Lecture 1 - Introduction to Biomechanics Flashcards
What is biomechanics?
The science of movement of the living body
What is kinematics?
The study of motion without regard to forces that cause that motion
What is kinetics?
The study of motion under the action of forces
What are the planes of movement?
- Sagittal
- Frontal/coronal
- Transverse
What are the axes of movement?
- Anterior/posterior
- Longitudinal
- Medial/lateral
What axis does the sagittal plane move about?
Mediolateral axis
What axis does the frontal plane move about?
Anteroposterior axis
What axis does the transverse plane move about?
Longitudinal axis
What is the global coordinate system?
- Fixed to a point in space
- 3 dimensions (x, y, z)
- Choice of origin and initial position are crucial
- Useful for functional activities
What is the anatomic coordinate system?
- Fixed to a rigid body
- Two local coordinates compared to determine joint angles
- Useful for understanding joint function and ROM
What are the two types of movement?
- Translation: all points on an object move the same distance
- Rotation: one point on the object remains stationary
What are the kinematic variables?
- Position
- Displacement: distance between two locations
- Velocity: change in distance over time
- Acceleration: change in velocity over time
What are the degrees of freeedom?
How many ways something can move
What are 6 degrees of freedom of movement?
- Six ways to move in a 3D space
- Translate along 3 axes or rotate about 3 axes
What causes less than 6 DOF in joints?
Constraints (exp: joint surfaces, ligaments)
What is force (F)?
- A push/pull acting on a body (F = m x a)
- Measured in Newtons (N)
- Exp: Muscles, ligaments, ground reaction, weight
What are inertial forces?
Forces due to acceleration
What is moment/torque (M)?
- Force acting to rotate an object
- Both magnitude, direction and distance from center of rotation are important
What is work?
The force required to move an object a distance (W = F x d)
What is power?
The rate that work is being done (P = W/t)
Example: The snatch vs The clean and jerk
Which requires more power -> The snatch (less time to complete = more power required)
What is energy?
- Potential energy: stored energy
- Kinetic energy: energy of motion
What is anthropometry?
- The study of physical measurements of the human body.
- Measures: segment length and mass, center of mass location and radius of gyration
What are Newton’s Laws?
1st law: an object remains at rest unless acted upon by an external force (∑F=0 and ∑M=0)
2nd law: if there is an unbalanced force acting on an object, it produces an acceleration in the direction of the force (F = m x a)
3rd law: for every action, there is a reaction (opposing force) of equal magnitude in the opposite direction
What are free body diagrams?
- Tool for analyzing biomechanical events
- Used to show all forces acting upon an object
- Arrows show the direction that the force is acting
What is a lever?
A rigid body with two externally applied forces and a point of rotation
What are the parts of a lever?
- Force arm: perpendicular distance from the axis to the line of action of the force
- Resistance arm: perpendicular distance from the axis to the line of action of the resistance
What are the classes of levers?
1st class: forces on different sides of the fulcrum
2nd class: forces on the same side of the fulcrum and the external force is closer to the fulcrum than the muscle force
3rd class: forces on the same side of the fulcrum and the muscle force is closer to the fulcrum than the external force
FLE 123
How does the lever system of the elbow work?
Flexion:
- 3rd class lever
- Effort comes from the point of insertion of the biceps
Extension:
- 1st class lever
- Effort created by the triceps via insertion point on the ulna
