Kinesiology Concepts and Definitions

I. Introduction

• Kinesiology: The study of human movement through the application of multiple disciplines:

  • Anatomy: The structure of the body.

  • Physiology: The function of body parts.

  • Physics: The principles governing motion and forces.

  • Mechanics: The branch of physics dealing with the behavior of physical bodies when subjected to forces or displacements.

• Significance:

  • Understanding the sources and limitations of human movement is foundational to:

  • The development of physical therapy patient management.

  • Designing therapies that achieve maximum functional outcomes.

II. Biomechanics

• Biomechanics: The application of mechanics to the study of human movement.

• Mechanics: The study of forces exerted on an object.

  • Kinematics: Describes the motion of a body without regard to the forces or torques acting on it.

  • Kinetics: Describes the effect of forces and torques on the body.

III. Arthrokinematic and Osteokinematic Motion

• Arthrokinematic motions: Movements occurring between joint surfaces, which include:

  • Roll: Movement where one joint surface rolls on another.

  • Spine: Similar to rolling but in the context of the spinal movements.

  • Glide or slide: One joint surface sliding over another.

• Osteokinematic motions: Movements of limbs through space about a joint, which can be categorized as:

  • Flexion/extension: Bending and straightening movements.

  • Abduction/adduction: Movement away from and toward the midline.

  • Medial rotation/lateral rotation: Rotation towards and away from the midline.

IV. The Anatomical Position

• The anatomical position is characterized by:

  • An erect posture with weight evenly distributed.

  • Eyes level and facing forward.

  • Feet parallel and slightly apart.

  • Arms at the sides with palms facing forward.

• This position serves as the neutral reference point from which limb segment movements are:

  • Defined

  • Measured

V. Kinetic Chains

• A kinetic chain is defined as a series of connected rigid links, specifically:

  • Limb segments which influence the type of movements performed.

VI. Types of Kinetic Chains

• Closed kinetic chain: The distal segment is fixed, while the proximal segment is free to move.

• Open kinetic chain: The distal segment is free to move with the proximal segment fixed.

VII. Planes of Motion

• Sagittal plane: Passes through the body vertically from anterior to posterior, dividing it into right and left halves.

• Frontal plane: Passes through the body vertically from side to side, dividing it into anterior (front) and posterior (back) halves.

• Horizontal plane: Passes through the body, horizontally dividing it into superior (upper) and inferior (lower) halves.

VIII. Axes of Movement

• Sagittal axis: Passes through joints from anterior to posterior.

• Frontal axis: Passes through joints from side to side.

• Vertical axis: Passes through joints from superior to inferior.

IX. Osteokinematic Motions, Planes, and Axes

• Flexion/extension occur in the sagittal plane about a frontal axis.

• Abduction/adduction occur in the frontal plane about a sagittal axis.

• Medial rotation/lateral rotation takes place in the horizontal plane about a vertical axis.

X. Degrees of Freedom

• Degrees of freedom refer to the number of planes within which a joint can move:

  • Uniaxial (1-degree): Motion in one plane about one axis (e.g., elbow joint).

  • Biaxial (2-degrees): Motion in two planes about two axes (e.g., wrist joint).

• Example joints:

  • Shoulder and hip joints exhibit three degrees of freedom due to their complex motion capabilities.

  • Elbow, a uniaxial joint, has one degree of freedom.

XI. Range of Motion

• Range of Motion (ROM): The amount of motion a joint can exhibit in any of its possible directional movements.

• Measured using a goniometer, which quantifies the angle of movement.

• The anatomical position is considered the zero point for measurement of joint angles.