Kinematics of Human Movement

phases of motion

walking: support/stance, swing

running: support/stance, flight/float, swing

jumping: preparation, takeoff, flight, landing

types of contraction

isometric, concentric, eccentric

isometric

no joint movement upon muscle contraction

concentric

muscle shortening on contraction

eccentric

muscle lengthening on contraction

Quantitative human movements

vector, scalar

Vector

magnitude & direction

scalar

magnitude

Vectors

velocity, acceleration, displacement/position, weight, force & torque, momentum & impulse

scalar

mass, speed, distance, work, power, energy, change rate of speed

coordinate system

local and global system, 2D, 3D system

local system

moving(adapts to the movement); relative angle

Absolute angle

angle of a body segment with reference to the global system

Relative angle

angle of a body segment with reference to the local coordinate system of the proximal segment

global system

non-moving; stays the same; relative angle

Degrees of freedom

type and amount of motion structurally allowed by the anatomical joints in dimension(s); max is 6

Linear & Angular kinematics

position(theta)/displacement(d), velocity(v), angular velocity(omega), acceleration(a), angular acceleration(alpha)

angular velocity

velocity/radius

mechanics

a branch of physics that analyzes the actions of forces on a particle and/or on a mechanical system

bio-mechanics

under kinesiology umbrella; study of structure & function of biological systems by means of the methods of mechanics

kinematics

kinetics

kinesiology

study of human/animal movement, performance, and function by applying the sciences of biomechanics, anatomy, physiology, psychology etc.

kinematics

deals with pure MOTION without reference to masses or forces involved in it

Kinetics

deals with actions of forces in producing or changing the motion of masses

Joint kinematics

osteokinematics, arthrokinematics

types of human movement

translation(linear motion)

rotational(angular motion around a fixed axis)

what is general motion

translation + rotation

osteokinematics

how bone moves in space

describes motion bones relative to sagittal, frontal and transverse planes

ex: flex, ext, abd…

arthrokinematics

how bones are moving relative to each other

describes motions at the articular surfaces

ex. glide/slide; roll; spin

convex-concave rule

Axis of rotation

a straight line about which an object rotates

most joint AOR are through CONVEX joint partner

Roll

multiple contact points between two surfaces

slide/glide

one single point of one surface contact multiple points on another surface

spin

single point of one surface rotate on a single point on another surface

Convex-concave rule

convex surface moving on a fixed concave surface: glides in OPPOSITE direction of roll

concave surface moving on a fixed convex surface: glides in SAME direction of roll

Hinge joint

rotation on plane perpendicular to hinge/axis

moving part perpendicular to hinge/axis

humerus and ulna

Pivot joint

spinning around the axis

moving part parallel to axis

humerus and radius

ellipsoid joint

ellipsoid convex/concave surfaces = spin restricted

bi-planar motion

radius and scaphoid

ball-and-socket joint

spherical convex + concave joint

tri-planar motion

pelvis and femur

plane joint

2 flat joint surfaces

rotation and sliding

metacarpals to carpals

condyloid joint

spherical convex + shallow concave surface(relatively flat)

pretty unstable

knee(has ligaments to stabilize it and restric motion)

mostly bi-planar

saddle joint

convex and concave surface in each joint part = relation between roll and glide depends on the plane of motion

bi-planar rotation

spin restricted

first carpal-metacarpal joint(thumb)

instantaneous axis of rotation

not a fixed rotation

need to use position and time to find the I-AOR each time