Biomechanics as it applies to movement and injury Flashcards
Kinematics
Description of movement without reference to the forces that causes the motion.
Linear kinematics
Movement of a point. For example, the displacement, velocity and acceleration of a body. A runner, a swimmer or a high jumper for example. Linear movement is measured or quantified in one dimension (x, y, z – horizontal, vertical or depth) and each direction from the origin has a sign (+ or -)
Angular kinematics
“Angular” refers to joint angles. An angle is the space (usually measured in degrees) between two intersecting lines. In the body, the bones are the lines and the intersection is the joint
Position:
Where the point of interest is relative to a reference frame (origin).
Displacement:
The change in position of an object. (d = pf-pi)
Velocity:
Displacement divided by time over which displacement occurs.
Acceleration:
The rate of change in velocity; the change in velocity over time.
Angular Position
What is the angle between two lines? That is the angular position. Notice that there is no coordinate system and no horizontal or vertical orientation.
Let’s agree on the following convention:
+ clockwise
- counterclockwise
Angular Displacement:
The difference between the end position angle and beginning position angle when you have pictures at two different time points
Angular Velocity:
The rate at which the angle changed
Angular Acceleration:
The rate of change of velocity
Kinetics:
Analysis of movement considering the forces involved to explain the movement. Without forces, movement wouldn’t happen! Forces are the push or the pulls that cause movements.
Linear kinetics:
we consider all of the forces acting on one point to explain the movement. This is where we used free-body diagram. Some of the terminology you should feel comfortable using include:
Force: A push or a pull (energy) applied to a system.
Mass: The amount of inertia of a system (object/body).
Momentum: The quantity of motion of a moving body. It is measured as a product of its mass and its velocity.
Inertia: A body’s resistance to motion.
Mechanism of injury
Injuries happen when there is too much energy loaded into a tissue. The force or strain acts on the tissue in different ways depending on the properties of the material but each tissue has a toe region, elastic region, plastic region and failure point.
