AMC Sem 2 Flashcards

Question

Isometric force production variation

Answer 1

If told to hold a set force typically remain in right area with some slight fluctuations

Answer 2

Complete intermittent contractions until task failure Perform MVC every 1 min The fall in the MVC is a measure of fatigue

Answer 3

Exercise induced processes reducing force proximal to NMJ - Brain/CNS/PNS effected

Answer 4

Exercise induced processes reducing force at or distal to NMJ - muscle fatigue

Answer 5

Apply stimulus during contraction If maximally activated the twitch shouldn’t increase output

Answer 6

Stimulus is applied at rest - no input from CNS Gives idea of muscle capacity Peripheral fatigue results in reduced resting twitch

Answer 7

Voluntary activation = (1-a/b x 100) a = superimposed twitch b = resting twitch

Answer 8

Use muscle stimulator Can be per cutaneous or femoral nerve (better but less comfortable)

Answer 9

EMG is reduced Submaximal EMG is increased to compensate for peripheral fatigue

Answer 10

If above critical torque get progressive neuromuscular fatigue

Answer 11

2 bouts exercise below torque + 2 bouts above torque Below showed some progressive fatigue but able to continue for whole hour Above - v significant fatigue, task failure within 15-20 min, had to use MVC to achieve desired force by the end

Answer 12

Key fatigue threshold for peripheral fatigue

Answer 13

No, metabolic rate cannot be stabilised above the CT therefore progressive reductions in torque complexity should only occur above CT

Answer 14

Peripheral body eg muscles as no loss of complexity occurs below CT

Answer 15

1. Exercise to task failure 2. Group 1 allowed 3 min recovery, group 2 use cuff to occlude + prevent recovery When no recovery occurs complexity remains low but complexity increases during recovery

Answer 16

Ingest either 6mg/kg caffeine or placebo Caffeine prevented fall in neuromuscular complexity but no change in fatigue level Suggests complexity plays a small but significant role in complexity

Answer 17

Active control of physical shape of limbs to provide varying degrees of passive stability + muscular actions to provide compensatory active stability for passive insufficiencies

Answer 18

Tendency for body to remain in or return to its initial position following application of force. Can be passive or dynamic

Answer 19

Impossible for body to remain completely still - passive instability - muscle errors -sensory errors -feedback delays -control strategies

Answer 20

Likely to return to stable state following small perturbations

Answer 21

Small perturbation cause centre of gravity to move more easily

Answer 22

Weight - more mass = harder to accelerate/ be knocked Area of base - more area = more stable Horizontal distance of centre of gravity to pivot point Height of centre of gravity above base - higher = less stable as the more of CoG moves for each 1 degree of movement

Answer 23

Small base of support High CoG above base

Answer 24

Have passive instability so need active muscle contractions to maintain stability Use muscles that cross joints to maintain or regain balance CoG must remain in base of support

Answer 25

Muscles cannot produce perfectly constant force due to variation/error or over/underwhelming force Muscles act across multiple joints and in multiple planes/axis - need to use synergists or other muscles to control/stabilise other body parts

Answer 26

Vision 10% Vestibular apparatus 20% Somatosensory proprioception (Golgi tendon organ/ muscle spindle etc) 70%

Answer 27

Different inputs may cause sensory conflict (what makes you motion sick) Require some movement to work

Answer 28

How much movement is needed for sensory system to say you have moved Really slow movement can’t be detected Really fast movement detected all the time Proprioception has the lowest threshold Vestibule highest threshold need to move quite quick, quite a lot to detect movement

Answer 29

Input - delay- processing- delay output - delay - feedback

Answer 30

Time taken to detect movement Varies based on movement- larger movement = smaller delay

Answer 31

65-130ms Afferent signal transmission - 50ms Descion time - varies Efferent signal transmission- 50ms

Answer 32

13-55ms Time taken from muscle activation til force is produced

Answer 33

Ankle strategy Hip strategy Mixed strategy Arm swing Stepping

Answer 34

Sway about the ankle Controls CoM via ankle torque Most commonly used in quiet stance Fixed hip angle Bad on narrow surface, good with low friction

Answer 35

Use when need to respond quickly Uses more energy but requires less effort Controls CoM by horizontal force Hip angle is opposite to ankle angle Good on narrow surface, bad with low friction

Answer 36

Uses hip and ankle together Often done in practice as allows head to remain up so can still see

Answer 37

Arm swing - when can’t step eg in gymnastics Stepping- to prevent falling

Answer 38

Along where the CoG is in the same position in relation to the ground

Answer 39

Mechanically efficient Easier to control Uses less energy

Answer 40

Expansion of information processing model from engineering Involves model with assumptions- simplification of true system Any variation = unwanted error Add random error to try to simulate humans

Answer 41

Present state of system (position) Quick to correct but leads to overshoot

Answer 42

Past state of system (average over time) Corrects for drift but is slow

Answer 43

Future state of system (current velocity) Prevents overshooting and is similar t dampening

Answer 44

Peterka 2002 used numerous sensory perturbations to determine weights for sensory input - vision 10%, vestibular 20%, proprioception 70%

Answer 45

Simulation output = too good - need to add error or would be perfectly still Relies on excessive noise to reproduce typical postural sway Struggles with latrge delays Can use intermittent control models

Answer 46

It changes the way the whole system evolves, and changes how components in the system are used So may need to use an alternative method to assess the system in its entirety

Answer 47

Variability is a fundamental part of the system not just unwanted noise Movement is integral to perception Sway magnitude is less important Pattern of sway is more important

Answer 48

Loss of information due to reduced order Lower entropy = less loss of information ( easier to predict future)

Answer 49

Periodic signal = low entropy Complex signal = med - high entropy Random signal = high entropy

Answer 50

Measure of local stability of a system Low stability leads to exponential divergence in signal trajectories

Answer 51

Periodic signals - high stability, zero divergence of trajectories Complex signals - some instability, trajectories diverge as time progresses

Answer 52

Entropy and Lyapunov exponent

Answer 53

As child progresses from stage 1 (sitting with support) to stage 3 (independent sitting). Lyapunov exponent decreases as become locally stable Approximate entropy initially decreased and then increased slightly as baby began to explore

Answer 54

Examined postural responses to tracking a moving target Target frequency increased or decreased gradually

Answer 55

Have task constraints, organism constraints and environmental constraints Movement is the product of interaction between these constraints

Answer 56

An ongoing dynamic process driven by constraints It involves- Search of perceptual motor landscape Stabilisation and refinement of functional movement patterns Optimisation of control by exploiting environmental and task information

Answer 57

Strategy used depended on task frequency Hip strategy - anti phase coordination Ankle strategy - in phase coordination Different transaction points showed hysteresis in strategy selection Are reigons of bistability where either strategy is acceptable

Answer 58

Dilated and constricts to let more or less light through

Answer 59

Protective barrier from foreign bodies and UV radiation Initial refraction

Answer 60

Uses refraction and accommodation to focus light on retina

Answer 61

Cones - bright light , coloured central vision Rods - dim light, peripheral vision

Answer 62

Transmits sensory info for vision to the brain in the form of electrical impulses

Answer 63

Use both eyes together, the difference in the angle of light hitting each eye gives important proprioception information

Answer 64

Nasal = nose side Temporal = lateral side Nasal fibres cross over at optic chiasm so info is on the same side

Answer 65

Fixations Saccades

Answer 66

Central visual field (within 3 degrees) 100ms+ duration Conscious processing

Answer 67

Rapid eye movements Between fixations Information is suppressed. Beneficial to work out where something will be + use 1 saccadic to move eyes there than to try + track it using multiple saccades

Answer 68

Aka ventral Used for identification (what?) Central visual field Conscious- takes more time but gives more info

Answer 69

Aka dorsal Optical flow (Where something is) Central and peripheral visual fields Non-conscious - quicker

Answer 70

Optic nerve to occipital lobe Dorsal = occipital lobe to parietal lobe to frontal lobe Ventral = occipital lobe to temporal lobe to frontal lobe Both frontal lobe (response planned) to pre-motor + motor cortex (sequenced and specific movement organised)

Answer 71

Closer objects appear bigger and take up more space on retina - size of something in visual field gives idea of how far away it is

Answer 72

Time to contact (Tau) = size of image/rate of expansion

Answer 73

Use image direction on retina Eg if both sides of a ball are on your left it will be on your left If one side of ball is on either side, it will be hitting you. The less the speed difference between the 2 sides = the wider it will pass

Answer 74

Tau dot Need to couple running speed with rate of change of tau Stop just short - 0.5

Answer 75

Typically slower = more accurate BUT Timing tasks have a reversal of speed accuracy trade off. Easier to intercept at higher speeds as is easier to time

Answer 76

Compared high skilled and low skilled players Occluded sight of ball at various points Pre-bounce occlusion results similar to no occlusion control results Pre-release occlusion results dropped to virtually 0 for low skilled but only 50% for high skilled. Suggests high skilled players use pre-release cues

Answer 77

Elite players tracked ball first 100-200ms, saccade to bounce, then tracked onto bat - allowed longer viewing before and after bounce Low skilled tracked ball first 100-200ms but we’re unable to accurately predict bounce so struggled tracking ball to bat

Answer 78

Vs bowler - things that occur earlier in movement are greater Vs machine -things that occur later in movement eg wrist flick are greater as don’t get visual cues from machine

AMC Sem 2 Flashcards

(104 cards)