Kinesiology and Biomechanics: Movement, Forces, and Joint Mechanics

Biokinetics

Study of forces and their effects (static & dynamic)

Biodynamics

Scientific study of the nature and of all organisms behaviour during motion

Kinesiology

Study of the science of human movement and human movement problematics; factors affecting human movement; same as biodynamics but only applies to humans

Kinematics

Study of motion without forces

Kinetics

Study of motion with forces

Flexion & Extension

Movement in the Sagittal Plane about the x-axis

Rotation

Movement in the Transverse plane about the y-axis

Lateral Flexion

Movement in the Coronal Plane about the z-axis

Translation/Linear Motion

Movements which occur along a fixed or relatively fixed axis where all points in the object move in the same direction to the same extent

Curvilinear Motion

Movements as a result of combined rotation and translation

General Plane Movement

Special type of curvilinear motion where an object or limb is free to rotate around or translate along its own axis

Kinematic Chains

Combination of several joints uniting several segments, important for coordinated movement

Open Kinematic Chain

A chain in which the distal segment ends free in space

Closed Kinematic Chain

A chain in which the distal segments are fixed

Convex-Concave Rule

Rule that improves the fit and stability of a joint and guides the joint's motion

Congruency

Manner in which opposing joint surfaces match with each other during movement

Incongruency

Joint surfaces that do not fit perfectly together

Joint Play

Accessory movement to normal movement that cannot be performed voluntarily

End Feel

Sensation an examiner feels at the end of passive range of motion

Stress

A force or load that the body or its parts resist

Strain

The deformation that occurs in a structure as a result of an externally applied force

Creep

Tissues that undergo elongation with the application of a low level load over time

Lever

A rigid bar that can rotate about a fixed point when a force is applied

1st Class Levers

Levers designed for balance/equilibrium, magnifying the effect of effort

2nd Class Levers

Levers that save force/effort, magnifying the effects of effort with less force required

3rd Class Levers

Levers that produce large motion at the resistance with small motion by the effort

Stable Equilibrium

Effort to disturb an object requires its centre of gravity to be raised

Unstable Equilibrium

Exists when a slight push can destroy it

Neutral Equilibrium

Exists when an object's centre of gravity is neither raised nor lowered when disturbed

Factors Affecting Stability

Size of base of support, height of centre of gravity, line of gravity, mass, friction, segmental alignment, visual factors, physiological factors

Mobility vs. Stability

Great stability makes it difficult to start; great mobility makes it difficult to stop