Ch. 1 & 2 Functional Kinesiology & Biomechanics

Kinesiology

- study of (human) movement

- has interaction with anatomy, biomechanics, and physiology

Kinematics

- motion of a body without regard to the forces or torques that produce the motion (how the body moves and what that looks like)

- we take out the drivers of the motion (muscles) and simply look at how the body moves

- can look at the whole body or a segment

Two Types of Motion

- translation

- rotation

- these relate to kinematics

Translation

- straight line: linear motion, part(s) move parallel to every other part of the body (movement that occurs in a straight line)

- curvilinear: not all translation is in a straight line (walking we track how the COG moves)

Rotation

- the rigid body moves in a circular path about a 'pivot' (looking at movement about a joint, a pivot point or axis of rotation)

- pivot = axis of rotation

- rotational motion occurs around axis

- no rotational motion occurs at axis

- movement is either active or passive

Active Movement

- muscular contraction

- movement is generated through a muscle contraction (eccentric, concentric, etc.)

Passive Movement

- other than muscle

- something else causes the movement (gravity, you got pushed, the person themselves don't cause the movement)

Osteokinematics

- motion of bones relative to 3 cardinal planes

- sagittal, frontal (coronal), and transverse (horizontal)

- bones rotate about a joint in a plane that is perpendicular to an axis of rotation (pivot point runs perpendicular to the plane of motion you're looking at)

Sagittal Plane

- right and left halves

- flexion/extension and dorsi/plantar flexion

- axis is anterior/posterior

- movement path is forward or backward, close to the midline (lunge, bicep curls, bench press)

Frontal (Coronal) Plane

- anterior and posterior portions

- abduction/adduction and ulnar/radial deviation

- axis is medial/lateral

- side to side movements (side lunge, lateral raises, jumping jacks, shuffling)

Transverse (Horizontal) Plane

- superior and inferior portions

- medial (internal) and lateral (external) rotation

- axis is superior/inferior

- movement path is a twisting motion around the body's midline, trunk rotation (trunk twists, russian twists, swinging a bat, throwing a ball

Degrees of Freedom

- number of movements allowed at a joint

- maximum of 3 degrees of angular freedom

1. flexion/extension

2. abduction/adduction

3. medial/lateral rotation

- this relates to kinematics

Open Kinetic Chain

- distal segment is not fixed, the proximal segment is fixed (kicking a ball)

Closed Kinetic Chain

- the distal segment is fixed, the proximal segment is not fixed

- ex: with a squat the foot is fixed on the ground, but there is still flex/ext through the knee

Arthrokinematics

- motion that occurs between articulating surfaces

- 3 different types (roll, slide, spin)

- we're looking at how the convex looks with the concave

- arthrokinemtics and osteokinematics happen together

Roll

- a type of arthokinematics

- multiple/multiple

- multiple points roll across multiple points (imagine the ball)

Slide

- a type of arthokinematics

- single/multiple

- one point is fixed, but it slides across multiple points

Spin

- a type of arthokinematics

- single/single

- one point sits on another and spins on one single point

Concave on Convex

- roll and slide occur in the same direction

Convex on Concave

- roll and slide happen in opposite directions (roll happens in 1 direction and slide happens in another direction)

Close Packed Positions (CPP) at a Joint

- articular surfaces have maximal congruency

- capsules and ligament are taut

- has the least amount of accessory movement

- usually near the end ROM

- joint surfaces are tightly packed together, they line up nicely, structures are tight, not much motion

Loose Packed Positions (LPP) at a Joint

- all other positions from CPP

- greatest amount of accessory movement

- usually greatest near mid-range ROM

- little more give to the joint, you can test integrity better (test a ligament by putting them in an LPP)

Kinetics

- describes the effects of forces on the body

- forces either move or stabilize a body, though if excessive it can cause injury

- several different types of forces (tension, compression, bending, shearing, torsion)

Tension

- a force on the body

- stretches something

Compression

- a force on the body

- pushes things down into each other (squish together)

Bending

- a force on the body

- like bending/breaking a pencil

Shearing

- a force on the body

- shear stress -> combination of compression and bending

Torsion

- a force on the body

- twisting (like ringing out a washcloth)

Stress-Strain Curve

- shows the ability of a tissue to withstand forces

- shows how a biological tissue reacts to be stretched (tendon)

- strain: increase in length which results in stress

- stress: a way of describing force

Stress-Strain Curve Zones

- elastic zone: tissue is very tight and maintains shape

- plastic zone: some sustained changes to the tissue, once tissue goes plastic it never regains its normal length, we then stretch it so far we get micro failure and it eventually ruptures

- calculate relationship between stress and strain to get stiffness

Viscoelastic

- tissues that exhibit changes with time are considered viscoelastic

- viscoelastic means they have different characteristics

- characteristics of viscoelasticity: creep and rate of loading

Creep

- characteristic of viscoelasticity

- you apply a load to a structure and you maintain that load

- the length/orientation will change

- think of how the apple tree changes

Rate of Loading

- characteristic of viscoelasticity

- the faster the tissue is loaded, the faster it responds

- as the rate of loading increase, the stiffness of the tissue also increases

Viscoelastic Tissue

- tissues that have both elastic and viscous properties -> they influence amount and rate of passive tension

- viscosity and elasticity serve as damping mechanisms

Elasticity

- property of viscoelastic tissue

- muscle is able to store part of the energy used to create stretched state (can be useful in preventing injury)

- elasticity helps so tissue doesn't break each time we load it

Viscosity

- property of viscoelastic tissue

- rate dependent resistance encountered between 2 surfaces of fluid-like tissue

- slow loading gives the tissue time to adapt, fast loading means it changes fast

- there's rate dependency and a protective mechanism

Rate Dependency

- characteristic of viscosity

- internal resistance of muscle to elongation increases with rate of stretch

Protective Mechanism

- characteristic of viscosity

- prolongs the application of force to allow for gradual elongation

Internal and External Forces

- with kinetics, forces may be internal or external

- internal: "within the body", force from our muscles, muscles are torque producers

- external: "outside the body", gravity, imposed load, friction, we then have to do something in response to this

- forces may create translation (goes down) or rotation (axis of rotation)

Muscle Contraction Types

- muscle produces force via 3 types of contractions

- isometric: muscle stays the same length, but there is a contraction

- concentric: the muscle gets shorter with a contraction (flexion)

- eccentric: muscle gets longer with a contraction (extension)

Determining a Muscle's Action

- number of degrees of freedom

- identify the 'line of pull'

- determine the location of the 'line of pull' with respect to the 'axis of rotation'

- muscular actions may change with alternations in joint angle

Muscle and Joint Interaction

- where muscles fall in relation to the joint for orientation and to understand the axis of rotation

Muscular Action Terminology

- agonist: muscles are the prime movers and drivers

- antagonist: not the driver (like flexing the elbow, the triceps does work, but not the major driver of that action)

- synergists: synergy, muscles work together (multiple muscles flex the elbow

- force couple: muscles pulling in different directions causing rotation

Levers

- lever = rod suspended across a pivot or axis

- levers convert force into torque

- 'leverage' = relative moment arm length

- internal and external forces create torques via levers within the body

- 3 types of lever systems

First Class Lever

- the fulcrum/axis of rotation sits in the center (see-saw)

- axis of rotation between opposing forces

- IMA may or may not be > than EMA (> or

Second Class Lever

- axis of rotation is located at the end

- there's very few of these, operates like a wheelbarrow (like a calf raise)

- IMA > EMA (>1)

Third Class Lever

- axis of rotation located at the end

- we have a lot of these, most joints are these, slightly inefficient

- very small IMA, has a very long lever (holding a weight has a long lever, it's far from the axis of rotation)

- IMA < EMA (

Joints

- joint = junction or pivot point between bones

- joint functions: allows movement of the body, transfer/dissipate forces

- integrity of a joint will influence its quality of movement

- movement occurs at the joint, some joints don't move

Classification of Joints

- based on anatomic structure

- synarthroses

- diarthrosis

Synarthroses - Fibrous

- these joints tend to be really stable

- bones are held together by dense irregular CT

- rigid junction

- e.g. sutures of the skull; distal tib-fib joint

Synarthroses - Cartilaginous

- these have little more movement than synarthroses-fibrous

- bones held together by fibrocartilage

- restrained movements

- e.g. inter body joint of spine; pubic symphysis

Diarthorsis - Synovial Joint

- these joints tend to have the same parts

- synovial fluid, articular cartilage, capsule, synovial membrane, ligaments, blood vessels, sensory nerves

- e.g. intra-articular discs, labrum, fat pads, plicae

Synovial Joints

- these are based on mechanical analogy

Hinge Joint

- flexion/extension only

- elbow joint

Pivot Joint

- spin, radius spins, rotating around a fixed point

- bend elbow 90° and flip hands

Ellipsoid Joint

- restricted spin (flattened ball)

- 2 degree of freedom

- the wrist

- flexion/extension and radial/ulnar deviation

Ball and Socket Joint

- the hip and shoulder

Plane Joint

- sliding and gliding

- intercarpal bones (wrist)

Saddle Joint

- saddle has both concave and convex aspects to it, depends on which way you look at it

- sternoclavicular joint

Condyloid Joint

- flattened socket

- 2 degrees of freedom

- the knee

- the condyles of the femur are convex sitting on concave

Simplifying Classification

- 2 types

- ovoid: 1 partner is concave, the other is convex

- saddle: each partner has concave and convex characteristics to it

Connective Tissue Materials

- these are biological materials that form connective tissue within joints

- fibers (collagen, elastin)

- ground substance (glycosaminoglycans, water, solutes, this all fills stuff in)

- cells (osteoblasts break stuff down, osteoclasts build it up

- the proportion and arrangement of all this influences mechanical properties

Connective Tissue in Joint Structures

- these form the structure of joints

- dense CT

- articular cartilage

- fibrocartilage

- bone

Dense Connective Tissue

- capsule, fascia, ligaments/tendons

- high proportion of type 1 collagen

- orientation assists with resisting multiplanar forces

Articular Cartilage

- covers the ends of articulating bones in synovial joints

- 1-7mm thick, low coefficient of friction

- avascular and aneural

- high proportion of type 2 collagen and ground substance

- articular cartilage wears down causing OA

Fibrocartilage

- has properties of both dense irregular CT and articular cartilage

- ideal schock absorber

- labrum, menisci, intervertebral discs

- aneural, peripheral blood supply (the extent to which a structure has blood supply determines how it heals)

Bone

- provides levers and rigid support

- cancellous (spongy) bone, and compact (cortical) bone

- constant remodeling

- greatest strength when loaded via long axis

Connective Tissue Facts

- there's only so much load the tissues and bones can take before it breaks

- specific adaptations to imposed demands (SAID): the body can adapt to loads

- structures react differently depending on their make-up

- ligaments typically get stretched and if it goes too far it can rupture

- ground substance: how much give does it have

Effects of Aging

- process is highly individual, depends on type and frequency of activity, and medical and nutritional factors

- generally there's a decrease in rate of fiber and GAG replacement

- GAGs are smaller and less numerous (decreased hydration, decreased compressive strength, increase in adhesions)

- the key to slowing this all down is eating right and working out (by having a higher activity level, you have a better chance at preserving the quality of tissues)

Immobilization, Trauma, and Arthritis

- immobilization leads to decreased strength and quality of CT, loss occurs quicker than during recovery (use it or lose it)

- trauma can be acute or chronic which heal differently

- arthritis changes how quick we move and overall how we move (OA and RA)

Summary

- three different broad classifications of joints

- synovial joints provide varying amounts of motion and stability

- motions are complex and are influenced by the geometry

- injury can either be acute or chronic

- recovery is influenced by many factors including age, general health, blood supply, etc