Kinesiology and Biomechanics - Vocabulary Flashcards

09/03/25 - AI Generated

Kinesiology

The study of human movement through anatomy, physiology, physics, and mechanics.

Biomechanics

Application of mechanical principles to biological systems; analyzes motion and the forces that produce it.

Kinematics

Description of motion without regard to forces (position, direction, speed, and displacement).

Kinetics

Study of the effects of forces and torques on the body.

Motion

Any change in position of a body over time.

Displacement

Change in position; a vector from the starting point to the ending point.

Rotary/Angular Motion

Movement around a fixed axis; different parts rotate through the same angle at the same time.

General Motion

Combination of rotation and translation; includes curved paths.

Curvilinear Motion

Motion along a curved, non-circular path.

Axis

A fixed line about which rotation occurs; the pivot point for rotation.

Line of Action

The straight path along which a force acts; direction and angle; magnitude represented by length.

Vector

A quantity with both magnitude and direction; force vectors have a base, direction, and magnitude.

Force

A push or pull that initiates, modifies, or stops movement.

Gravity

Mutual attraction between Earth and an object; gravitational force acts downward (g ≈ 9.8 m/s^2).

Weight

Gravitational force acting on an object's mass.

Line of Gravity (LOG)

The vertical line along gravity through the body; used to assess stability (projection of gravity).

Center of Mass (COM)

The point at which the total mass of a body can be considered to be concentrated; location of balance.

Center of Gravity (COG)

The point where the entire weight of a body acts; position of balance in the body.

Ground Reaction Force (GRF)

Upward force exerted by a supporting surface; equal and opposite to the component of body weight during contact.

Base of Support (BOS)

The area beneath and between the body’s points of contact with a support surface.

Stability

Resistance to tipping or sliding; depends on BOS, location of COG/LOG within BOS, mass, and friction.

Internal Forces

Forces generated from within the body (e.g., muscles, connective tissues).

External Forces

Forces acting from outside the body (e.g., gravity, ground reaction).

Joint Reaction Forces (JRFs)

Resultant forces transmitted across joints between adjacent segments.

Newton’s First Law (Law of Inertia)

An object remains at rest or moves at a constant velocity unless acted on by an external force.

Newton’s Second Law (F = ma)

Acceleration of an object is proportional to the net applied force and inversely proportional to its mass.

Newton’s Third Law (Action-Reaction)

For every action there is an equal and opposite reaction.

Momentum

Mass × velocity; external force is required to change momentum.

Torque

The tendency of a force to produce rotation about an axis.

Moment Arm (MA)

Perpendicular distance from the axis to the line of action of the force.

Torque Equation

Torque (T) = Force (F) × Moment Arm (MA).

Force Couple

Two or more parallel forces in opposite directions that produce rotation without translation.

Anatomic Pulley

A tendon or muscle path deflected by bone to change the line of pull and increase torque.

Pulleys

Structures that redirect force to alter the line of pull (e.g., around a bone or prominence).

Mechanical Advantage (MA)

The ratio of load moved to effort exerted; MA increases with longer effort arm.

Lever

A rigid bar that rotates about a fulcrum (axis) when forces are applied.

Fulcrum (Axis)

The pivot point about which a lever turns.

Force Arm (FA)

Distance from the axis to where the force is applied.

Resistance Arm (RA)

Distance from the axis to the resistance (load).

First-Class Lever

Axis is between the force and the resistance.

Second-Class Lever

Resistance is between the axis and the force; mechanical advantage > 1.

Third-Class Lever

Force is between the axis and the resistance; mechanical advantage < 1.

Friction

Resistance to motion between two surfaces; increased by compression, decreased by traction.

Velocity

Speed with direction; velocity = distance/time.

IMA (Internal Moment Arm)

Perpendicular distance from the axis to the line of action of the internal force.

EMA (External Moment Arm)

Perpendicular distance from the axis to the line of action of the external force.