Analysis methods and tools Reading assignment: Kreighbaum, Ch 9, 17 Outline –Observing and analyzing human performance –Putting details into a broader context – the model –General analysis methods: qualitative and quantitative –Specific analysis methods and tools Kinematic: timers, videography and other imaging, electrogoniometry Kinetic: dynamometers, force transducers, force platforms, pressure sensors, accelerometers Electromyography –Examples of analysis tools in research Timer and video analysis – Harms poster during break Strain gauge and video – slides on bat bending study Accelerometry – tennis vibration study

Observing and Analyzing Performance The Nature of Skills –Movement patterns - a general series of movements having common elements. Ex: running, jumping, walking, throwing, striking, pushing –Skill - adaptation of general movement pattern to constraints of a particular task. Ex: high jump, baseball hitting, softball pitching –Technique - a particular type of the same skill. Ex: power hitter, contact hitter –Style - individual adaptations of a technique. Ex: short backswing, no stride –Constraints - limitations associated with the event. Ex: rules, equipment, environment, limitations of performer.

Observing Performance (cnt’d) Classification of Skills According to type of environment: –Open - unpredictable environment. Ex. baseball hitting, jump shot –Closed - predictable environment. Ex: free throw, golf shot, high jump Classification according to how it is done –Discrete - definite beginning and ending. Ex: jump shot, shot put, high jump Repeated discrete - assembly line, tennis forehand. (Subject to repetitive motion disorders) –Continuous - no definite beginning and ending. Ex: running, walking, work tasks

Oberving performance (cont’d) Observing Skill Performances –Discrete skills - divide into phases such as (1) preparation, (2) execution, (3) follow-through/recovery –Continuous/cyclic - select one cycle and divide it into phases. Ex: support, swing phases in walking The global analysis (holistic model) –Identify overall performance objective (OPO) –(Table next slide) When two or more objectives are identified, priority must be set (e.g., speed vs accuracy –Divide skill into discrete parts. Ex. Stance, stride, swing, follow-through –Identify the mechanical purpose (MP) of each discrete part –List the biomechanical factors and principles. Ex:: momentum conservation –List the critical features of each part - movements that must be performed for successful execution of the skill (keys to focus on, e.g., knee extended at impact) Example – article on baseball hitting

Analysis Models – the context and the why? Holistic – same as Kreighbaum, Adrian p –Read literature and use prior experience to figure out what to focus on (ex: handout on baseball hitting) Factors-results – Adrian p –Analytical, heirarchial, deterministic –Only useful for goal-oriented skills –Example – article by Hay on swimming starting techniques

Analysis Methods Qualitative vs quantitative –Types and precision of data needed, not the tool available, dictates selection of tool Naked-eye observational procedures –Observational plan necessary to be consistent and reliable View multiple times View from multiple perspectives Focus on parts, then whole, then parts Form a visual-mental image of the performance Use a checklist – borrow or construct your own

Constructing Analysis Checklists Procedures –Study other checklists. Refer to specific sports/skills chapters in textbooks –Read literature to determine what factors are important –List the determinants of skilled and unskilled actions –Arrange checklist in a scale (dichotomous, continuum) Common factors usually included in checklists –Location of COM relative to base of support –Width of base of support –Range and path of movement of various body segments –Sequencing of segment movements –Projection angle of objects released or struck & total body COM –Overall perception of movement’s effectiveness, smoothness, etc.

Videographic and Cinematographic Analyses Qualitative procedures –Contourograms –Point plots –Stick figures Quantitative analysis -the process (Hu-M-An) –Videotaping –Frame grabbing – converting images to digital form –Digitizing – locating segment endpoints in space and time –Calculations done by computer Applying the multiplier or converting coordinates to life size Smoothing coordinates Calculating parameters for each segment and body COM –Linear displacement, velocity, acceleration and inverse dynamics –Angular displacement, velocity, acceleration and inverse dynamics Displaying output (Digital as well as graphic)

Other Analysis Procedures Optoelectric imaging –Active or passive markers (Vicon brochure) Dynamographic analysis (slides on force platform) –Force platforms, load beams, strain gauges Accelerometric analysis (slides on racquet vibrations) –Vibrations, impacts, rapidly changing motions Electrogoniometric analysis –Joint and segment angles Electromyography –When and to what degree is a muscle active? –Fatigue estimate

Begin swing: 183 ms PC

Begin Swing 233ms PC Peak 41 ms PC Horiz Pk 38 ms PC

Beg Sw ms PC O 0 is horiz & back - 21 ms PC

Approximate position when peak bending and Peak torque occurs ~ 40 ms PC

Output of accelerometer mounted on tennis racquet handle Time domain Frequency domain Results of impact on end of racquet head on racquet handle accelerations