Biomechanics of Karate:Biomechanics of Karate:Measuring Impact Force in Shotokan Measuring Impact Force in Shotokan

Karate StrikesKarate Strikes

Yasaman ShiraziYasaman ShiraziJanuary 26, 2007January 26, 2007

OVERVIEWOVERVIEW

PurposePurposeShotokan TechniqueShotokan TechniqueHypothesesHypothesesApparatusApparatusExperiment ProtocolExperiment ProtocolDataDataResultsResultsFuture Plans and StudiesFuture Plans and Studies

PURPOSEPURPOSE

Studying Martial Arts from an Engineering Studying Martial Arts from an Engineering PerspectivePerspectiveQuantifying Strength of Various Quantifying Strength of Various TechniquesTechniquesFinding Scientific Proof behind the Finding Scientific Proof behind the Traditional Arts and their ApplicationsTraditional Arts and their ApplicationsAssisting Proper Teaching of Shotokan Assisting Proper Teaching of Shotokan Karate StrikesKarate Strikes

REVERSE PUNCHREVERSE PUNCH

One of the Most Basic and Common One of the Most Basic and Common StrikesStrikesDelivered in 3 Orientations:Delivered in 3 Orientations:

Horizontal Horizontal –– KihonKihon (Basics)(Basics)Vertical (Jab) Vertical (Jab) –– Kumite (Sparring)Kumite (Sparring)45 Deg 45 Deg –– BunkaiBunkai (Real Life Application)(Real Life Application)

REVERSE PUNCHREVERSE PUNCH

REVERSE PUNCHREVERSE PUNCH

HYPOTHESESHYPOTHESES

Strike Effectiveness will be influenced by:Strike Effectiveness will be influenced by:ExperienceExperienceAngle of DeliveryAngle of Delivery

Horizontal Horizontal –– StrongestStrongestVertical Vertical –– FastestFastest45 Deg 45 Deg –– Most PracticalMost Practical

GenderGenderSizeSize

APPARATUS DESIGNAPPARATUS DESIGN

Criteria:Criteria:Deliver Direct Linear Impact to a Force SensorDeliver Direct Linear Impact to a Force SensorProduce No Moment if Hit OffProduce No Moment if Hit Off--centeredcenteredBe Adjustable According to Different HeightsBe Adjustable According to Different HeightsBe Robust and StableBe Robust and StableCan Be Built Within Our Time Limit and Can Be Built Within Our Time Limit and Available MaterialsAvailable Materials

DATA COLLECTIONDATA COLLECTION

2000lb Load Cell2000lb Load CellLocated Directly Behind the TargetLocated Directly Behind the Target

Motion Capture SystemMotion Capture System3 High Speed Cameras to Record the Motion3 High Speed Cameras to Record the Motion6 Reflective Markers on Joints of Interest on 6 Reflective Markers on Joints of Interest on the Subjectsthe Subjects

APPARATUS DESIGNAPPARATUS DESIGN

APPARATUS CONSTRUCTIONAPPARATUS CONSTRUCTION

EXPERIMENTSEXPERIMENTSSet UpSet Up

Calibrating the CamerasCalibrating the CamerasPilot TestingPilot Testing

EXPERIMENTSEXPERIMENTSSubjects:Subjects:

Beginner (1F, 2M)Beginner (1F, 2M)Intermediate (3F, 3M)Intermediate (3F, 3M)Advanced (3F, 3M)Advanced (3F, 3M)Read & Sign the Consent FormRead & Sign the Consent FormWarm upWarm upFree TrialsFree TrialsWear 6 Reflective MarkersWear 6 Reflective Markers

Testing ProtocolTesting Protocol3 Sets (Horiz, 45 Deg, Vert)3 Sets (Horiz, 45 Deg, Vert)5 Punches Each5 Punches Each

DATA PROCESSINGDATA PROCESSING

SIMISIMIRecording the Force DataRecording the Force DataProcessing Video Files and Tracking MarkersProcessing Video Files and Tracking Markers

C++C++Finding Peak Forces and Time of ImpactFinding Peak Forces and Time of ImpactAdjusting the Off Set of the ForceAdjusting the Off Set of the ForceImporting Data and Creating Excel FilesImporting Data and Creating Excel Files

ExcelExcelProcessing Numeric ResultsProcessing Numeric ResultsNormalizing and Finding Correlations among Different Normalizing and Finding Correlations among Different VariablesVariables

RESULTSRESULTSProcessed DataProcessed Data

Force vs. Time - 45 Deg

-300

-250

-200

-150

-100

-50

0

50

0 1000 2000 3000 4000 5000 6000

Time (ms)

Forc

e (lb

s)

RESULTSRESULTS

Overall Average Force

160

170

180

190

200

210

220

Categories

Forc

e (lb

s)

Horizontal45 DegVertical

RESULTSRESULTS

Maximum Peak Force

0

50

100

150

200

250

300

ADVANCED BEGINNER

Category

Forc

e (lb

s)

malefemale

• Comparing Force Based on Gender and ExperienceComparing Force Based on Gender and Experience

RESULTSRESULTS

-0.023-0.082-0.173-0.054-0.107Experience (Months)

0.3320.3920.5620.3180.436BMI

0.5090.1910.1680.6280.587Height (in)

0.6070.7050.5230.6860.741Weight (lbs)

0.8190.6780.3200.9020.863Grip Strength (lbs)

Ave. Impules(lb.s)

Max Impulse(lb.s)Force STD

Average F (lbs)

Max F (lbs)

Pearson Correlation Coefficient

RESULTSRESULTSImpulse = Impulse = ∫∫ F. dtF. dtAve. Impulse vs. Ave. Force Ave. Impulse vs. Ave. Force

Pearson Correlation Coefficient Pearson Correlation Coefficient = 0.8685= 0.8685

•• Y = 0.0208 x + 0.955Y = 0.0208 x + 0.955

•• RR2 2 = 0.7543= 0.7543

Average Force vs. Average Impulse

1

2

3

4

5

6

7

0 50 100 150 200 250 300

Average Force (lbs)

Ave

rage

Impu

lse

(lb.s

)

CHALLENGESCHALLENGES

Not Having Enough Support to Keep the Not Having Enough Support to Keep the Apparatus in PlaceApparatus in Place

Having OffHaving Off--set Force Dataset Force Data

Verifying if the Strike is Delivered Verifying if the Strike is Delivered CorrectlyCorrectlyHaving to Recalibrate the CamerasHaving to Recalibrate the CamerasExporting Force Data from SIMIExporting Force Data from SIMI

FUTURE STUDIESFUTURE STUDIES

Processing the Motion Capture Video FilesProcessing the Motion Capture Video FilesTesting Larger Group of SubjectsTesting Larger Group of SubjectsUsing Random CombinationsUsing Random CombinationsExperiment Different Padding or GlovesExperiment Different Padding or GlovesModifying Apparatus DesignModifying Apparatus DesignSecuring the Apparatus to the WallSecuring the Apparatus to the WallPossibly Studying Other Strikes, i.e. KicksPossibly Studying Other Strikes, i.e. Kicks……