Basic Biomechanics

Question 1

Movement is governed by…

Answer 1

physical laws

Question 2

To assess movement we can…

Answer 2

• measure it
• use our senses (i.e. watching someone walk)

Question 3

Biomechanics can be used in orthopedics for probing…

Answer 3

• acute injury mechanisms (e.g. ACL injury)
• chronic injury pathophysiology (e.g. tendinopathy)
• surgical options (e.g. how long a hip replacement surgery will last)
• adaptation vs. maintenance (i.e. figuring out what force will cause mechanotransduction and what force will create injury)

Question 4

Biomechanics can be used in rehab for…

Answer 4

1. fitting devices:
   - gait-supportive orthotics to augment abnormal neuromuscular function
   - assistive devices
   - prosthetics
2. predicting therapeutic changes to movement for chronic disease (e.g. stoke)

Question 5

Biomechanics can be used for motor learning/control in helping us to…

Answer 5

find the line between improving sport performance and possible injury risk

Question 6

Other applications for biomechanics

Answer 6

• MVAs (i.e. understanding force going through body during accident)
• cardiorespiratory mechanics
• fracture modelling (used in return to play decisions)
• robot assisted surgery (i.e. training robots to practice safe movements during surgery)

Question 7

biomechanics - definition

Answer 7

the use of mathematics and physical principles, to study and understand movement

Question 8

kinematics - definition

Answer 8

• what happened
• the study of movement w/o regard to the forces that cause that movement (what we see)

Question 9

kinetics - definition

Answer 9

• how did it happen
• the study of the forces causing movement (how it happens)

Question 10

osteokinematics

Answer 10

• movement between bones
• what position / angle is a bone in at a certain point in time
• looking at segment or joint angles (describes the motion we see)

Question 11

Sagittal plane movements

Answer 11

• flexion/extension

Question 12

Sagittal plane splits you into…

Answer 12

left and right sides

Question 13

Sagittal plane - At which axis do joints rotate in

Answer 13

mediolateral

Question 14

which movements happen in the frontal plane?

Answer 14

• abduction, adduction

Question 15

Frontal plane - At which axis do joints rotate in

Answer 15

anteroposterior

Question 16

Transverse plane - At which axis do joints rotate in

Answer 16

inferosuperior

Question 17

which movements occur in the transverse plane?

Answer 17

internal and external rotation

Question 18

transverse plane cuts ____________ body

Answer 18

across (divides into superior and inferior portions)

Question 19

frontal plane divides the body into…

Answer 19

anterior and posterior portions

Question 20

segment vs. joint angle

Answer 20

segment angle= angle of a body segment (like a thigh or forearm) relative to a reference line, such as a horizontal or vertical axis
- absolute angle

joint angle= angle b/w 2 segments (e.g. b/w tibia and fibula)
- relative angle

Question 21

Kinematics - ways to describe movement

Answer 21

position: linear-> meters; angular-> degrees or radians

velocity: linear-> m/s; angular-> deg/s or rad/s

acceleration: linear-> m/s squared; angular-> deg/s squared or rad/s squared

Question 22

Linear Kinematics describes motion…

Answer 22

along a straight line or path

Question 23

Angular Kinematics describes rotational motion…

Answer 23

around an axis

Question 24

Linear Kinetics are described in terms of …

Answer 24

forces (newtons)

Question 25

Angular Kinetics are described in terms of ...

Answer 25

moments (newton-meters)

Question 26

force =

Answer 26

- a push or a pull - can cause both linear and angular motion depending on where force is applied -> rotation will occur if there is a fixed point (axis of rotation) on an object (force pushes/pulls somewhere other than that point, causing rotation )

Question 27

Newton's laws - 1st law

Answer 27

law of inertia: a body will remain at rest or in constant motion unless acted on by external force

Question 28

Newton's laws - 2nd law

Answer 28

law of acceleration: linear or angular acceleration is - inversely proportional to the mass - proportional to the unbalanced forces on the object

Question 29

Newton's laws - 3rd law

Answer 29

every action has an equal and opposite reaction

Question 30

to get angular motion, a force must be applied...

Answer 30

at a distance from the point of rotation

Question 31

larger moment from ...

Answer 31

- larger force - larger moment arm

Question 32

the moment arm=

Answer 32

the perpendicular distance from the line of action of the force application to the axis of rotation

Question 33

internal forces

Answer 33

forces that arise from inside the body - muscles - tendons - ligaments and joints capsule - friction

Question 34

isometric contraction

Answer 34

muscle is active but no movement ; e.g. holding a food tray in hand

Question 35

concentric contraction

Answer 35

muscle is active and shortening (there is movement)

Question 36

eccentric contraction

Answer 36

muscle is active and lengthening (there is movement); e.g. holding a really heavy weight with an extended arm

Question 37

internal forces (or moments) relative to external forces (or moments) dictate

Answer 37

possible linear/angular motion - there needs to be a difference b/w the two for there to be movement (otherwise it will be isometric)

Question 38

external forces

Answer 38

forces acting from outside the body, to the body - point of application - direction (pull or push) - magnitude (how big is it?)

Question 39

with more mass concentrated at a greater distance from the center of rotation=

Answer 39

larger moment of inertia

Question 40

an object of rotational inertia will angularly accelerate proportional to _______________ and inversely to __________________

Answer 40

- the moment (M) applied to it - its rotation inertia

Question 41

inertia =

Answer 41

the rotational equivalent of mass (bigger inertia= harder to rotate)

Question 42

joint position changes...

Answer 42

- moments, and ... - muscle force (due to varying myofilament overlap)

Question 43

Forces cause...

Answer 43

tissue changes; - tissue is malleable to a point but beyond this, irreparable change or failure occurs (e.g. achilles tendon or ACL ruptures)

Question 44

We have a minimum stress required to create tissue adaptations... and a ________________________

Answer 44

maximal adaptation capacity

Question 45

Maintaining our level of daily stress between the minimum stress required to create adaptations and the maximum capacity for adaptation will slowly

Answer 45

increase the body's capacity to sustain mechanical stress

Question 46

If we repeatedly stress our tissues above the maximal adaptation capacity

Answer 46

- danger zone! - potential for pain, injury, overuse - could be instantaneous tissue failure - plastic zone

Question 47

the elastic zone encompasses ...

Answer 47

when stress applied is less than maximal adaptation capacity (whether below or above minimum stress required to create adaptations)

Question 48

the slope of the stress-strain curve is...

Answer 48

tissue stiffness

Question 49

We each have our own stress/strain (maximum capacity) curve based on our individual...

Answer 49

- training/detraining - age - injury history - overall health - environment (weather, surface etc)

Question 50

linear forces can create...

Answer 50

angular movement (there is always an axis of rotation) *muscles create linear forces that create movement

Question 51

internal sources of forces

Answer 51

skin, ligament, bone, fascia, muscle/tendon

Question 52

external sources of forces

Answer 52

gravity, contact forces, GRF, wind resistance

Question 53

moment components

Answer 53

force = internal and external moment arm = internal (origin/insertion and joint position) and external (direction, body position)