Lecture 2 Flashcards
What is biomechanics?
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
Kinematics
Study of Movement
Types of motion: Kinematics
Translation (linear, gliding)
Rotary (rotational; elbow f)
Curvilinear (combo; knee f/e)
3 planes of motion
Direction of motion: Kinematics
Flexion/Extension
Abduction/Adduction
Medial/Lateral Rotation
Quantity of Motion: Kinematics
Translational: meters
Rotary: degrees
Velocity: Linear, Angular
Kinetics
Branch of mechanism dealing with the analysis of forces
Statics: Kinetics
Study of forces acting on a system when NO motion is occurring
- Equilibrium (rest/constant)
Dynamics: Kinetics
Study of forces acting on a system when motion is occurring
- Causing object to move out of equilibrium
Force
A physical quantity that can cause a change in position or alter the direction or speed of rotation of n object
F=Ma
Vector Quantity: Force
Point of Application
Direction
Magnitude
Forces Imparted to the Floor During Gait
- Caused by falling BW or muscle action 3 principle forces 1) downward (vertical), body 2) medial/lateral 3) anterior/posterior, foot contact
Newton’s 3rd Law
For every action (force) there is always an equal and opposite reaction
Joint reaction force
Force equal and opposite to one bone acting on another (tibia/femur)
Ground reaction force
Force equal and opposite to the force acting on the ground
Resultant GRF Vector
Vector sum of the 3 components of the GRF Qualities: 1) Magnitude, length of vector 2) Point of Origin - COP 3) Direction - towards COM
Center of Pressure (COP)
Location of the average WB force (origin of GRF)
Influenced by movement of COM
Commonly used as an indicator of postural stability
Pressure
A physical quantity that is a force spread over a given area (P=Force/Area)
Torque/Moment
Force that causes rotation about an axis
Torque (moment) = Force x Lever Arm
Lever Arm
Perpendicular distance form the line of force to the axis of rotation
External Torque
Rotational potential of forces outside of the body acting on a joint
GRF
Gravity
Wins = eccentric
Internal Torque
Rotational potential of forces acting within the body acting on a joint
Muscle forces
Wins = concentric
Support Moment
Sum of the sagittal plane moments at the ankle, knee, and hip
Total LE demand required to support the body during WB
Knee strategy
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
Hip strategy
Hip extensors further from GRF, this works the hip extensors
Do trunk position influence hip & knee moments?
YES
Backward trunk lean
- Hip flexion moment, decrease glut max/hs
- Knee flexion moment, increase quads
- Ankle PF, increase dorsiflexors
