BioMech

Question 1

What is EMG?

What does it record?

What does it measure?

Answer 1

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

Question 2

Terms:
Descending Drive
Motor Neuron
Motor Unit

Answer 2

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

Question 3

4 Main Parts of Neuron/What they Do?

Answer 3

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

Question 4

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

Answer 4

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

Question 5

Layers of a muscle

Little description of each

Answer 5

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)

Question 6

sEMG vs iEMG
What?
Pros and Cons

Answer 6

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

Question 7

What are some factors affecting sEMG

Answer 7

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

Question 8

Sliding filament theory
What is it?
What are the layers

Answer 8

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)

Question 9

EMG prep

Answer 9

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

Question 10

Processing Data

Answer 10

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

Question 11

Run down of AP

Answer 11

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

Question 12

Two types of EMG arangements

Types of EMG

Answer 12

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

Question 13

3 Areas to use EKG

Answer 13

Sport
Infer force. Problems. Identify fatigue. Optimal exercise

Medicine
Diagnose. Rehab. Abnormal

Ergo
Posture. Risk. Ergo Design

Question 14

Electircal potnential

Answer 14

Diff of charge carried across membrane

Question 15

Saltatory conduction

Answer 15

Notes of ranvier and their importance

Question 16

EMD

Answer 16

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

Question 17

How to charcterize muscle

Answer 17

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

Question 18

Decending drive

Answer 18

Info from brain to spinal

Question 19

MU

Answer 19

@motor neuron and all the muscles it inervates

Question 20

RMP

Answer 20

Neuron @ no signal. AKA Steady state minus leakage .

Question 21

EMD

Answer 21

Electro Mechnaical Delay

Question 22

Saltatory Conduction

Answer 22

Skipping the mylen sheath

Question 23

Electrical potential

Answer 23

Differences of charge carried across membrane

Question 24

Heneman’s 2 Theory

Answer 24

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

Question 25

Draw F/V or Movement Velo

Answer 25

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

Question 26

EMG Force relationship

Answer 26

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

Question 27

Fatiuge

Answer 27

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

Question 28

Twitch occlusion equation

Answer 28

ST/PT X 100 = % innactive

Question 29

2 Areas of Fatiuge

Answer 29

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

Question 30

Asses Fatiuge with EMG

Answer 30

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

Question 31

Quatify Fatiuge

Answer 31

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

Question 32

Age

Answer 32

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

Question 33

Sex Differences

Answer 33

1. Mass 2. Morphology 3. Substrate utilization 4.NMJ Activation

Question 34

Muscle Characteristics

Answer 34

1. Lengthen 2. Shorten 3. Excitable 4. Elastic

Question 35

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

Answer 35

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

Question 36

Muscle Shapes and Organizations

Answer 36

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

Question 37

Two types of CSA and a few points on each Whats the PSCA Equation

Answer 37

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

Question 38

Actin and Myosin Bands/Lines/Zones

Answer 38

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

Question 39

Volume or Area is a greater contributor to muscle force? Discuss

Answer 39

Area Long muscles have more velo, Shorter have more force. Short and thick = force /\

Question 40

What is pennation angle

Answer 40

Angle of muscle fibre and line of pull

Question 41

Hill muscle model components Draw the force length relationship.

Answer 41

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

Question 42

3 Muscle FXN

Answer 42

1. Stabilize 2. Produce movement 3. Posture Others? Heat, support, control

Question 43

4 Examples of Muscle Plasticity

Answer 43

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: ??

Question 44

Process