor Unit

A
  1. Motor info from brain/spinal cord
  2. Neuron cells that carry sig. away from CNS
  3. Alpha MN and all muscle fibres it innervates
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3
Q

4 Main Parts of Neuron/What they Do?

A
  1. Dendrites- Communication
  2. Axon Terminals - Connects to other muscle/nerve
  3. Mylen Sheath - Protective Fat
  4. Nodes of Ranvier (Unmilinated. Speed Up)
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4
Q

Symbol for Sodium and Potassium
Where is each one chilling at RMP

A

Sodium = NA + (extra cell space)
Potassium = K (cyto)

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5
Q

Layers of a muscle

Little description of each

A
  1. Muscle (Surrounded by Epi)
  2. Muscle Fascicle (Surrounded by Peri)
  3. Muscle Fibre (Surrounded by Endo)
  4. Myofybril
  5. Myofilament

Epi - transfer to bone
Peri - cushion
Endo - nerve and blood
Fibril - Sarco in series (80% of muscle)

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6
Q

sEMG vs iEMG
What?
Pros and Cons

A

Surface - Non invasive. Multi Unit. Skin Impede
Indwelling - Invasive. Single unit. No skin (high bf%)

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7
Q

What are some factors affecting sEMG

A

Fibre Diameter
# of muscle fibres
electrode to skin interferane
signal conditioning (how we process sig)
# of active mu
tissue
mu firing rate
fibre type
location of fibre
muscle fibre conduction velo
distance from skin to mu

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8
Q

Sliding filament theory
What is it?
What are the layers

A
  1. Muscle surounded by epi
  2. Fasicle surouded by peri
  3. Fibre surounded by edo
  4. Fibirl containing sarcomenere
  5. Filaments - Myo (Thick dark A Band . H Zone) Actin (Light thin I band. Z line)
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9
Q

EMG prep

A
  1. Clean skin
  2. @ Belly.
  3. Parallel wtih fibre 1.5-2cm apart
  4. Not @ Tendon/edge/fat
  5. Away from power
  6. Consider movement
  7. Signal check : noise ratio
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10
Q

Processing Data

A
  1. DC Bias removal (subtract mean)
  2. Rectify (2+3 = linear envalope. positive)
  3. Filter
  4. Normalization (reference point…MVC)
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11
Q

Run down of AP

A
  1. K (Pot) in cytosol of cell
  2. NA (sod) outside of cell @ -70 MV
  3. Depolerize (-70-55mv) ^15 mv NA in!
  4. Repol = K back in
  5. Hyper pol..little over shoot
  6. AP makes it down the neruon
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12
Q

Two types of EMG arangements

Types of EMG

A

Bipolar (2 w ground to reduce noise)
Monopoalr (1 with more noise)

semg- non invasive. Skin. More MU’s
iemg- no skin. single cell. direct resource

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13
Q

3 Areas to use EKG

A

Sport
Infer force. Problems. Identify fatigue. Optimal exercise

Medicine
Diagnose. Rehab. Abnormal

Ergo
Posture. Risk. Ergo Design

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14
Q

Electircal potnential

A

Diff of charge carried across membrane

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15
Q

Saltatory conduction

A

Notes of ranvier and their importance

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16
Q

EMD

A

Electro magnetical delay
50-200ms
Training elims, then goes back up after a while

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17
Q

How to charcterize muscle

A

Twitch/Speed
Tenson/force
Fatiuge/ endurance
F2b has more cross bridges

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18
Q

Decending drive

A

Info from brain to spinal

19
Q

MU

A

@motor neuron and all the muscles it inervates

20
Q

RMP

A

Neuron @ no signal. AKA Steady state minus leakage .

21
Q

EMD

A

Electro Mechnaical Delay

22
Q

Saltatory Conduction

A

Skipping the mylen sheath

23
Q

Electrical potential

A

Differences of charge carried across membrane

24
Q

Heneman’s 2 Theory

A
  1. Rate coding
    -Twitch: Single, Wave sum, unfused and fused
    Smaller muscles
  2. Recruit more MU’s
    -small to big
    -fat resistant to fat
    -Fine tune
25
Q

Draw F/V or Movement Velo

A

Eccentric - Max length Velo
Iso
Con - Max Short Velo
Force on Y ^
Velo on X <>

26
Q

EMG Force relationship

A

-Large Mu’s closer to skin
-2.2 Optimal cross bridge
-\/ relaibility @ max contract
-works best with iso
-Recruitment < Rate coding

27
Q

Fatiuge

A
  1. Exercise enduced
  2. Recoverable
  3. Reduction of force.
    Can be measurable
28
Q

Twitch occlusion equation

A

ST/PT X 100 = % innactive

29
Q

2 Areas of Fatiuge

A
  1. Central<ITT> :
    Brain and spine
    Rate code down
    Sense/Afferent Down
    Cortical Down
    Motivation and Effort will help!</ITT>
  2. Perifpheral
    @Axon, NMJ, @MN, Muscle
    AP Mag down
    AP Failrure
    Ach Down
    H+ Up
    ADP Up
30
Q

Asses Fatiuge with EMG

A

Submax becomes max
@ MAx - emg goes down
@ submax - emg goes up - Recruit more Mu’s

31
Q

Quatify Fatiuge

A
  1. Measure: RXN , MVC, Speed, Power, Balance, endurance
  2. ITT
  3. EMG Mag and FRQ
  4. Blood Test / Biopsy
  5. TMS (Corticol excitability)
32
Q

Age

A

Transient = M fatiuge and can recover

Weakness means perminant

Mass down. Mus down. Task failure up.

Females better. Why? Mass, substrate utilizse , NMJ, muscle morphology

33
Q

Sex Differences

A
  1. Mass
  2. Morphology
  3. Substrate utilization
    4.NMJ Activation
34
Q

Muscle Characteristics

A
  1. Lengthen
  2. Shorten
  3. Excitable
  4. Elastic
35
Q

Two Categories of Fatigue
Where?
What happens?
Measure?
How to recover?

A

Peripheral
Where: Muscle, Neuron, MU
What happens: \/ AP magnitude, /\ adp, \/ force, /\ h, slow ach, poor k/na restore.
Measure: EMG
How to recover: Rest

Central:
Where: Brain, brain stem, spinal
What happens: \/ Rate code, \/ signal
Measure: ITT
How to recover: Motivation

Central

36
Q

Muscle Shapes and Organizations

A

Pinnate (Diagonal to tendon)
-Shorter Fibres, than muscle (remember muscle length doesnt equal fibre length)
More Force. Less distance = less velo

Parallel (to long axis of muscle, more short, more velo)
1. Fusiform/Spiral
2. Circle
3. Convergent / Radiant
4. Flat
5. Strap

Less force. More distance = more velo

37
Q

Two types of CSA and a few points on each

Whats the PSCA Equation

A

Anatomical
-Relative to side

Physiological
-Better predictor of force
-Perpendicular to muscle long axis
-Not orientated in line of action

Long PSCA & Short fibres = more force
Short PSCA & Long fibres = more velo

(Volume x Cos B(Pen angle)) / Fibre Length

38
Q

Actin and Myosin Bands/Lines/Zones

A

Dark Thick Protein Myosin - A Band + H Zone
Thin Light Polypeptide Actin - I Band + Z Line

39
Q

Volume or Area is a greater contributor to muscle force?

Discuss

A

Area

Long muscles have more velo,
Shorter have more force.

Short and thick = force /\

40
Q

What is pennation angle

A

Angle of muscle fibre and line of pull

41
Q

Hill muscle model components

Draw the force length relationship.

A

SEC - Series component - Tendon
PEC - Parallel elastic component -Epi, peri, endo
CC - Contractile component - muscle

42
Q

3 Muscle FXN

A
  1. Stabilize
  2. Produce movement
  3. Posture

Others?
Heat, support, control

43
Q

4 Examples of Muscle Plasticity

A
  1. Electric stim : Mice all day stim. FG –> to SO Characteristics
  2. Casting :
    length can increase with casting or long exposure.
    Return when removed.
    Muscles generate force to where they were stuck
  3. Train vs untrained : increase length of sarco when movements are of incresed length. Up hill vs downhill
  4. Cycle vs Runner: ??
44
Q

Process

A

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