Fundamentals of Biomechanics
‫مبادئ الميكانيكا الحيوية‬
Lecture #1
By Dr. Ahmed Darwish
Outline of this lecture
• Define the terms biomechanics, statics, dynamics, kinematics, and
kinetics, and explain the ways in which they are related.
• Describe the scope of scientific inquiry addressed by biomechanists.
• Distinguish between qualitative and quantitative approaches for
analyzing human movement.
• Explain how to formulate questions for qualitative analysis of human
movement.
BIOMECHANICS: DEFINITION AND
PERSPECTIVE
• The term biomechanics combines the prefix bio,
meaning “life,” with the field of mechanics, which is
the study of the actions of forces.
Kinesiology: study of the description
of
motion, including considerations of
space and time
mechanics: branch of physics that
analyzes the actions of forces on
particles
and
mechanical
systems
statics:
branch of
mechanics dealing
with systems in a constant state of
motion
dynamics: branch of mechanics
dealing
with systems subject to acceleration
kinematics: study of the description of
motion, including considerations of
space and time
kinetics: study of the action of forces
What Problems Are Studied by
Biomechanists?
• Locomotion patterns of animals.
• Running (running economy)
• Effect of microgravity on human anatomy and physiology (space).
• Prosthetics
• Occupational biomechanics
Reading Assignment
Page 8 & 9- Tools that
Enhance Human
Biomechanical Function
Professions that Rely on Knowledge of
Biomechanics
• Physical education teachers, coaches, and personal trainers need
knowledge of the biomechanical basis of exercise and sport skill techniques
to properly instruct students, athletes, and clients.
• Sport analysts hired by professional sport teams utilize biomechanics in
diagnosing and correcting technique errors (especially for pitching and
batting in baseball).
• Golf coaches use knowledge of biomechanical aspects of the golf swing to
diagnose errors and offer advice to both professional and amateur golfers.
• Athletic trainers, physical therapists, and chiropractors rely on knowledge
of biomechanics to safely and effectively rehabilitate injuries.
• Mechanical engineers and biomechanists utilize knowledge of
biomechanics in designing sport shoes, clothing, and equipment.
Why Study Biomechanics?
• The knowledgeable human movement analyst should be able to answer the
following types of questions related to biomechanics:
• Why is swimming not the best form of exercise for individuals with osteoporosis?
• What is the biomechanical principle behind variable resistance exercise
machines?
• What is the safest way to lift a heavy object?
• Is it possible to judge what movements are more/ less economical from visual
observation?
• At what angle should a ball, discus, hammer, or javelin be thrown for maximum
distance?
• From what distance and angle is it best to observe a patient walk down a ramp or
a volleyball player execute a serve?
• What strategies can an elderly person or a football lineman employ to maximize
stability?
PROBLEM-SOLVING APPROACH
Solving Qualitative Problems
• To effectively analyze a movement, it is essential first to formulate one or
more questions regarding the movement. Depending on the specific
purpose of the analysis, the questions to be framed may be general or
specific. General questions, for example, might include the following:
• 1. Is the movement being performed with adequate (or optimal) force?
• 2. Is the movement being performed through an appropriate range of
motion?
• 3. Is the sequencing of body movements appropriate (or optimal) for
execution of the skill?
• 4. Why does this elderly woman have a tendency to fall?
• 5. Why is this shot putter not getting more distance?
Kinematic Concepts for
Analyzing Human Motion
FORMS OF MOTION
• Linear Motion: along a line that may be straight or curved,
with all parts of the body moving in the same direction at
the same speed
• rectilinear: along a straight line
• curvilinear: along a curved line
• Angular Motion: involving rotation around a central line or
point
• General Motion: motion involving translation and rotation
simultaneously
• Mechanical Systems : object or group of objects chosen by
the analyst for study
STANDARD REFERENCE TERMINOLOGY
• Anatomical Reference Position: erect standing position with all
body parts, including the palms of the hands, facing forward;
considered the starting position for body segment movements
• Directional terms:
• Superior: closer to the head (In zoology, the synonymous term is cranial.)
• Inferior: farther away from the head (In zoology, the synonymous term is caudal.)
• Anterior: toward the front of the body (In zoology, the synonymous term is ventral.)
• Posterior: toward the back of the body (In zoology, the synonymous term is dorsal.)
• Medial: toward the midline of the body
• Lateral: away from the midline of the body
• Proximal: closer in proximity to the trunk (For example, the knee is proximal to the
ankle.)
• Distal: at a distance from the trunk (For example, the wrist is distal to the elbow.)
• Superficial: toward the surface of the body
• Deep: inside the body and away from the body surface
Anatomical Reference Planes/Axes
JOINT MOVEMENT TERMINOLOGY
• When the human body is in anatomical reference position, all body segments
are considered to be positioned at zero degrees. Rotation of a body segment
away from anatomical position is named according to the direction of motion
and is measured as the angle between the body segment’s position and
anatomical position.
• Sagittal Plane Movements:
• From anatomical position, the three primary movements occurring in the sagittal plane are flexion,
extension, and hyperextension.
• Flexion includes anteriorly directed sagittal plane rotations of the head, trunk, upper arm, forearm, hand,
and hip, and posteriorly directed sagittal plane rotation of the lower leg.
• Extension is defined as the movement that returns a body segment to anatomical position from a
position of flexion.
• Hyperextension is the rotation beyond anatomical position in the direction opposite the direction of
flexion.
Frontal Plane Movements
• The major frontal plane rotational movements are abduction and adduction.
• Abduction (abduct meaning “to take away”) moves a body segment away from the midline of the
body; adduction (add meaning “to bring back”) moves a body segment closer to the midline of the
body