Lecture 2

Question 1

What is biomechanics?

Answer 1

Integrative discipline that applies the principles of mechanics to living organisms…
- Physics
- Anatomy & Physio
- Mechanical Engineering
Used to understand normal and pathological motion, physical performance, and MOI

Question 2

Kinematics

Answer 2

Study of Movement

Question 3

Types of motion: Kinematics

Answer 3

Translation (linear, gliding)
Rotary (rotational; elbow f)
Curvilinear (combo; knee f/e)

3 planes of motion

Question 4

Direction of motion: Kinematics

Answer 4

Flexion/Extension
Abduction/Adduction
Medial/Lateral Rotation

Question 5

Quantity of Motion: Kinematics

Answer 5

Translational: meters
Rotary: degrees
Velocity: Linear, Angular

Question 6

Kinetics

Answer 6

Branch of mechanism dealing with the analysis of forces

Question 7

Statics: Kinetics

Answer 7

Study of forces acting on a system when NO motion is occurring
- Equilibrium (rest/constant)

Question 8

Dynamics: Kinetics

Answer 8

Study of forces acting on a system when motion is occurring

- Causing object to move out of equilibrium

Question 9

Force

Answer 9

A physical quantity that can cause a change in position or alter the direction or speed of rotation of n object
F=Ma

Question 10

Vector Quantity: Force

Answer 10

Point of Application
Direction
Magnitude

Question 11

Forces Imparted to the Floor During Gait

Answer 11

- Caused by falling BW or muscle action
3 principle forces
1) downward (vertical), body
2) medial/lateral
3) anterior/posterior, foot contact

Question 12

Newton’s 3rd Law

Answer 12

For every action (force) there is always an equal and opposite reaction

Question 13

Joint reaction force

Answer 13

Force equal and opposite to one bone acting on another (tibia/femur)

Question 14

Ground reaction force

Answer 14

Force equal and opposite to the force acting on the ground

Question 15

Resultant GRF Vector

Answer 15

Vector sum of the 3 components of the GRF
Qualities:
1) Magnitude, length of vector
2) Point of Origin - COP
3) Direction - towards COM

Question 16

Center of Pressure (COP)

Answer 16

Location of the average WB force (origin of GRF)
Influenced by movement of COM
Commonly used as an indicator of postural stability

Question 17

Pressure

Answer 17

A physical quantity that is a force spread over a given area (P=Force/Area)

Question 18

Torque/Moment

Answer 18

Force that causes rotation about an axis

Torque (moment) = Force x Lever Arm

Question 19

Lever Arm

Answer 19

Perpendicular distance form the line of force to the axis of rotation

Question 20

External Torque

Answer 20

Rotational potential of forces outside of the body acting on a joint
GRF
Gravity

Wins = eccentric

Question 21

Internal Torque

Answer 21

Rotational potential of forces acting within the body acting on a joint
Muscle forces

Wins = concentric

Question 22

Support Moment

Answer 22

Sum of the sagittal plane moments at the ankle, knee, and hip
Total LE demand required to support the body during WB

Question 23

Knee strategy

Answer 23

Movement behavior that bias a particular joint/group, this case the quads
The furthest joint away from GRF is the muscle group that works the hardest

Question 24

Hip strategy

Answer 24

Hip extensors further from GRF, this works the hip extensors

Question 25

Do trunk position influence hip & knee moments?

Answer 25

YES

Question 26

Backward trunk lean

Answer 26

• Hip flexion moment, decrease glut max/hs
• Knee flexion moment, increase quads
• Ankle PF, increase dorsiflexors