Chapter 2

1. Chapter 2 …Measurement

2. Why measure? • Without measurement, how can you reliably assess progress in… • Learning? • Recovery? • …or even assess current performance strengths and weaknesses? • Idea behind this bit is to introduce some assessment methods used in motor learning and performance

3. Two measures of performance • Performance outcome measures • FG%; QB rating; Time for 40m dash • Result only – do not indicate movement used to achieve the result • Performance production measures • Joint angle changes, position-time graphs, EMG traces • Focus on descriptors of the movement used to achieve the result • See table 3.1, p. 24

4. Performance outcome measures • Reaction time • Time from presentation (“onset”) of stimulus to the start (“initiation”) of the movement • Initiation refers to observed or measured physical movement, and is usually particular to the measurement device • Example: • 100m sprint

5. Warning signal “Go” signal Initiation of response Termination of response Reaction time Movement time Response time Performance outcome measures • Reaction time Fore period Time

6. Performance outcome measures • Reaction time (RT) • 1 signal, 1 action: simple RT • More than 1 signal, more than one action: choice RT • More than 1 signal, only one requiring a response: discrimination RT

7. Performance outcome measures • Reaction time (RT) • Fractionated (with EMG): • Pre-motor Time: Perceptual & cognitive processes • Motor Time: Muscle vs. inertia

8. Performance outcome measures • Error Scores • Who is best? A. B. C.

9. Accuracy Bias Consistency Performance outcome measures • Error Scores • Who is best? • Depends on whether you’re talking about

10. Thrower Throw attempts Target line Performance outcome measures • Error Scores – 1-dimensional versions • Accuracy – absolute error (AE) • Average of positive deviations from the target So AE = the average length of these lines

11. Thrower Throw attempts Target line Performance outcome measures • Error Scores – 1-dimensional versions • Bias – constant error (CE) • Average deviation (+/- both count) So CE = average position – either a “bit” short or a “bit” long

12. Thrower Throw attempts Target line Performance outcome measures • Error Scores – 1-dimensional versions • Consistency – variable error (VE) • Grouping - how close are throws to each other? So VE = clustering

13. Accuracy Bias Consistency Performance outcome measures • Error Scores – 2-dimensional versions • Radial error & others • Same general thing, but computationally more tricky – similar concepts of bias, consistency, and accuracy

14. Target line Path taken Performance outcome measures • Error Scores – continuous skills • Root-mean-square-error (RMSE) • Like a longer version of AE The RMSE is roughly the average length of all the vertical lines

15. Performance production measures • Kinematics 3-d reconstruction of joint angles

16. Performance production measures • Kinematics Position-time plot

17. Performance production measures • http://www.usc.edu/dept/LAS/kinesiology/exsc408l/powerpoint/sldaniela/complete/sld001.htm

18. Performance production measures • http://www.usc.edu/dept/LAS/kinesiology/exsc408l/powerpoint/sldaniela/complete/sld001.htm Velocity-time chart

19. Performance production measures • http://www.usc.edu/dept/LAS/kinesiology/exsc408l/powerpoint/sldaniela/complete/sld001.htm Angle-angle diagram

20. Performance production measures • Our diagrams – both for a free throw at basketball

21. Elbow Knee Performance production measures Extension 1 8 6 3 7 4 5 Knee 2 Flexion Flexion Elbow Extension

22. Ball release Finish Position-time plot Start Angle-angle diagram

23. Summing up… • Go over those last few slides enough times to allow yourself to “get it”…if you still don’t, then try mapping out a few movements yourself, or move on to the online discussion. • OK?