Biomechanics and Force Fundamentals

Vocabulary terms covering basic biomechanical concepts, scalar and vector quantities, and types of forces including gravity and friction.

Biomechanics

Mechanics applied to the human body.

Musculoskeletal (MS) system

The internal system that produces human movement.

Mechanics

The field used to describe the function of the musculoskeletal (MS) system.

Scalar quantity

A quantity that has magnitude only, such as speed ($MPH$), length ($X$# of $ft$), area ($X$# square $ft$), volume ($X$ cubic $ft$), and mass ($lbs$, kilos).

Vector

A quantity that has both magnitude and direction, such as force, velocity, and acceleration.

Magnitude

In a vector, it indicates the amount of a measurement (e.g., $10\,lbs$).

Direction

In a vector, it indicates the direction in which the magnitude is applied (e.g., elbow flexion).

Force

The amount of push or pull applied to objects or body segments.

Push

A type of force that creates compression.

Pull

A type of force that creates traction.

Internal forces

Forces that include muscle contraction, ligamentous restraint, and bony support.

External forces

Forces including gravity and any externally applied resistance such as weight or friction.

Gravity

The mutual attraction between the earth and an object.

Gravitational force

The force exerted on an object or person by gravity.

Weight

The relationship of a gravitational force and the mass of an object which always pushed directly downward.

Ground reaction force

The upward force a supporting surface exerts when an object pushes downward on the supporting surface.

Friction

The force between two surfaces that increased resistance to motion of one surface across another.

Compression (in relation to friction)

Increases friction and makes movement more difficult.

Traction (in relation to friction)

Decreases friction and makes movement easier.