memory

Question 1

what to know about low back pain

Answer 1

single leading cause of disability worldwide

prevalence increases with age
-more in women
-peak at 50-55

usually non-specific

cost directly 6-12 billion/year

Question 2

what muscle is typically atrophied in LBP

Answer 2

multifidus

Question 3

define biomechanics

Answer 3

study of the effects of forces acting on living organisms including the effects of these forces on structure and function

Question 4

what is rigid body idealization

Answer 4

A rigid body is an idealized object whose shape and size do not change, meaning the distance between all internal points remains constant.

Question 5

which muscles are being tested in bieiring Sorenson test

Answer 5

hip extensor
erector spinae
multifidus

endurance

Question 6

what type of real life condition is bieiring Sorenson test trying to replicate

Answer 6

trunk posture for lifting tasks

Question 7

what performance can be expected from a healthy adult in bieiring Sorenson test

Answer 7

60-90 s

Question 8

define force + some examples of types of force

Answer 8

a push or pull exerted on one object by another object

gravitational
magnetic
muscle
elastic
machine

Question 9

define moment of a force

Answer 9

torque is another name

the tendency for a force to turn or rotate an object about a point

Question 10

why isn’t torque a rotational force

Answer 10

forces are always linear. rotation is just the product of force on an object

Question 11

explain why mechanical advantage occurs

Answer 11

magnitude of moment may be same but forces could be very different depending on length of moment arm

Question 12

why do muscles exert such large forces compared to resistance

Answer 12

muscles have a very short moment arm while external resistances typically have very large moment arms

Question 13

what is Newton’s first law of motion

Answer 13

law of interia

object a rest stays at rest. objects tend to resist changes in its motion

Question 14

what is a point mass idealization

Answer 14

treat an object as if all of it’s mass is concentrated at a single point in space

object’s dimensions are assumed negligible relative to the scale of the problem

Question 15

what are the conditions for a rigid body to be in static equilibrium

Answer 15

net torque and forces are 0

Question 16

define mass

Answer 16

amount of matter in an object

Question 17

what is centre of mass

Answer 17

average position of all mass of an object

Question 18

what is the difference between Cartesian and polar coordinates

Answer 18

(x,y) (radius, theta)

Question 19

define combined centre of mass

Answer 19

The combined centre of mass is the single point representing the weighted average position of the mass of multiple objects treated as one system.

Question 20

what is a reaction board

Answer 20

assumes static equilibrium

Question 21

how can a reaction board be used to determine COM

Answer 21

COM = sum torque/ total force

Question 22

which types of tasks require combined Com to be over the base of support

Answer 22

static or quasi static tasks

Question 23

which muscles do the squat primarily utilize

Answer 23

monoarticular hip and knee extensor muscles

Question 24

what muscles do the deadlift primarily utilize

Answer 24

hip extensor muscle

Question 25

what is the role of ankle plantar flexors in squat and deadlift

Answer 25

balance

Question 26

what is NJM

Answer 26

net joint moment an estimate of the minimum muscular effort required to perform a task

Question 27

define free body diagram

Answer 27

symbolic representation of an object and the forces acting on it

Question 28

what is newton's third law

Answer 28

for every action (force) in nature, there is an equal and opposite reaction.

Question 29

how is Newton's third law applicable to forces applied to a joint between two rigid bodies

Answer 29

the forces on each rigid body at the joint are equal and opposite. meaning if an object is pushing down on a joint with 5N of force and the joint is not moving then the object below is pushing up with the same force

Question 30

how does an ACL injury affect average peak forces at ankle knee and hip

Answer 30

ankle is unaffected knee decreases in force while hip increases this is called quadriceps avoidance strong quads is the best predictor of successful return to activity after ACL injury

Question 31

explain what a compensatory movement strategy is

Answer 31

musculoskeletal injury may lead to use of compensatory strategies

Question 32

what type of modification to the squat could be useful in equalizing the forces between legs in ACL injury recovery

Answer 32

non involved limb elevated squat

Question 33

what is the limitation for NJM

Answer 33

does not account for co contraction of biarticular muscles

Question 34

why might the moment around a joint be larger than predicted by NJM

Answer 34

co contration of biarticular muscles

Question 35

is the deadlift done at a high level with full lumbar extension?

Answer 35

no. some flexion at high level

Question 36

what is origin and insertion of multifidus

Answer 36

o: s3-l5 I: spinous process 2-4 vertebrae above

Question 37

why is the does the multfidus produce such large moment compared to muscle size

Answer 37

long moment arm resists hip extensor NJM acting on pelvis

Question 38

how does stretching change muscle thickness

Answer 38

increases

Question 39

define muscle strength

Answer 39

the maximal force that a muscle can exert at a particular range of motion at a particular speed

Question 40

why can't true muscle strength be measured in vivo

Answer 40

can't be measured directly. all measures of strength are indirect

Question 41

what are the layers of muscle macrostructure

Answer 41

epimysium muscle belly perimysium muscle fascicle endomysium muscle fibre

Question 42

which part of muscle has a uniform shape compared to all other skeletal muscle

Answer 42

fibres and fascicles. belly can be different but not fibres and fascicles

Question 43

example of triangular muscle

Answer 43

adductor brevus and longus

Question 44

example of strap muscle

Answer 44

sartorius

Question 45

example for fusiform muscle

Answer 45

biceps brachii

Question 46

example of pennate muscle

Answer 46

gastrocnemius

Question 47

what are the 3 types of tendon

Answer 47

tendinous or cord membranous or aponeurotic (flat sheet) fleshy -thing interface between muscle and bone

Question 48

what is the advantage/disadvantage of pennate muscle

Answer 48

same volume greater fascicles greater force generation fascicles are shorter lower contraction speed some force lost due to angle lower contraction distance

Question 49

why is muscle CSA important

Answer 49

related to max muscle force

Question 50

how does pennation angle change with training

Answer 50

increases

Question 51

what are the layers of muscle microstructure

Answer 51

Question 52

describe the force length relationship

Answer 52

4 phases due to sliding filament theory and the optimal interaction between myosin head and actin

Question 53

how does muscle change when adding sarcomeres in series

Answer 53

suppleness/extensibility small or no increase in resting muscle length muscle thickness increases to accommodate longer fascicles no change in max force increase in force at larger and smaller joint angles

Question 54

what is muscle excursion

Answer 54

Muscle excursion is the amount a muscle–tendon unit shortens or lengthens when a joint moves through a range of motion. longer moment arms create greater muscle excursion which leaves it out of optimal length for force production

Question 55

describe newton's second law

Answer 55

a change in motion is proportional to motive force impressed and takes place along a straight line along that force quantity of motion arises from the velocity and quantity of matter

Question 56

what are the three approaches of understanding newton second law

Answer 56

continuously varying forces (f=ma) -mathmatically correct but conceptually difficult to understand impulse momentum (ft=mv) -math is lacking but conceptually useful work energy (w=energy) -conceptually useful and mathematically correct

Question 57

what is vertical jump height

Answer 57

height at takeoff + flight = jump

Question 58

what are the projectile equations

Answer 58

Question 59

what is the difference between static and dynamic equilibrium

Answer 59

both net torque and force 0 dynamic can have velocity or angular velocity static cannot