Qualitative Biomechanics

5/26/2018 Qualitative Biomechanics

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Qualitative Biomechanics

Kathleen MacLean

March 18, 2014

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Movement Assessments

! Work of the Biomechanist! Assess movement! In a variety of settings

! Depending on the setting, form of assessment may change! Quantitative! Qualitative


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+Quantitative vs. Qualitative

! Quantitative! Objective properties! Information based on quantitiesof data! Measured

! Qualitative! Subjective properties! Information based on a characteristic or qualities! Observed

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Quantitative Movement Assessment

! The tools


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+Qualitative Movement Assessment

Systematic observationand introspective judgment of the

quality of human movement for the purpose of providing the

most appropriateinterventionto improveperformance

*Using biomechanical principles and knowledge

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Qualitative Biomechanics

! Used to analyze:! Why we move the way we do! Improve performance! Reduce injury rates! Clinical diagnosis! Skill analysis! Error detection


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+Movement Assessments

! Quantitative does not equal validity or reliability! Qualitative does not equal invalid or unreliable

! Different forms of qualitative analysis! Choice depends on the movement and purpose of analysis,

experience of evaluator, setting, age and ability of performer

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Where do Assessments Occur

! Schools! Physical Education

! Clinics! Rehabilitation or training

! Sports! Performance or injury assessment

! Occupational Settings! Productivity, injury and fatigue rates

! Lab! During quantitative assessments


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+Qualitative Assessment in Phys Ed

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Qualitative Assessment in Sports

! Coaching!Athletic therapists


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+Qualitative Assessment in Clinics

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Qualitative Assessment in Ergonomics


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+Qualitative Assessment

! Might seem subjective! But organized, specific! Requires planning, interdisciplinary information, and systematic

steps

! Interdisciplinary! Integrate many perspectives

! Done correctly, provides important information aboutmovement

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Qualitative Biomechanical Assessment

! So how do we go about performing a systemic qualitativemovement assessment?

! Outline and follow steps to analysis! Grounded in biomechanical knowledge and terminology! Background research


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Steps of a Qualitative Analysis

! Step 1: Preparation! Determine areas of observation to assess in individual and

environment

! Step 2: Observe! Several systematic performances of the movement

! Step 3: Evaluation! Diagnosis performance strengths and weaknesses, limitations to

performance

! Step 4: Intervention (if necessary)! Feedback, demonstrations, mimicry etc.


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+Step 1: Preparation

! Needed for appropriate evaluation! Includes! What is the objective of the task! What biomechanical principles are at play?

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Objective of the Task

! Need to consider the desired outcome (Norman, 1975)! Minimization of fatigue over an endurance or repetitive task! Maximize speed, height, distance! Force! Precision! Speed! Balance or stability! Combination?


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+Applying Biomechanical Principles

! What principles affect objective? (Norman, 1975)! Depending on the task, certain principles may be more

important to the assessment:

! Direction of force application! Stability! Conservation and transfer of momentum! Minimizing joint load! Summation of joint moment effects! Summation of body segment velocities! Optimal joint position! Minimizing fatigue

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Step 2: Observe

! Usually break the task down into stages or phases! Objective of each phase! Primary body segment(s) involved in each phase! Biomechanical principles of each phase


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+Phases

! Most movements involve three basic phases! Preparation! Execution! Follow-through

! These can be further broken down and specified for eachtask or skill

! What body segments are involved?

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Critical Features of a Skill

! Invariant technique points of a movement! Determines what is right and wrong about movement! Associated with each phase of movement

! What cues are necessary for optimal performance! What are the critical elements?


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+Composite Approach

! Total Body Approach! Whole body as a system! Stages of skill are based on combined product of all body parts! Descriptions for each stage

! Evaluates quality of movement

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Component Approach

! Each primary body component still observed! Each component has its own evaluative phases! More detail provided

! Error Analysis Strategy


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+Steps 3 & 4: Evaluate and Intervene

! Compare expected movement (prep) with observedmovement

! Are task objectives met?! Are biomechanical principles being violated or not exploited?

! Provide biomechanical feedback to improve performance

QualitativeAssessment

QuantitativeAssessment


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+History Lesson

! Department of Kinesiology! Previously Department of Physical Education

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Complementary

! Not competitive! What can each tell us that the other cannot! When is one not feasible, appropriate or ethical?


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+Qualitative Advantages

! Quicker, easier! Qualitative tools are unavailable or unfeasible! Qualitative often gives us an initial exploration of a

movement task or issue

! When we need more than just numbers

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Quantitative Advantages

! Provide numeric proof of applied biomechanical principles! Determine cutoffs for injury and disease prevention! Measure changes in performance of a skill or task! Determine biomechanics associated with optimization of

performance


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+Tag team

! Both processes often used for ultimate movement goal! Interplay between both forms of movement assessment! Done when analyzing all kinds of tasks and questions

! Consider rehabilitation from an injury

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Evolution

! How did we become the way we are! What adaptations occurred?! How have adaptations affected movement performance

! What differentiates us from our closest relatives?! And ancestors


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+Evolutionary Questions

! Gaps in our understanding! Few living ancestors we can observe

! Need to fill them using qualitative and quantitative analyses! What can both assessments tell us about our evolutionary

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How has the shoulder evolved?

! Why wont my dog hug me back?


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+Throwing

! Uncommon in other animals! Uniquely hominin trait! Courtesy of our bipedalism

! What was the advantage of the shoulder evolution! How do we compare to our closest living relatives?! And our ancestors?! Are we different?

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The Many Throws


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+Throwing to Hunt

! Overarm

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Chimp Throw

! Chimpanzees are decent throwers


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+Human Throw

! But theyve got nothing on humans

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Humans vs. Chimps

!Appears as though there is difference in throwing betweenhumans and chimps

! How are they different

! We can put a pitcher into a lab to make an analysis! But not a chimpanzee


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+Qualitative Biomechanical Analysis

! To perform a qualitative analysis, we need prep! Determine objectives! Determine core biomechanical principles! Break throw down into phases

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Objective & Principles of Throwing

! Objective:! Produce as much hand speed as possible! Accuracy

! Summation of body segment velocities! Proximal to distal! Maximizes end segments velocity

! Whip Effect! Principle of transfer of momentum! Generates angular motion


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+Phases of Throwing

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Windup


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+Acceleration

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Follow-Through


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+Windup

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Acceleration


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+Follow-Through

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Observed Differences

! We see the differences in movement! Result in a difference in throwing abilities! Speed! Distance

! But Why?! Consider:! Bone and muscle Morphology! Variability in human performance

! Need quantitative analyses


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+Morphological Assessment

! How do our bones differ?! Physical characteristics! Boney formation

!And how will this limit movement capabilities

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Baseball Players

! Quantitatively test the effect ofderived morphological traits in

humans (Roach et al., 2013)

! Study elite throwers! Effect of morphological traits! Effect of induce limitations on the

shoulder


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+Glenoid Orientation

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Effect of Glenoid Orientation


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+Humeral Torsion

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Humeral Torsion

!Affects Range of Motion


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+Humeral Torsion


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+The Missing Link

! What about all our ancestors in between?! How did they move?! What was the sequence of adaptation?

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Qualitative-Quantitative Tradeoff

! We cant observe our extinct ancestors move! But we can make inferences based on:! What we know about what came before and after! Us Homo Sapiens! Living relatives Chimpanzees! Fill in the gap

! Fossils! Bone Morphology! Boney orientation

! Determine potential physical capabilities


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+Quantitative Assessment

! Quantitative analyses of human throwing can help us understand thefossil record

! Morphological features that help human throwing can be assessed in thefossil record

! When did we start throwing projectiles?! Archeological evidence is divisive

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Informed by Sports Medicine

! Humeral torsion asymmetry in elite throwing athletes (Chant etal., 2007; Reagan et al., 2002; Roach et al., 2013)


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+Torsion Asymmetry

! Dominant vs. Non-dominant Arm! Paleolithic vs. Neanderthal

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Back to Qualitative Analyses

! Using quantitativedata, we can qualitativelyreconstruct anunderstanding of how our fossilized ancestors moved

! We know how quantified morphological features affectperformance

! We know the morphology of fossils

! Were our ancestors as great as throwing as us?


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The Shoulder Advantage

! Combined quantitative and qualitative assessment can tell uswhen and how humans survived

! Hominin disadvantages:! Not particularly fast, strong! Lack the teeth and claws to injure prey or protect ourselves from! Need to avoid confrontation with prey


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+The Shoulder Advantage

! Hominin Advantage:! Throwing capabilities! Endurance running capabilities! Provided through shoulder morphology! Swinging arm

! Throwing provided a means to obtain high protein food

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In The End

! Systematic qualitative biomechanical analyses provideimportant movement information

! Trade off between qualitative and quantitative analyses forcommon goal

! Understanding human movement

Qualitative Biomechanics

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