6. Biomechanics Flashcards
(42 cards)
What is Biomechanics?
Biomechanics -
the application of mechanical laws to living structures, specifically to the locomotor system of the human body.
What are some Applications of Biomechanical Analyses? (8)
! Improvement of sports skill techniques
! Design of sports equipment
! Prevention of injuries
! Clinical analysis of movement pathologies
! Design of prostheses
! Design of rehabilitation devices
! Animation for film and video games
! Ergonomic redesign in the workplace
What is Qualitative movement analysis?
a non-numerical description of a movement based on direct observation.
– Conducted primarily by teachers and coaches.
What is Quantitative movement analysis?
a movement is analyzed numerically based on measurements from data collected during the performance of the movement.
– Conducted by researchers.
What is Pressure?
What is Compression?
What is Tension?
Compression - pressing or squeezing force directly axially through a body
Tension – pulling or stretching force directly axially through a body
What is Shear?
Shear – force directed parallel to a surface
What is Mechanical Stress?
Mechanical stress = F/A Similar to pressure
What are the LEVERS of the human body?
A lever is defined as a rigid bar that turns about an axis.
In the body, the bones represent the bars and the joints are the axes. Contraction of the muscles provides the force to move the levers
What are The three parts of a lever?
(FRA)
– The force point (F) —
The exact point where the effort is applied. (muscle insertion)
– The resistance point (R) —
The exact point on which the resistance acts. (segment plus external weight)
– The fulcrum (A) — The axis of motion.
What is the Force Arm? (FA)
The force arm (FA) of a lever is the perpendicular distance from the fulcrum to the line of action of the force acting on the force point.
What is the Resistance Arm? (RA)
The resistance arm (RA) of a lever is the perpendicular distance from the fulcrum to the line of action of the resistance acting on the resistance point.
What is a First-Class Lever?
A first-class lever has its fulcrum at some location between the force point and the resistance point
– A typical example of a first-class lever is a teetertotter or seesaw.
What is a Second-Class Lever?
– Second-class levers have their resistance point at some location between the force point and the fulcrum.
– The wheelbarrow is a good example:
– the wheel is the fulcrum
– the weight sitting in the box is the
resistance point
– and the handle is the force point.
What is a Third-Class Lever?
– A third-class lever has its force point at some location between the resistance point and the fulcrum.
– most common in the body,
– it permits the muscle to be inserted near the joint and produce distance and speed of movement
– although at a sacrifice of force.
What is THE MECHANICAL ADVANTAGE OF LEVER?
The mechanical advantage of a lever –
the ratio of force arm length to resistance arm length
* The efficiency with which a lever is able to magnify forces are described by its mechanical advantage (MA) or mechanical ratio.
What is a Force Lever?
Whenever the force arm (FA) of a lever is longer than its resistance arm (RA), the mechanical advantage favours the application of force at the sacrifice of speed, and the lever is called a force lever.
What is a Speed Lever?
Conversely, when the resistance arm is longer than the force arm, the lever favours speed and range of motion at the sacrifice of force and is called a speed lever
Mechanical Advantages of First-Class Levers?
Mechanical Advantages of Second-Class Levers and Third-Class Levers?
What is the Moment Arm?
Moment arm –
the perpendicular distance between the force’s line of action and the axis of rotation.
What is Torque?
Torque –
the product of force and the perpendicular distance (moment arm) from the force’s line of action to the axis of rotation. It may be thought of as a rotary force.
How to Lift A Heavy Object From the Floor (8)
- GET HELP, Use techniques that minimize the
actual weight of the load being handled. - Face the object, feet flat on the floor, at shoulder width, and pointing straight ahead. Ensure that you have a STABLE BASE of support so that you don’t slip as you are lifting the load.
- Face the object in the DIRECTION in which you intend to move with it so that you don’t have to turn. Avoid twisting
- Keep the object as CLOSE to your body to minimize the reaction torque on the low back
- Get a good GRIP
- Bend at the knees and hips and keep your BACK as STRAIGHT as possible. Avoid a fully flexed or bent spine.
- Lift the object using the KNEE and hip extensor muscles, not by pulling upwards with the arms and back.
- Carry the object close to your CENTER OF GRAVITY
Tips for Lifting Heavy Box (5)
- Flat Back > Round Back
(minimizes ligament strain, L5/S1 disc) - Avoid Full Flexion of the Trunk
(decreases probability of disc herniation) - Stand for a Brief Period (not walk)
- Contract Core Muscles
- Avoid Lifting after rising from bed
