Biomechanics Flashcards
Biomechanics
- Study of internal and external forces acting on the human body and their effects
- Application of the scientific principles of mechanics to understand movements and actions of human bodies and
sport implements.
- Application of the scientific principles of mechanics to understand movements and actions of human bodies and
- Biomechanics contributes significantly to our knowledge of human movement
- Movement analysis
- Equipment design
- Mechanism of injuries
- Kinesiology and biomechanics are integrally related.
BIOMECHANICS AS AN INTERDISCIPLINE
- Kinesiology
- Natural Sciences
- Mathematics
- Engineering
- Health Sciences
Kinesiology
- Anthropometry
- Physiology
- Psychomotor
- Sports performance
Natural Sciences
- Biophysics
- Physics
- Zoology
Mathematics
- Algebra
- Calculus
- trigonometry
Engineering
- Biomedical
- Electrical
- Mechanical
- Robotics
Health Sciences
- Medicine
- Ergonomics
- Physical therapy
- Prostethics
Why Study Biomechanics?
- To better understand and the various internal and external forces that affect movement and the human body.
- To improve individual’s movements and skill performance.
- To design and conduct programs to enhance movement skills
Areas of Specialization
- Developmental biomechanics
- Clinical biomechanics
- Equipment design
Developmental biomechanics
- Studies movement patterns and how they change
across the lifespan and with people with disabilities.- Example: Cerebral Palsy (CP) research
Clinical biomechanics
- Prevention of injury or diseases that result in movement disorders
- Rehabilitation of people who are injured or have a movement disorder
disease or disability.
Equipment design
- Increases in performance through changes in equipment.
- Example: Wheelchair racers, like this Boston Marathoner, have benefited greatly from improvements in equipment design and research designed to help them streamline and refine their body position to improve performance.
Major Areas of Study in Biomechanics
- Quantitative Biomechanics
- Qualitative Analysis
- Kinematics
- Kinetics
Quantitative Analysis
- Using high-tech instrumentation
- Measuring variables to optimize function or athletic performance
- Foot forces on sprinter’s starting block (Force Platforms)
- Muscle contraction sequence during
running (EMG) - 3-D arm movements of a stroke survivor (Motion capture)
Qualitative Analysis
- Using sight and hearing (also with video recording)
- Use a performance checklist to guide the
observation. - Usually done by coaches and teachers
- Who typically do not have access to complex equipment
- To identify and correct errors:
- “Observe, analyze and correct.”
Kinematics vs. Kinetics
Two ways to describe and analyze human motion:
- Without reference to forces causing motion
- Describing motion in terms of forces that cause it
Kinematics
- Without describing human motion without reference to force causing motion
- Focusing on motion’s spatial and timing characteristics
- Dynamics: Study of mechanical factors that relate to systems in motion.
- Measurements:
- Time
- Displacement
- Velocity
- Acceleration
Kinetics
- Describing motion in terms of forces that cause it
- Internal forces
- Muscles pulling on bones
- Bone-on-bone, inside joints
- External forces acting on the body
- Without contact (e.g., gravity)
- From contact with ground, opponent or equipment
Types of Motion
- Linear Motion
- Angular Motion
- General Motion
Linear Motion
- All body parts move same distance and direction, at the same time
- Translation: linear motion of the whole body
- E.g., Bobsled
Angular Motion
- Body moves on a circular path and rotates about axis of rotation
- Body segments rotate about their joints
- E.g., twisting somersault
General Motion
- Body / segments move linearly and rotate at the same time
- True for most athletic and
everyday activities- E.g., walking
Force
- Force is any action, push or pull, that tends to cause an
object to change is state of motion by experiencing
acceleration- Produced by the actions of muscles.
- The stronger the muscles, the more force the body can produce
- In biomechanics we study the application of internal or
external forces on the body
Absorption of Force
- Common in many physical activities and sports
- The impact of a force should be gradually reduced and spread
- Oer a large surface
- Over time
- Example: drop vertical jump (DVJ)
Force application determines the type of
movement
- Linear motion = force acting on centre of mass/ pivot point
- Angular motion = force not acting on centre of mass/ pivot point and result in torque (moment of force)
Velocity
Speed and direction of a
body.
Acceleration
Change in velocity over time.
Angular Velocity
Angle that is rotated
in a given unit of time.
Angular Acceleration
Change of angular
velocity for a unit of
time
Mechanical Principle: Motion
- Newton’s First Law - Law of Inertia
- Newton’s Second Law - Law of Acceleration
- Newton’s Third Law - Law of Action and Reaction
Newton’s First Law - Law of Inertia
Objects will not change their state of motion unless acted on by an unbalanced external force
Newton’s Second Law - Law of Acceleration
Objects will experience a change in velocity (acceleration)
proportional to the unbalanced external force
Newton’s Third Law - Law of
Action and Reaction
For every action there is an equal and opposite reaction; forces act in pairs that are equal in magnitude and opposite in direction
Lever systems and Motion Mechanics
- Mechanical device performing angular motion
- Components:
- Axis of rotation/fulcrum (aka pivot point)
- Load (or resistance) arm attached to fulcrum
- Force arm attached to fulcrum
- Applied force (muscle in the human body)
- Load (Resistance)
- Human muscles, bones and joint work together as
lever systems
How Levers Work
- Force is applied -> if the turning effect of the force is greater than resistance -> Rotation at the axis / fulcrum occurs
- To determine turning effect, consider the length of force arm and resistance arm
- Levers offer either a mechanical advantage (FA > RA) or a speed advantage (FA < RA)
TYPES OF LEVERS
- Levers perform different functions
- Three basic types of lever exist
- First class
- Second class
- Third class
- Differ based on mechanics and how these components are positioned
- Axis
- Resistance
- Force
FIRST CLASS LEVERS
- Applied force and resistance on opposite side of axis, at un/equal distance from one another
- Example: crowbar
- Human body: head flexion
- Either gives a mechanical or speed advantage depending on where the axis is placed
SECOND CLASS LEVERS
- Applied force and resistance on same side of axis; resistance closer
to axis- Example: wheelbarrow
- Human body - rare: toe raise
- Always gives a mechanical advantage (FA>RA)
THIRD CLASS LEVERS
- Applied force and resistance on same side of axis; force closer to the
axis- Example: fishing
- Human body – many: forearm flexion
- Always gives a speed advantage (FA<RA)
