Week 13 - Activity analysis and levers Flashcards
What is the function of a frame of reference?
Frames of reference guide practice by delineating the beliefs, assumptions, definitions, and concepts within a specific area of practice.
How can biomechanics be used as a frame of reference?
Biomechanics is a useful frame of reference that can be applied to purposeful activities in rehabilitation.
What are the strengths of using a biomechanical frame of reference and activity?
- Facilitates evaluation of movement in activity
- Can help in developing adaptive equipment and exercise or activity programs to restore function often related to a specific body part.
What are the limitations of using a biomechanical frame of reference and activity? (2)
What is the solution?
- Does not address the cognitive, social or psychological aspects of activity
- Often the focus is on one part of the body and not the whole person
Solution: imbedded in a larger model
What are the rehabilitation settings where biomechanical analysis of activity?
- Hand Clinics
- Work Hardening
- Research
- Rehabilitation centers
- Ergonomics
What is a lever?
What is it composed of?
A bar (or rigid body) rotating around an axis.
It is composed of a moving force (effort), an axis (fulcrum) and a resistive force (load).
See NDC p.17 for illustration
What is a force arm?
–> Effort
The perpendicular distance from the axis to the line of action of the force.
What is the resistance of the arm?
The perpendicular distance from the axis to the line of action of the resistance.
What is the formula for mechanical advantage?
Mechanical advantage = Force (Effort) arm / Resistance arm
See NDC p.19 for example
Woman lifting baby.
How to increase mechanical advantage?
Resistance = baby
Resistance arm = distance between axis (shoulder) and baby
So if we reduce the distance (keep resistance close) = better mechanical advantage
What are the classes of levers?
- First Class Lever
- Second Class Lever
- Third Class Lever
See NDC p.21, 30 for illustration
What is a first class lever?
Axis located between the two forces
–> ex: see-saw
See NDC p.21 for illustration
What is a second class lever?
Axis at one end.
Resistance closest to axis. RA˂ FA.
–> ex: wheelbarrow
More control, less force
See NDC p.21 for illustration
What is a third class lever?
Axis at one end.
Force closest to axis RA ˃FA.
–> ex: Biceps
Most levers in the human body are third class: more force, less control
See NDC p.21 for illustration
See NDC p.21-26 for lever identification example + p.30 for illustration
