Chapter 13 Biomechanical Analysis to Improve Technique

Chapter 13Chapter 13

Biomechanical Analysis to Biomechanical Analysis to Improve TechniqueImprove Technique

Forms of MotionForms of MotionForms of MotionForms of Motion

General motion General motion Linear (translation) motionLinear (translation) motion

– Rectilinear motion Rectilinear motion - motion along a straight - motion along a straight line.line.

– Curvilinear motion Curvilinear motion - motion along a curved - motion along a curved line. line.

Angular motion (fixed point)Angular motion (fixed point)

Keys Areas of StudyKeys Areas of Study

KinematicsKinematics – study of the time and space – study of the time and space aspects of movementaspects of movement

KineticsKinetics – study of the force and energy – study of the force and energy aspects of a performance.aspects of a performance.

KineticsKinetics

Kinetics Kinetics - the study of forces.- the study of forces. Basic concepts related to kinetics:Basic concepts related to kinetics:

– MassMass - the quantity of matter a body possesses. - the quantity of matter a body possesses.– InertiaInertia - resistance to a change in state of - resistance to a change in state of

motion. Directly proportional to mass.motion. Directly proportional to mass.

Qualitative Analysis of Human Movement

Qualitative Analysis of Human Movement

Requires knowledge of the Requires knowledge of the specific specific biomechanical purposebiomechanical purpose of the movement of the movement and the ability to detect the and the ability to detect the causes of errorscauses of errors..

Visual observation.Visual observation.

Analyzing Skills QualitativelyAnalyzing Skills QualitativelyAnalyzing Skills QualitativelyAnalyzing Skills Qualitatively

Analyze Analyze techniquetechnique and and outcomeoutcome..

If technique (process) is correct, outcome If technique (process) is correct, outcome

(product) will be too.(product) will be too.

Analyzing Skills QualitativelyAnalyzing Skills Qualitatively

Too frequently we coach or teach to the Too frequently we coach or teach to the outcome rather than the technique or outcome rather than the technique or process that produces the outcome.process that produces the outcome.

Role of Movement AnalystRole of Movement Analyst

Bob Norman (1976) & Shirl Hoffman (1977)Bob Norman (1976) & Shirl Hoffman (1977)

Recognize Recognize symptomssymptoms of malperformance of malperformance– Is performance acceptable? Is performance acceptable? Is the goal attained?Is the goal attained?

» Process vs ProductProcess vs Product

Trouble-shoot the Trouble-shoot the causecause of the malperformance of the malperformance» Critical ability lackingCritical ability lacking

» Skill performance deficiencySkill performance deficiency

» Psychosocial problemPsychosocial problem

Prescribe Prescribe cues to correct cues to correct malperformancemalperformance– Make the appropriate interventionMake the appropriate intervention


Hoffmann flow chartHoffmann flow chart

Was goal attained?

Define and clarify new goal

Critical ability lacking?

Skill performance deficiency?

Psycho-social problems?

Redefine goal

Remedy deficit

Technique error?

Perceptual error?

Decisionerror?

Cause of error known?

Modifytechnique

Refocus attentionon relevant stimuli

Emphasize temporalfactors

Performance managementtechniques

Yes

Yes

Yes

No

No

No

Yes

No

No

Y Yes

Yes

Yes

Yes

Ample observations?Adequate info base?

No

Critical ability lackingCritical ability lacking

If there is a mismatch between the individual and the environment - modify the environment

Mismatched EnvironmentMismatched Environment

Adapt the environment to the individual to enhance chances of success.

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

Was goal attained?





Redefine goal

Remedy deficit

Technique error?

Perceptual error?

Decisionerror?


Modifytechnique




Yes

Yes

Yes

No

No

No

Yes

No

No

Y Yes

Yes

Yes

Yes


No

Skill Performance DeficiencySkill Performance Deficiency

We will come back to this shortlyWe will come back to this shortly

Was goal attained?





Redefine goal

Remedy deficit

Technique error?

Perceptual error?

Decisionerror?


Modifytechnique




Yes

Yes

Yes

No

No

No

Yes

No

No

Y Yes

Yes

Yes

Yes


No

Psychosocial problems.Psychosocial problems.

Psychosocial problems.Psychosocial problems.

I joined a health club last year, spent about $400 and haven’t lost a pound.

• Apparently, you have to show up.

Psychosocial problems.

Bob NormanBob NormanBob NormanBob Norman

““One of the most difficult problems which One of the most difficult problems which confronts coaches and teachers when they confronts coaches and teachers when they are teaching fundamental skills is that of are teaching fundamental skills is that of detecting errors detecting errors accuratelyaccurately and and specificallyspecifically.”.”


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


Causes, symptoms and idiosyncrasiesCauses, symptoms and idiosyncrasies CauseCause – the actual mechanical reason for a – the actual mechanical reason for a

movement. Forces, acceleration, etcmovement. Forces, acceleration, etc SymptomSymptom – a side-effect of a movement. – a side-effect of a movement.

Follow through.Follow through. IdiosyncrasyIdiosyncrasy – something that occurs during – something that occurs during

movement that has nothing mechanically to movement that has nothing mechanically to do with the movement. Tongue sticking outdo with the movement. Tongue sticking out

Bob NormanBob Norman

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

Skill Performance DeficiencySkill Performance Deficiency

Mechanical Mechanical objective of a skillobjective of a skill» momentummomentum in particular direction(s) in particular direction(s)

Bob Norman (1976)Bob Norman (1976)

Mechanical Mechanical objective of a skillobjective of a skill IdiosyncrasyIdiosyncrasy

– individual nuance of performance that has no individual nuance of performance that has no direct influence on direct influence on mechanicsmechanics of performance of performance

» Michael Jordan’s tongueMichael Jordan’s tongue

» Various batting stancesVarious batting stances

How Often Have You Heard This?How Often Have You Heard This?

You need to stand ____ with the bat ______ You need to stand ____ with the bat ______ to hit the ball.to hit the ball.

Unwarranted focus on static position of batting stance

Some People Just Don’t Get It? 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 NYLetter to the editor, Discover magazine.


Mechanical Mechanical objective of a skillobjective of a skill IdiosyncracyIdiosyncracy Symptom of an errorSymptom of an error

– what we see go wrong (kinematics)what we see go wrong (kinematics)» not high enoughnot high enough

» not fast enoughnot fast enough

» wrong directionwrong direction

» body positionsbody positions

How Often Have You Heard This?How Often Have You Heard This?

Swing levelSwing level

Paul PopovichMarch 29, 1993.

Swing

Level?

Say what you mean!

Another ExampleAnother Example

The Follow ThroughThe Follow Through

Basketball shooting - “Goose neck”Basketball shooting - “Goose neck”

Follow through?Follow through?

““As the knees straighten, release the ball and follow through with a flick of the As the knees straighten, release the ball and follow through with a flick of the wrist”wrist”

““Follow through by snapping your wrist down, like you are reaching into the Follow through by snapping your wrist down, like you are reaching into the cookie jar.”cookie jar.”

““As you release the ball, snap your wrist downward, as if you are waving 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 "good-bye" (called a "follow through"). When done correctly, the wrist snap will give the ball the correct amount of spin it needs.”will give the ball the correct amount of spin it needs.”

FollowFollowthroughthrough

Game-winning shot vs Utah Jazz 19**???

Symptomor

Cause?

Another ExampleAnother Example

Pitchers are told to “lead with the elbow”Pitchers are told to “lead with the elbow”

Lead with the elbow

ShoulderExternalRotation:

Symptom?orCause?of GreatPerformance?


Mechanical Mechanical objective of a skillobjective of a skill IdiosyncracyIdiosyncracy Symptom of an errorSymptom of an error Cause of an errorCause of an error

– the underlying reason for the poor performancethe underlying reason for the poor performance» mechanically: error in mechanically: error in impulse applicationimpulse application

Mechanical Phases Mechanical Phases of skill performanceof skill performance

Ritual PhaseRitual Phase– Full of idiosyncrasies, useful for mental focusFull of idiosyncrasies, useful for mental focus

PreparationPreparation– Wind upWind up

» Storage of elastic energy, increase ROM (Benefits?)Storage of elastic energy, increase ROM (Benefits?)

ExecutionExecution– AccelerationAcceleration

» Apply impulse to the Apply impulse to the bodybody in the desired direction in the desired direction

Follow throughFollow through– Bring moving parts to restBring moving parts to rest

» Safety, symptom of good performanceSafety, symptom of good performance

Typical Coaching AdviceTypical Coaching Advice




More Glaring Examples of Bad More Glaring Examples of Bad CoachingCoaching

Volleyball Underhand ServeVolleyball Underhand ServePeer Rating Evaluation SheetPeer Rating Evaluation Sheet

from a middle school session at IAHPERD conferencefrom a middle school session at IAHPERD conference

1. Is the arm which is holding the ball across the front of the body? 2. Is the ball held at or below the waist?3. Is the body bent at the waist before the person hits the ball?4. Is the striking arm brought back with a straight elbow?5. Is the ball hit from a short toss or out of the hand?6. Does the hitting arm swing from the shoulder?7. Does the hitting arm swing straight, not across the body?8. Is the person stepping or standing with opposition?9. Is there a weight shift from the rear foot to the front foot when

the ball is hit?10. Does the striking hand follow through at least as high as the head

after the ball is hit?

Possible reasons why the elderly Possible reasons why the elderly walk slowerwalk slower

Not willing to walk fasterNot willing to walk faster– Wise enough to know that walking faster changes nothingWise enough to know that walking faster changes nothing– Careful stepping due to slowing of reflexesCareful stepping due to slowing of reflexes– CautiousCautious– Afraid of road hazardsAfraid of road hazards– Afraid of falls due to OP, other catastrophesAfraid of falls due to OP, other catastrophes

Not able to walk faster Not able to walk faster – Reduced ability to maintain dynamic balanceReduced ability to maintain dynamic balance– Reduced ROMsReduced ROMs– Reduced contents of fast-twitch muscle fiberReduced contents of fast-twitch muscle fiber– Joint or muscle pathologiesJoint or muscle pathologies– Reduce CV fitnessReduce CV fitness

Help! I’ve Fallen and I Can’t Get UpHelp! I’ve Fallen and I Can’t Get Up

PhenomenonPhenomenon– Individual cannot rise from the groundIndividual cannot rise from the ground

» After a fallAfter a fall» GardeningGardening» HousecareHousecare

– Why not? List possible reasons, according to the Hoffman Why not? List possible reasons, according to the Hoffman ChecklistChecklist

Importance: Develop an intervention for preventionImportance: Develop an intervention for prevention» Strength training?Strength training?» Flexibility training?Flexibility training?» Technique TrainingTechnique Training

• What technique? Old vs Young? Healthy vs Infirm? What technique? Old vs Young? Healthy vs Infirm?


Understand the specific purpose of the skill Understand the specific purpose of the skill from a biomechanical perspective.from a biomechanical perspective.

Identify the cause of technique error.Identify the cause of technique error.

Familiarity with the skill aids in analysis.Familiarity with the skill aids in analysis.

Planning a Qualitative AnalysisPlanning a Qualitative AnalysisPlanning a Qualitative AnalysisPlanning a Qualitative Analysis

Identify the major questions of interest Identify the major questions of interest (What is the problem?). (What is the problem?).

Determine the optimal perspective from Determine the optimal perspective from which to view the movement. which to view the movement.

Select the optimal viewing distance.Select the optimal viewing distance.

Planning a Qualitative AnalysisPlanning a Qualitative AnalysisPlanning a Qualitative AnalysisPlanning a Qualitative Analysis

Determine the optimal number of trials Determine the optimal number of trials necessary to perform the analysis.necessary to perform the analysis.

Determine the effect of environmental Determine the effect of environmental factors on performance. factors on performance.

Will a video recording help in analysis?Will a video recording help in analysis?

Conducting a Qualitative Conducting a Qualitative AnalysisAnalysis


Every performance of a motor skill is Every performance of a motor skill is affected by the physical characteristics of affected by the physical characteristics of the performer.the performer.

Conducting a Qualitative Conducting a Qualitative Analysis Analysis

Conducting a Qualitative Conducting a Qualitative Analysis Analysis

These include the performer's critical These include the performer's critical abilities:abilities:– age,age,– gender,gender,– anthropometrics, anthropometrics, – the developmental and skill levels at which the the developmental and skill levels at which the

performer is operating, performer is operating, – and any special physical or personality traits and any special physical or personality traits

that may impact performance. that may impact performance.



Providing a novice, preschool-aged Providing a novice, preschool-aged performer with cues for a skilled, mature performer with cues for a skilled, mature performance may be counterproductive, performance may be counterproductive, since children are not simply scaled-down since children are not simply scaled-down adults.adults.



The analyst should not overlook the The analyst should not overlook the potential value of non-visual forms of potential value of non-visual forms of information (sound). information (sound).

Another potential source of information is Another potential source of information is feedback from the performer.feedback from the performer.



Adding more than one analyst may enhance Adding more than one analyst may enhance the thoroughness of the analysis.the thoroughness of the analysis.

Quantifying KineticsQuantifying Kinetics

Tools for measuring kinetic quantities:Tools for measuring kinetic quantities:– EMGEMG– DynamographyDynamography– Force platformsForce platforms



Tools for measuring Tools for measuring kinematic quantities:kinematic quantities:Cinematography and Cinematography and

videography.videography.

Optoelectric movement Optoelectric movement monitoring systems monitoring systems (LEDs)(LEDs)


Electrogoniometers.Electrogoniometers.

Timing devices.Timing devices.

Accelerometers.Accelerometers.

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Chapter 13 Biomechanical Analysis to Improve Technique