KIN 222: Biomechanics

Biomechanics

application of the mechanical principles to the study of biological systems

Kinesiology

the study of human movement

Bio

the study of biological systems; includes the things that take on the traits of human movement like robotics or prosthetics

Mechanics

the underlying principles of what it causing movement, why it is occurring that way, and how we can alter and change these movements

2 Primary Aims of Biomechanics

to improve performance and reduce the risk of injury; can do this by modifying techniques and equipment with the help of knowledge in the biomechanics of movement

Reducing Risk of Injury

you can never eliminate all injuries, but you can decrease the potential for injury; this is important for all athletes as injury and performance heavily affect one another

Mechanopathology

the mechanics that result in injury; help to cause injury

Pathomechanics

the mechanics that are the result of an injury; usually asymmetrical alterations that are detrimental to the overall health of a body

like a limp that is a side effect of having an injury already in place

Performance

not limited to high-achieving athletic competitions; it occurs during any human activity like getting off of a couch

the goals is to increase the efficiency of movement in areas of normal tasks, as well as sports

2 Major Branches of Biomechanics of Interest

• statics

• dynamics

Statics

systems in equilibrium; no acceleration = no change in movement

systems in equilibrium can be moving but have not additional forces that cause a change in movement

Dynamics

systems undergoing acceleration; newton’s laws of motion

Kinematics

“motion”; the study of motion without consideration of the cause

“how is it moving?” “what is an object’s position in time and space?”

includes position, velocity, and acceleration

Kinetics

“force”; study of the causes of motion

“why is the object moving?”

includes force, torque or moment

Types of Biomechanics

• sports biomechanics; improve athletic performance and risk of injury

• ergonomics; using some material, product, or system to improve performance and reduce injury risk

• clinical biomechanics; utilized in a patient population to improve basic human movement to restore normal function

• materials testing; sport product testing, app building, motion capture technology

Analyzing Movement

• top-down approach; from the whole body to tissue level (how segments play off of one another)

  • used the most often

• bottom-up approach; from tissue level to whole body

  • used to study pathomechanics; important to consider the whole body during examination of an injury

Classes of Movement

• discrete

• serial

• cyclic

Discrete Movement

distinct beginning and end without the movement repeating

like a maximum vertical jump; start and end in the same position

Serial Movement

distinct beginning and end, but links at least 2 discrete movements; different components in the middle

like a triple jump

Cyclic Movement

involves repeating a pattern over and over again; no discrete beginning or end

like running; right then left foot over and over again

Phases of Movement

• preparation

• propulsive or acceleration

• braking

allows for easier analysis of what is actually happening during a movement; the muscle and joint actions

the more complex the movement, the more phases will be needed to analyze

Preparation Phase

puts body in advantageous position to maximize displacement

Propulsive or Acceleration Phase

generate energy and deliver segments; body segments working together to complete the movement

Braking

energy absorbed from external object or environment; stop movement and bring the body to a full stop in a safe manner

Typical Biomechanics Labs Include…

• 3D motion capture systems

• force platforms

• electromyography

3D Motion Capture Systems

reflective markers are places on specific bony markers on an individual, and these markers moved through time and space

6-20 cameras track the markers and create a 3D model of the motion captured

Force Platforms or Plates

measures forces generated by a body standing or moving across them

can measure any force in contact with plate; anterior/posterior, medial/lateral, etc.

Electromyography

evaluation and recording of electrical activity of skeletal muscle

• surface: electrodes are places on skin to measure the electrical activity of muscles underneath the skin

• indwelling: needles that go directly into the muscle; can make it harder to perform intense dynamic movements

Anatomical Neutral Position

reference point for all terms in kinesiology, anatomy, and biomechanics

assumes the starting neutral position; palms facing forward, gaze straight ahead

Why is Anatomical Neutral Position Important?

when dealing with the human body and movement, professionals with clients need to be on the same page with terminology

written notes get transferred to other professionals or personnel that work with the athlete

Planes of Motion

• sagittal

• frontal

• transverse

each of these has an associated acid of rotation that is perpendicular to it

Axis of Rotation

when a joint moves, it rotates about an axis that is perpendicular to its respective plane

Mediolateral Axis

associated with the sagittal plane; responsible for flexion and extension

goes through the ankle, knee, and hip joint; viewed from the side and runs from left to right across the body

Anteroposterior Axis

associated with the frontal plane; responsible for abduction and adduction

goes through the hip joint centre to allow adduction and abduction of the hip; viewed from the front or back

Longitudinal Axis

associated with the transverse plane; responsible for internal and external rotation

goes through the shoulder joint centre to allow for internal or external rotation; axis is vertical straight up and down

Directional Anatomical Terminology

important to explain human movement or directional changes or locations within movement patterns; always in reference to a person in anatomical neutral position

Proximal

a body part closer to the midline or trunk in reference to a structure

in regards to the hips, the thigh is more ____ than the shin

Distal

a body part is further away from the midline or trunk in reference to a structure

regarding the hips, the foot is more ____ than the shin

Superior

a body part that is higher in the vertical direction; in reference to a global reference frame

the head is ____ to the upper arm

Inferior

a body part lower in the vertical direction; in reference to a global reference frame

the foot is ____ to the knee

Medial

a body part closer to the midline

the nose is ___ to the ears

Lateral

a body part is further away from the midline

the thumb is ____ to the pinky finger

Supine

refers to someone laying flat on their back

Prone

refers to someone laying flat on their stomach

Anterior

refers to the front of the body

the knee cap is on the ____ portion of the body

Posterior

refers to the back of the body

the heel of the foot is on the ____ portion of the body

Unilateral

refers to only one side of the body

a person performing a _____ bicep curl would only move one arm at a time

Bilateral

refers to two sides of the body

a person performing ____ bicep curls would move both arms at the same time

Ipsilateral

refers to the same side

Contralateral

refers to a body part being on the opposite side

a person stepped to throw a ball with the leg _____ to their throwing arm

Kinematics

describes the motion of objects or rigid bodies

3 Measures of Kinematics

• displacement

• velocity

• acceleration

Displacement

change in linear or angular position of an object or rigid body

Velocity

rate of change in displacement (linear or angular) of an object or rigid body

Acceleration

rate of change in velocity (linear or angular) of an object or rigid body

Linear Kinematics

motion that occurs in a straight line from one location to another

all body parts move the same distance in the same direction at the same time

two types: rectilinear and curvilinear

Rectilinear Kinematics

linear motion that occurs in a straight line

Curvilinear Kinematics

linear motion that occurs in a curved path

all parts of the object one in the same direction, the same distance, and at the same time; no axis of rotation but takes a curved trajectory as it moves along a curved path

Angular Kinematics

movement of an object or rigid body around a fixed point; rotation around an axis

all parts of the object or rigid body moved through the same angle, in the same direction and at the same time

all parts of the object or rigid body do not move the same distance; like the elbow during a pitch does not move that same range of distance as the wrist that is farther from the axis or shoulder

Internal Axis

within the body at the joint centre; joint rotates around the joint axis in a angular fashion

like during a squat

External Axis

outside the body; object moves around the fixed axis

like a gymnast rotating about a bar

Mathematical Quantities

• scalar

• vector

Scalar

has only a magnitude

like time, speed, distance, and work

Vector

has a magnitude and a direction

like displacement, velocity, acceleration, and force

Systems in the Human Body that Work Together to Create Movement

• skeletal system

• muscular system

• nervous system

create a complex system of interconnected links that integrate various systems of the body to conduct motion

Skeletal System

composed of all the bones within the human body

Muscular System

composed of all the muscles in the human body that assist with motion; the primary muscle focus is skeletal or voluntary muscle

Nervous System

composed of all nerve tissues that assist with transmitting electrical signals or impulses throughout the body

Articulations

the intersection of bones

is extremely important to understand movement because the motion observes occurs at the joint not within the segments themselves; movement occurs around a joint

the muscles that cross joints result in movement or angular motion

Linear Motion Can Be Analyzed Through…

an examination of the motion of the centre of gravity or the path of a projected object

Angular Motion Can Take Place…

around an axis running through a joint, through the centre of gravity, or about an external axis

The 7 General Movements

• flexion

• extension

• abduction

• adduction

• internal rotation

• external rotation

• circumduction

Flexion

the bending movement that brings two segments together

like lifting the elbow from a anatomical neural position; bicep curl

Extension

the straightening movement that separates segments farther from one another

like lowering the elbow from a flexed position

Hyperflexion

if flexion movement goes beyond the normal range of flexion

like when the arm moves moves forward and up into flexion and past the head towards the back, beyond 180 degrees

Hyperextension

if the extension movement goes beyond the normal range of extension

like when the arm moves in the sagittal plane posteriorly past the neutral position

Abduction

segments moving away from the midline

like when the arm is lifted from anatomical neutral to the side

Adduction

segments moving closer towards the midline

like when the arm is brought back to anatomical neutral from being raised to the side

Internal Rotation

the anterior surface of a segment rotating internally or medially

like the femur rotating internally from an anatomical neutral

External Rotation

the anterior surface of a segment rotating externally or laterally

like the femur rotating externally from the anatomical neutral position

Circumduction

the combination of movements including adduction, abduction, flexion, and extension

commonly observes as the windmill motion that can occur at the shoulder

like the circular motion that can be observed at the shoulder

Elevation

the superior movement of the scapula; like shrugging the shoulders

Depression

inferior movement of the scapula; moving the scapula downward

can only be performed if that scapula has some degree of elevation

Protraction

the abducted movement of the scapula; like reaching for something in front of you or giving yourself a hug

Retraction

the adducted movement of the scapula; like squeezing your scapula together

Upward Rotation of the Shoulder Girdle

the upward movement of the scapula

Downward Rotation of the Shoulder Girdle

the downward movement of the scapula

Anterior Tilt of the Shoulder Girdle

the anterior movement of the scapula; tilting forward

Posterior Tilt of the Shoulder Girdle

the posterior movement of the scapula; tilting backwards

Flexion of the Shoulder Joint

the superior movements of the humerus

Extension of the Shoulder Joint

the inferior movement of the humerus

Hyperextension of the Shoulder Joint

the excessive posterior movement of the humerus upon reaching full extension

Shoulder Joint

“glenohumeral articulation”; consists of the glenoid fossa where the head of the humerus sits within

a ball and socket joint; allows for a large ROM but little stability

Internal Rotation of the Shoulder Joint

the medial movement of the humerus

External Rotation of the Shoulder Joint

the lateral movement of the humerus

Abduction of the Shoulder Joint

movement of the humerus away from the midline

Adduction of the Shoulder Joint

the movement of the humerus closer to the midline

Diagonal Abduction of the Shoulder Joint

the humerus moving away from the midline in a diagonal manner

Diagonal Adduction of the Shoulder Joint

the humerus moving closer to the midline in a diagonal manner

Horizontal Abduction of the Shoulder Joint

the humerus moving away from the midline in a horizontal manner