Movement Planning - PowerPoint PPT Presentation

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Movement Planning

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Open Skill - Tennis Serve. Served to outside corner. Directly at receiver. Flat serve ... Tennis Serve. A ball served at 90 mph will reach receiver in 660 ms ... – PowerPoint PPT presentation

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Title: Movement Planning


1
Movement Planning
2
  • After 90 grueling minutes of regulation and 30
    minutes of overtime, the score was tied USA 0,
    China 0. The 1999 Womans Soccer World Cup would
    be decided by penalty kicks. China shot first,
    they were up by 1. U.S. captain Overbek answered
    back. Next, China and the U.S. were equally
    successful, tying it up at 2-2. This brought up
    Ying. As her kick shot towards the left side of
    the goal, the U.S. goalkeeper, Briana Scurry,
    dove with outstretched arms, making an amazing
    save that sent the record crowd of 90,000 into a
    frenzy. The U.S. then went ahead 3-2 with the
    next kick. Chinas Zhang beat scurry with the
    4th penalty shot while Mia Hamm answered, putting
    the U.S. ahead once again. The final kicker for
    China put her shot far left of Scurry, tying the
    game at 4-4. The hopes of the U.S. team rested on
    the 5th and final kicker, Brandi Chastain. The
    packed stadium was silent as they watched her
    approach the ball. She drilled it off her left
    foot. The Chinese goalkeeper responded but she
    was too late. The ball soared past her, and
    history was made USA 5, China 4.

3
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4
Planning a Response
  • Stimulus Response Response
  • Identification Selection Programming

Backhand is initiated
Backhand is chosen
The ball is perceived
5
Movement Preparation
  • What is so important about getting ready to
    perform a skill?
  • What makes preparation
    such a critical part of
    successful performance?

6
Planning a Response
  • RT is not constant
  • As demands increase, time to prepare increases -
    delay can be detrimental!

7
Planning a Response
  • What factors influence how long it takes to
    prepare an action or how well this is done?
  • If a person is prepared, how long can the person
    maintain this readiness?

8
Task-Related Variables Affecting RT
  • Movement Complexity
  • Number of Choices
  • Movement Accuracy
  • Predictability

9
Person-Related Variables Affecting RT
  • Alertness
  • Practice
  • Arousal

10
Movement Complexity
Simple with 1 movement 1 reversal
Simple with 1 movement
Simple
Slower _at_ 208 ms
Slower _at_ 195 ms (sprint start)
Fastest _at_ 150 ms
11
Response Choices - Hicks Law
Reaction Speed Slows
Choices Increase
As the number of decisions increases the ability
to react slows by about 150 ms
12
Hicks Law
600
500
RT in ms
400
300
200
100
1
2
3
4
5
6
Number of Choices
13
Chastains Goal
Goalkeeper has 360 ms from time ball leaves
kickers foot to decide on response execute
movement (RT MT) before ball crosses
goal Assuming has only 2 response choices,
RT about 300 ms Leaves only
60 ms to execute response!
14
Effects of Increasing Number of Alternatives
Closed Skill
Open Skill
15
Closed Skill - Putting
  • Stimulus contrast
  • As contrast RT
  • Number of environmental features
  • Break
  • Speed of surface
  • Distance
  • Direction
  • Practice

16
Open Skill - Tennis Serve
Flat serve Directly at receiver Served to outside corner
Effects of increasing number of serves
Fast Ball Directly at receiver Served to outside corner
Slice serve Served to inside corner Served to outside corner
17
RT and Tennis Serve
  • Server Distance 60 ft Receiver

18
Tennis Serve
A ball served at 90 mph will reach receiver in
660 ms
20 ft
20 ft
20 ft
220 ms
220 ms
220 ms
19
Hicks Law
Practical examples??
20
Practical Implication?
  • Increase repertoire to increase choices for
    opponent
  • Reduce uncertainty by systematically organizing
    and prioritizing choices

21
Strategies for Improving RT
  • Increasing the size, contrast intensity of the
    stimulus
  • Practice under a variety of stimulus conditions
  • If possible simplify the movement
  • Precue participants on what to expect
  • Teach participants to anticipate

22
Anticipation
  • Predicting from current information
    into the immediate future
  • Event anticipation (what)
  • Spatial anticipation (where)
  • Temporal anticipation (when)
  • The more predictable the
    more accurate response

23
Teaching Athletes to Anticipate
  • Practice in varied situations so better know
    what, where when an event will happen
  • Detect precues for particular responses
  • Prepare for most likely events
  • On the flip side
  • Athletes must vary strategy
  • Avoid signaling movements

24
Practical Applications
  • Practice to recognize cues tendencies
  • Prepare learner to respond
  • Warning signal like set command
  • Toss of ball in serve
  • Vary foreperiod or warning signal
  • Interval time should range from 1 - 4 seconds for
    prediction and precision
  • Randomize foreperiod length to decrease
    anticipation

25
The Fake
  • RT slower for second response
    then for first response
  • Successful fake
  • Must be realistic
  • Timing is critical
  • Comes with practice
  • Practice allows reading
    fakes better

26
The Fake
Stimulus 1 (Fake)
Response 1 (Respond to Fake)
Response 2 (Response to actual move)
Stimulus 2 (Actual move)
Delay
27
Stimulus-Response Compatibility
  • Extent to which stimulus response naturally
    related
  • If low - increased preparation time
  • If high - decreased preparation time

28
Accuracy Movement
  • Fitts Law
  • Speed accuracy trade-off

3 factors influence accuracy Distance Movement
Speed Accuracy Requirement
29
Distance
A
B
Increased distance increased movement time
30
Target Size
A
B
Smaller targets increased movement time or
decreased accuracy
31
Improving Accuracy in Skills
Distance move closer to net choke down on
racket short handle racquet Target Size larger
ball larger racket face increase
boundaries Increase time to Respond ball speed
32
Improving Accuracy in Skills
Distance move closer to hole choke down on
putter Target size larger ball increase size
of hole
33
Improving Accuracy in Skills
  • Should we teach speed or accuracy first?

34
Reducing Response Time
  • Reducing Movement Time
  • Increase speed of movement
  • Reduce length of movement
  • Self-defense no back arm movement
  • Hockey shot in front of net no backswing
  • Increase distance between performer and opponent
  • Receiving serve behind baseline
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