biomechanis of human movement (2)

7/28/2019 Biomechanis of Human Movement (2)

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BIOMECHANICS OF HUMAN MOVEMENT


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Biomechanics combination of thesciences of applied anatomy &mechanical physics, focuses on the

forces & movement techniquesassociated with performanceenhancement & injury prevention in

sports, exercise & other motionactivities.


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Application of mechanical principles

in the study of living organisms.

Mechanics branch of physics thatanalyzes the actions of forces on

particles & mechanical systems.


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Static branch of mechanics

dealing with systems in a constant

state of motion. Dynamics branch of mechanics

dealing with systems subject to

acceleration.


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Kinematics study of thedescription of motion in term ofposition (displacement), velocity &

acceleration. Kinetics study of the action of

forces.


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Linear motion point-to-point,straight line movement of a body in

space Angular motion measurement of

how a rigid lever rotating about an

axis & its quantified through the useof polar coordinate system


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Scalar values variable that can be

described in terms of magnitude only.

Vector values magnitude that ismeasured in particular direction/along

an axis/plane.


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Velocity, acceleration, speed,

deceleration, distance, displacement.

Sports biomechanics how athletesgenerate the mechanical techniques for

successful performance.


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BASIC BIOMECHANICAL ANALYSIS OF MOVEMENT ACTIVITIES

SPRINTING

2 major phases :

Support phase Swing phase


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Support phase high muscle forces are

generated to accelerate or maintain the

sprinters velocity

Swing phase runner is airborne & the leg

segments are in recovery, one preparing to

strike the ground the other beginning to

swing forward from a position behind thebody.


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Over striding results in slowerrunning velocity.

Stride rate is the number taken perunit

Stride length is he distance asmeasured along the ground

between foot positions at takeoff &landing for the same foot.


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To create a high stride rate with an

appropriate stride length fast

rotation of the leg segments aroundthe joints.


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Upper leg must be able to rotate

rapidly around the hip joint in the

bodys sagittal plane in bothflexion & extension.


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The flexion motion is important in the

recovery of the upper leg during the

swing phase, the extension is

important for moving the leg & foot to

the ground.


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The flexion motion begins beforethe foot loses contact with the

ground & continues until the upper

leg reaches its maximum flexion knee lift recovery.


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The faster the this action

completed the shorter the swing

time of the leg.


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Provided the recovery (swing) is

adequate to allow for good leg

preparation for the upcomingsupport phase (shorten the time).


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From the point of maximum hip

flexion, upper leg rotates to the

ground with the initiation of hipflexion.


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The greater the amount of hip flexion at the

end of the swing phase, the more distancethe sprinter has to accelerate the upper leg

into extension brings the foot to the ground.

Fast rotation of the upper leg around the hipjoint will enable better landing mechanics of

the foot.


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Fast rotation of the upper of the hip extension

can be maintained as the support phase

continue, sprinter is able to accelerate at a

higher rate or maintain running velocity whilerequiring a shorter time to the foot on the ground.

Shorter time on the ground increases the stride

rate


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To enhance recovery of the leg fromthe takeoff position until footcontact, knee joint must be flexed toan extreme angle & maintainedthere for a substantial portion of theswing phase.


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After take off with the hip flexing, the

knee flexes, bringing the heel close to

the buttocks shorten the leg lever

(making it easier for the hip flexor

muscles to swing the leg forward into

knee lift position)


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Angle is maintained for much of the

middle portion of the leg swing phase

and combined with near maximum

muscle activity from the hip flexors

time for leg swing is diminished.


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Sprint velocity decreases during last portion of

the race, poor swing mechanics of the leg.

Just before the ground impact of the foot,

hamstring muscles contract forcefully to haltthe knee extension that occurs at the end of

the swing phase.

Action of hamstring causes knee flexionearly portions of the support phase.


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Combination with hip extension knee

flexion reduces braking force that occurs

when the foot strikes the ground.

Braking force is a result of a forward-

moving foot at initial ground impact.


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biomechanis of human movement (2)

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