biomechanics of airborne and arm-supported activities
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Biomechanics of Airborne and
Arm-Supported Activities
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Airborne and Arm-SupportedActivities
Performance success depends on Sufficient angular impulse to generate
optimum angular momentum Position of body Forces generated at takeoff
Complete aerial rotation and prepare for
landing Shape of projectile Time available for flight
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Basic principles of airborne andswinging activities
Eccentric force (torque) applied canproduce rotation
Aerial rotation Axis of rotation passes through CM
Swinging activities Axis of rotation through grip of hands, bars,
rings, other surfacesMomentum = Torque
= Force x Distance ()
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Basic principles of airborne andswinging activities
Generate sufficient torque to provideangular momentum Complete number of rotations Prepare for landing
Prepare speed and time of rotation actions
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Basic principles of airborne andswinging activities
Sufficient vertical height
Angular velocity can be changed by changingbody position
Flight path is determined at takeoff, cannotadjust in airborne
2
2
1ats=
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Basic principles of airborne andswinging activities
Time required depends on Body position Number of rotations Angle of takeoff
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Determinants of Skilled Movements
Amplitude Bigness of movments
External amplitude ;
range covered by CM Depends on impulse of
propulsive action
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Determinants of Skilled Movements
Amplitude (cont.) Bigness of
movments
Internal amplitude ;relative ROM of bodysegments
The greater
segmental velocityand ROM, the greaterthe ability to performcomplex elements
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Determinants of Skilled Movements
Segmentation Human body is made up of
14 segments
Skill proficiency is inverselyrelated to number ofsegments used
Any actions of segment
affects location of CM anddistribution of forcesthrough body
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Determinants of Skilled Movements
Closure Relates to internal amplitude Concerned with absolute changes in shape
Peaking Concerned with precise timing of body
changes
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Rotary Motion
CG and axis ofrotation
Angular momentum Mass Radius of gyration Angular velocity
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Initiating Rotations
Ground reactionrotations Initiate rotation around
ML (somersaulting) andlongitudinal (twisting)axes
CG is ahead of line of
action of GRF External torque iscreated about ML axisthrough performers CG
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Initiating Rotations in Air
Reaction rotation Movements of arms, legs or trunk causes
reaction or movement response of rest of
system in opposite direction
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Cat rotation Complicated version
of reaction rotation
Initiating Rotations in Air
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Twist for somersault The most common
technique used
Body must have angularmomentum establishedabout axis at takeoff
Initiating Rotations in Air
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Mechanics of Arm-Supported Skills
Rotations in vertical plane are affected bygravity Motive in descent Resistive in ascent
Rotations in horizontal plane get no motiveimpulse from gravity
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Swing
3 forces and a couple act upon W = weight R = reaction force exerted by bar
Normal (centripetal) component Tangential component
A = air resistance
M = resultant moment of frictional forces
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Swing
Weight
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Swing
Centripetal component Repeatedly change direction CG moves along curved path 4 times bw as swing under bar in giant swing
Tangential component Eccentric force; serves to accelerate in
direction about axis
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Swing
Moment
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