KIN 150 exam 3

linear motion

motion along a straight line produced by a force acting directly through an objects (persons) center of mass

when does rotation happen

when force is applied outside of the center of mass (above or below)

what is angular (rotational) motion

motion about a fixed point or a point axis, can have linear motion as well

what is the difference between rotation and swing

both are angular motion, both are created with off center forces around and axis. A swing rotates about an external axis (on a bar) , rotation is an internal axis (somersault)

rotation

turning about the body’ internal axis. It can be transverse, longitudinal, or anterior/posterior axis

swinging

rotation about an external axis. Can be on bars, rings, pommel horse. Can occur anywhere that there is an external axis to rotate around. uses force and lever arm to create torque. off center force multiplied by length of arm, gives torque.

the greater the force we can generate, the greater the distance from our axis we have applied

** axis is not in center of mass

where does a swing start from

swings can start from either a hang or a support, therefore we can do them before swings

swings are helpful in developing motor and physical components of fitness, how?

momentum and finesse, ability to find the rhythm

it is not about power, or balance

how to generate swing

internal force- for both hang and support, utilize muscles of core and upper body

External forces- gravity and action/reaction of the bar

gravity is the off center force being applied

mechanics of swinging

descending phase and ascending

descending phase

gravity- positive off center force= increased rotation about external axis

to maximize- increase distance between center of mass and axis of rotation, lengthen your body as much as possible

ascending phase

gravity- negative off center force= decreased rotation about external axis

teaching swings

need to maximize gravity but also use internal torques as well

when you back swing, want to hallow so you can arch at the bottom and kick into another hallow/pike position on the ascending swing, bent at the waist, rather then the shoulders

how to initiate a swing

need an off center torque

COM must move off center for gravity to be applied, mut be done quickly

core development and upper body strength are helpful as well as flexibiltiy of the trunk and shoulder

how to maximize swing

GRF (action reaction)- internal muscular contraction, more force= more swing

utilize muscles of core and upper body

use the bar

coordinate the relaxation with the contraction phases (use visual, kinesthtic cues for timing)

decreases negative effect of gravity/ increases positive effect

decrease negative effect of friction

how to swing safely

1. hook, not squeeze

2. swing low to start

3. release are at the top of backward swing

4. regrasp the bar at the top of backwards swings (dead psot)

5. minimal inverted swings, and when ready. Do not regrasp while inverted

6. set up apparatus appropriately

7. use chalk to allow swing

8. Thumbs around skinny bar

axes that we rotate on

transverse. longitudinal and A/P

what axis do we swing about

an external axis on the bar

what is learning

relatively permanent acquisition of skill developed with repetition or a relatively permanent change in action/behavior

what is repetition

10000 hours of things to become efficent in a skill (be able to do it from muscle memory)

senses role in learning

(visual, tactile, auditory, kinesthetic)

out brain goes through a process when attempting new motor skills. it takes on info from our senses to identify what is happening with this motor skill. either recognizes it as already learned, then pulling up the motor pattern to complete skill

long term skills

motor patterns for skills done for a long time develop extremely strong neural networks so they require less brain space, making it easier to do other things will preforming the skill (multitasking) The pathway becomes reinforced so it i the dominant way the body preforms the skill or responds to stimuli

once a bad habit id formed and the pathways are reinforced it is hard to break

visual

they need to see what they are to do, demonstrate, use props, show them where to put there hands, etc

Auditory

they like to hear what the instructions are, they respond well to verbal instructions, rhymes, word play

kinesthetic

they need to feel what it is like to do the skill. touch the body part you want them to move. many times spotting them through the skill is the kinesthetic cue. Both proprioceptive and vestibular

tactile

similar to kinesthetic but instead of gross motor movements, fine motor skills, hand eye coordination, have something to feel (felt, foam)

how you can apply the learning styles to a cartwheel

visual- look at your hands on the floor, put hands on the target (use props)

auditory- say 1-2-3-4 (hand, hand, foot, foot)

Kinesthetic- touch their cartwheel foot to put them in front ot spot them through it

tactile- have felt o floor to place hands, use chalk on hands to draw on floor

what are the three stages of learning

cognitive, intermediate, automatic

cognitive

understand, organize, thoughts into a process, get the idea/feel, identify and select the properties mot relavant, trial and error, do not over teach or over verbalize

intermediate (associative phase)

Learning is noticeable, motor change occurring

Errors eliminated

Movement patterns are predictable and stable (consistent)

Models are important

Verbalize with key words

automatic (expert)

Movement becomes reflexive

Performance is consistent and automatic

Looks easy

Fine tuning stage

attention can be focused on other cues

movements can be done within a variety of situations

factors that facilitate learning skills

•ESP&F and motor ABC’S are well developed

•Short practice bouts repeated often is more effective than lengthy time

•Material interesting and meaningful

•Learning is fastest when strongly motivated

•Progress more rapid when success is achieved more often

•Motor performance is enhanced in social context

•Feedback is important

•“Part” practice in early learning, and then move to “whole” practice

what is the teaching process

teacher led —> drills and progressions —> reciprical (partner) teaching —> guided discovery —> problem solving —> learner led

direct (traditional)

the coach names, explains, and demonstrates

problem solving

the coach asks “ show me different body shapes when you jump”

guided/indirect

s skipping rope is elevated until the gymnasts are doing a tuck jump

Drills vs movement problems

specific drills form teacher vs giving the students movement problems to solve on their own

efficiency vs creativity

advantages and disadvantages to each

drills and progressions = proper technique

problem solving = creativity and individual differences

some combination of both is likley best, but every individual and teacher are different

Spotting

a coach should not remedy a potentially dangerous situation by spotting

remove dangerous situations

spotting one gymnast means you aren’t spotting others

make enviroment safe

what is linear motion

repetitive displacement of the center of mass. (not staying in the same spot) BOM is repetitively moving

can be forward backwards up or down

how is linear motion created

• Internal and external forces cause CofM shift

• Causing instability, reestablished ability

• Repetitive nature= repetitive forces

• VGRF- vertical ground reaction force on a force plate

what is rotation

• Skills when the body moves about one of its three internal axes 

1. Longitudinal- turns, twists, pirouettes

2. Transverse axis- saltos, rolls, bar circles

3. anterior/posterior axis- cartwheels, side roll

the mechanics of rotation

Generated by a single or pair of ‘off centre’ forces

Generated by ground reaction force (newton's third law)

Any force passing through the centre of mass will only generate linear motion (displacement)

“off center” forces

• The further ‘off center’ the force, the greater the rotation and the less the linear displacement

force couple

• Two off center forces acting simultaneously to create rotation

• Forces are acting in different directions, creating rotation in one direction

• To get more rotation, add more force

how to maximize rotation

1. Increase the force- contact (external) and non-contact (internal)

2. Increase the distance the force is applied away from the axis (torque)

3. Apply the force for as long as optimally possible. contact time= push for longer

Impulse = force x time

altering rotation

based on distribution of mass around rotational axis

• Mass closer to axis, increases rotational velocity

• Mass further from axis, decreases rotational velocity

springs

skills from abase of support in a single explosive movement

can be initiated from either legs, arms, or both or body on a trampoline

can be from muscles or an apparatus to help

spring mechanics

it is a rapid (explosive) displacement of the centre of mass

displacement id the moving of something from its place or position

can be in the vertical or horizontal

typically associated with the physical component of power

what is power

how fast one can generate maximal force

combination of both speed and strength

biomechanical concept of power

power= force x velocity

essential it states that the faster we displace something (velocity) the greater the power generated

displacement

if you want to displace something faster, either increase force or decrease the time

at a certain point too much velocity will decrease force

use of non-support limbs

use of newtons third law

“every action has an equal, opposite and concurrent reaction”

uses both strength and speed

developing power

must develop adequate levels of strength and endurance before adding speed

this reduces the potential for injury because of the high levels of strain placed muscles, tendons, and ligaments

few reps (1-6) max 10 but as quickly as possible

ex) plyometrics, olympic lifts

rigid body for producing powerful spring

guarantees that the generated force is utilized fully rather then being absorbed by the body and joints

the goal is to not have the forces absorbed into the body but to use ot in aiding displacement

Labans Movement Analysis

by Rudolf Laban (1879- 1958)

to bring movement variety into a known set of parameters

to allow instructor endless creativity

for challenge

sports have prescribed technical movements, where activity is not any restrictions

physical literacy is the motivation confidence, physical competence knowledge and understanding to value and take responsibility for engagement in physical activities for life

able to apply to dance/gymnastics/games/fitness

General human movement: concepts

get away from thinking of gymnastics as a ‘sport” rather think of it in terms of the movement underlying gymnastics activities

kinesphere

used to define “ the sphere around the body whose periphery can be reached by easily extended limbs without steeping away from that place which is the point of support when standing on one foot”

when the body moves, the kinesphere also moves

how to analyze movement

ask four key questions

• what moves

• where does it move

• how does it move

• with whom or what does it move

Movement variable #1 body

parts- contact: body part integral to the skill land, support/balance/hang, swing, spring, locomote from different body parts

ex) landing on 2 feet, rotation

non- contact- body parts not in contact ex) hang with bent legs, piked legs, stride legs

actions- independent or as a sequence (flexion/extension)

a) sequential- starting, middle, ending position

b) simultaltaneous- all parts move at one time

body: body shape

1) straight or bent

2) curl

3) stretch or narrow

4) twist

movement variable: space

1) area

a) general (enviroment) - the room, on the ice, in the street

b) personal- kinesphere

c) apparatus

2) direction

a) forward/ backwards/ sidewards

b) up/down

3) pathway

a) straight vs curved

b) angular

c) twisted

4) level

a) high

b) low

c) medium

5) planes

a) saggital (wall)

b) frontal (door)

Horizontal (table)

movement variable: effort

1) time

• sudden- fast, accelerates or decelerates quickly

• sustained- takes long or endures, repeated

2) weight

• strong/heavy/ explosive

• light/soft/ smooth

3) space

• striaght/ direct

• flexible/ indirect (flowing)

4) flow

• free/ongoing/ sustained

• bound/ unstoppable/ interrupted

movement variable: relationship

1) individual

2) partner

3) group

4) apparatus

5) music/ rhythm/ sound

ask the question “ with whim or what does it move”