Chapter 13

1. Chapter 13 Biomechanical Analysis to Improve Technique

2. Forms of Motion • General motion • Linear (translation) motion • Rectilinear motion - motion along a straight line. • Curvilinear motion - motion along a curved line. • Angular motion (fixed point)

3. Keys Areas of Study • Kinematics – study of the time and space aspects of movement • Kinetics – study of the force and energy aspects of a performance.

4. Kinetics • Kinetics - the study of forces. • Basic concepts related to kinetics: • Mass - the quantity of matter a body possesses. • Inertia - resistance to a change in state of motion. Directly proportional to mass.

5. Qualitative Analysis of Human Movement • Requires knowledge of the specific biomechanical purpose of the movement and the ability to detect the causes of errors. • Visual observation.

6. Analyzing Skills Qualitatively • Analyze technique and outcome. • If technique (process) is correct, outcome (product) will be too.

7. Analyzing Skills Qualitatively • Too frequently we coach or teach to the outcome rather than the technique or process that produces the outcome.

8. Role of Movement AnalystBob Norman (1976) & Shirl Hoffman (1977) • Recognize symptoms of malperformance • Is performance acceptable? Is the goal attained? • Process vs Product • Trouble-shoot the cause of the malperformance • Critical ability lacking • Skill performance deficiency • Psychosocial problem • Prescribe cues to correct malperformance • Make the appropriate intervention

9. Analyzing Skills Qualitatively • Hoffmann flow chart

10. Was goal attained? Yes Define and clarify new goal No Redefine goal Yes Critical ability lacking? Yes Remedy deficit Ample observations? Adequate info base? No No Skill performance deficiency? Technique error? Cause of error known? Yes Modify technique Y Yes No Refocus attention on relevant stimuli Perceptual error? Yes No No Emphasize temporal factors Decision error? Yes Psycho-social problems? Performance management techniques Yes

11. Critical ability lacking If there is a mismatch between the individual and the environment - modify the environment

12. Mismatched Environment Adapt the environment to the individual to enhance chances of success.

13. Photo by Erica Trout in Parade Magazine, 9/19/04

14. Was goal attained? Yes Define and clarify new goal No Redefine goal Yes Critical ability lacking? Yes Remedy deficit Ample observations? Adequate info base? No No Skill performance deficiency? Technique error? Cause of error known? Yes Modify technique Y Yes No Refocus attention on relevant stimuli Perceptual error? Yes No No Emphasize temporal factors Decision error? Yes Psycho-social problems? Performance management techniques Yes

15. Skill Performance Deficiency • We will come back to this shortly

16. Was goal attained? Yes Define and clarify new goal No Redefine goal Yes Critical ability lacking? Yes Remedy deficit Ample observations? Adequate info base? No No Skill performance deficiency? Technique error? Cause of error known? Yes Modify technique Y Yes No Refocus attention on relevant stimuli Perceptual error? Yes No No Emphasize temporal factors Decision error? Yes Psycho-social problems? Performance management techniques Yes

17. Psychosocial problems.

18. Psychosocial problems. • I joined a health club last year, spent about $400 and haven’t lost a pound. • Apparently, you have to show up.

19. Psychosocial problems.

20. Bob Norman • “One of the most difficult problems which confronts coaches and teachers when they are teaching fundamental skills is that of detecting errors accurately and specifically.”

21. Bob Norman • “If the error detection is inaccurate or non-specific, the quality of instruction and the consequent learning on the part of the athletes will be poor.”

22. Bob Norman Causes, symptoms and idiosyncrasies • Cause – the actual mechanical reason for a movement. Forces, acceleration, etc • Symptom – a side-effect of a movement. Follow through. • Idiosyncrasy – something that occurs during movement that has nothing mechanically to do with the movement. Tongue sticking out

23. Bob Norman • In teaching and coaching, we too often focus on the symptoms and idiosyncrasies of a performance rather than the actual mechanics that determine what happens.

24. Skill Performance Deficiency • Mechanical objective of a skill • momentum in particular direction(s)

25. Bob Norman (1976) • Mechanical objective of a skill • Idiosyncrasy • individual nuance of performance that has no direct influence on mechanics of performance • Michael Jordan’s tongue • Various batting stances

26. How Often Have You Heard This? • You need to stand ____ with the bat ______ to hit the ball.

27. Unwarranted focus on static position of batting stance

30. Some People Just Don’t Get It? “Physics is not the only science important in the game of baseball; it’s also a game of psychology, of pitchers trying to stare down batters, and batters trying to intimidate pitchers. And no matter what you tell me, I don’t believe that some guy standing in the batter’s box with his bat dangling loosely from his hands has nearly as much power as a guy snarling and gripping the bat hard, waving it menacingly over his head. It may not be good science, but I’ll bet the second guy gets more hits.” Suzanne Sparacino, Commack NY Letter to the editor, Discover magazine.

31. Bob Norman (1976) • Mechanical objective of a skill • Idiosyncracy • Symptom of an error • what we see go wrong (kinematics) • not high enough • not fast enough • wrong direction • body positions

32. How Often Have You Heard This? • Swing level

34. Swing Level? Paul Popovich March 29, 1993.

35. Say what you mean!

36. Another Example • The Follow Through • Basketball shooting - “Goose neck”

37. Follow through? • “As the knees straighten, release the ball and follow through with a flick of the wrist” • “Follow through by snapping your wrist down, like you are reaching into the cookie jar.” • “As you release the ball, snap your wrist downward, as if you are waving "good-bye" (called a "follow through"). When done correctly, the wrist snap will give the ball the correct amount of spin it needs.”

38. Followthrough Symptom or Cause? Game-winning shot vs Utah Jazz 19**???

40. Another Example • Pitchers are told to “lead with the elbow”

41. Lead with the elbow

42. Shoulder External Rotation: Symptom? or Cause? of Great Performance?

43. Bob Norman (1976) • Mechanical objective of a skill • Idiosyncracy • Symptom of an error • Cause of an error • the underlying reason for the poor performance • mechanically: error in impulse application

44. Mechanical Phases of skill performance • Ritual Phase • Full of idiosyncrasies, useful for mental focus • Preparation • Wind up • Storage of elastic energy, increase ROM (Benefits?) • Execution • Acceleration • Apply impulse to the body in the desired direction • Follow through • Bring moving parts to rest • Safety, symptom of good performance

45. Typical Coaching Advice

46. Typical Coaching Advice

47. Typical Coaching Advice

48. Typical Coaching Advice

49. More Glaring Examples of Bad Coaching

50. Volleyball Underhand ServePeer Rating Evaluation Sheetfrom a middle school session at IAHPERD conference • Is the arm which is holding the ball across the front of the body? • Is the ball held at or below the waist? • Is the body bent at the waist before the person hits the ball? • Is the striking arm brought back with a straight elbow? • Is the ball hit from a short toss or out of the hand? • Does the hitting arm swing from the shoulder? • Does the hitting arm swing straight, not across the body? • Is the person stepping or standing with opposition? • Is there a weight shift from the rear foot to the front foot when the ball is hit? • Does the striking hand follow through at least as high as the head after the ball is hit?