Biomechanics of Airborne and Arm-Supported Activities

8/14/2019 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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Generate sufficient torque to provideangular momentum Complete number of rotations Prepare for landing

Prepare speed and time of rotation actions


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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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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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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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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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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



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Twist for somersault The most common

technique used

Body must have angularmomentum establishedabout axis at takeoff



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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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Documents

Biomechanics of Airborne and Arm-Supported Activities