biomechanics ch 3

motion can be described in…

qualitative or quantitative terms — complementary tools to analyze movement

qualitative motion analysis

describes how the body “looks” upon visual inspection as it performs skills; subjective

includes position in space, position of body parts and segments of body parts relative to each other.

the two approaches to qualitative analysis

composite approach and component approach

composite approach

AKA total body approach; views whole body as system that progresses through phases as it refines movement pattern

often referred to as developmental biomechanics

breaks down movement patterns into primary body parts however stages of skill progression are based on product of all body parts in combination

component approach

uses same phase method but breaks body down into component sections

sometimes called error analysis strategy

each primary body component is observed and has its own evaluative series of phases that can be advanced independently of each other.

quantitative motion analysis applications

enhance performance of elite athletes, physical therapists (grades of injuries), biomechanical research

two types of quantities in quantitative analysis

scalar and vector quantities

scalar quantity

possesses only magnitude (ex = mass, inertia)

vector quantity

magnitude and precise direction (ex = weight)

all forces are…

vectors

vector direction

way in which force is applied

vector orientation

alignment or inclination of vector in relation to cardinal directions

point of application

the point or location at which the system receives the applied force

magnitude

amount or size of the applied force

line of action

imaginary line extending infinitely along the vector through the tip and tail

vector resolution

process used to resolve single vector into its individual directional component vectors (horizontal and vertical)

component vectors

individual vectors that represent each of the multiple effects that one vector represents

resultant

a vector that represents the sum of all forces acting upon a system

vector composition

combining two or more force vectors into a resultant force vector

vector composition and functional anatomy

muscle groups produce force along multiple lines which converge in one resultant line. (ex = quadriceps, triceps

rotary component

vertical/perpendicular vector component; would cause joint rotation if acting alone

stabilizing/destabilizing component

along x axis; stabilizing if it points toward the join, destabilizing if points away from joint. switches to pointing away from joint when angle is less than 90 degrees.