- Base of Support
This is where your body comes into contact with the supporting surface. For example,
when standing the base of support is the total area around, and in between your feet. Sitting in a
chair, the base of support is the area between your feet and your buttocks.
- Balance
The act of keeping your center of gravity over your base of support.- Stability
Ability to keep the center of gravity over the base of support. The closer the center of
gravity is to the base of support, the more stability one will have. An example would be the biceps
curl, when the load moves forward and the body moves back in order to find the center of gravity.
- Equilibrium
This is the act of keeping your center of gravity near your base of support and restraining
from moving beyond your center of support.
- Force
A force is a push or a pull on a given point, of given magnitude, in a given direction.
Force either produces or prevents motion, and a visible change in motion need not occur
when a force is applied. This means that a force can be applied to an immovable object. The
magnitude of muscular forces can be described in terms of “strength,” and can be measured
using dynamometers, tensiometers, and strain gauges. A rough estimate of muscular force is
85 to 186 lb/in^2. When muscles contract, the point of application is found at the attachments of
the muscles, and the direction of the muscular force usually runs from the insertion of a muscle
toward its origin. In terms of center of gravity, a reaction force acts on the center of gravity. An
example would be cable crossovers; leaning forward to stabilize to prevent being pulled back
Any quantity, such as a force, which has a point of application, a magnitude, and a
direction, is called a vector quantity. This can be depicted as a muscle’s insertion (point of
application), and the muscle’s origin (typically the where the direction of pull is applied to), and
the muscular contraction itself (force being applied by the muscle).
- Vector: has point of application, magnitude and direction.
- Resultant: put two vectors together. To measure take the bottom vector and move it to
the top then draw line to original point. - Displacement: change in position.