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Chapter 2. …Measurement. 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.
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Chapter 2 …Measurement
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
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
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
Warning signal “Go” signal Initiation of response Termination of response Reaction time Movement time Response time Performance outcome measures • Reaction time Fore period Time
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
Performance outcome measures • Reaction time (RT) • Fractionated (with EMG): • Pre-motor Time: Perceptual & cognitive processes • Motor Time: Muscle vs. inertia
Performance outcome measures • Error Scores • Who is best? A. B. C.
Accuracy Bias Consistency Performance outcome measures • Error Scores • Who is best? • Depends on whether you’re talking about
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
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
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
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
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
Performance production measures • Kinematics 3-d reconstruction of joint angles
Performance production measures • Kinematics Position-time plot
Performance production measures • http://www.usc.edu/dept/LAS/kinesiology/exsc408l/powerpoint/sldaniela/complete/sld001.htm
Performance production measures • http://www.usc.edu/dept/LAS/kinesiology/exsc408l/powerpoint/sldaniela/complete/sld001.htm Velocity-time chart
Performance production measures • http://www.usc.edu/dept/LAS/kinesiology/exsc408l/powerpoint/sldaniela/complete/sld001.htm Angle-angle diagram
Performance production measures • Our diagrams – both for a free throw at basketball
Elbow Knee Performance production measures Extension 1 8 6 3 7 4 5 Knee 2 Flexion Flexion Elbow Extension
Ball release Finish Position-time plot Start Angle-angle diagram
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?