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 Woman’s 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. China’s 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.

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 @ 208 ms Slower @ 195 ms (sprint start) Fastest @ 150 ms

11. Response Choices - Hick’s Law Reaction Speed Slows Choices Increase As the number of decisions increases the ability to react slows by about 150 ms

12. Hick’s Law 600 500 RT in ms 400 300 200 100 1 2 3 4 5 6 Number of Choices

13. Chastain’s Goal Goalkeeper has 360 ms from time ball leaves kicker’s 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 Effects of increasing number of serves

17. RT and Tennis Serve ServerDistance = 60 ftReceiver

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. Hick’s 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