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Copy of The Biomechanics of a Free Throw

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Hayden Miller

on 14 April 2014

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Transcript of Copy of The Biomechanics of a Free Throw

The Biomechanics of a Free Throw
Phases of a Free Throw
1. Preliminary Movements
2. Backswing
3. Force Producing Movements
4. Critical Instant
5. Follow Through
What is a Free Throw?
In basketball, it is...
"an unopposed attempt to score points from a restricted area" (5.8m from the baseline i.e. the free throw line)
awarded when a player is fouled during the act of taking a shot
worth 1 point
Magnus Force and Friction
the force that results from differing air pressures around a projectile (i.e. a basketball) and causes it to have a higher or lower trajectory
in a free throw, the follow through stage causes underspin on the basketball. In turn, this creates an area of high pressure under the ball and causes the ball to have a higher trajectory
"the magnus force is proportional to spin frequency, air velocity, and the value of the drag coeffecient at the ball's velocity" (i.e. friction)
1. Preliminary Movements
2. Backswing
3. Force Producing Movements
4. Critical Instant
Instant of ball release, shot no longer affected by shooter:
The trunk and legs are fully extended, the shooting shoulder is at 140-180 degrees of flexion (nearly perpendicular to the ceiling) --> this allows greater transfer of vertical forces to ensure optimum vertical velocity of the ball
At release, the elbow is approaching full extension and the wrist is in mid flexion --> both joints are at maximum angular velocities
Completion of wrist flexion provides the final impulse for the release of the ball in addition to helping determine both velocity and the angle of projection of the ball
The non-shooting hand drops off just prior to release
Most of the power is generated from elbow and wrist flexion at release
During release of ball, relaxation of muscles in shooting arm ensures the least amount of energy is required and results in a smooth shot (no excessive tension: minimal muscle activation period - least impulse)
The wrist, forearm, upper arm, and shooting side of body should end up in a straight line and perpendicular to the floor
5. Follow Through
All joints continue to move to end of their full ROM:
The legs are fully extended, ankles plantarflexed, trunk vertical and shooting hip lined up with knee, ankle, and joints of shooting arm
Full extension of elbow and wrist allows for application of upward force and spin to ball helps stabilize the flight of the ball
Axis of Rotation
a point about which a segment rotates
In the body there are a multitude of axes of rotation
In a free throw, the movements are in the transverse axis while rotating in the sagittal plane
there are many points in the body that are a centre of rotation involved in a free throw:
through the knees
through the hips
through the shoulders
through the elbows (separately)
through the wrists (separately)
Centre of Mass
The point in the body where the distribution of masses is equal to zero
In a free throw, the entire body's centre of mass moves mostly in vertical directions
The various segments' centre of mass rotate about an axis to create torques in sequence in order to complete the free throw
Injuries
Foot- Rolling over and possibly dislocating
Muscle Torque and Moment of Inertia
produce more momentum by summing the moments of inertia of different segments together simultaneously
Control and Accuracy
Optimal release angle to enhance distance is typically 45 degrees
This is called the kinetic chain as discussed in lecture
Knee- With all of the twisting and turning, many ligaments can be torn or at least partially torn (ACL,MCL,PCL)
Back- This includes upper and lower back. Bending and twisting can cause back injuries. Also, hard impacts or falling can cause back muscles to stiffen. A problem specifically with the free throw can can be excessive lumbar lordosis which can cause lower back strain
Ankle- This is the most common injury in basketball due to overuse when weaving in and out. Also the ankle can be rolled.
There are of course many different types of injuries that can occur while playing any sport. Some main injuries while playing basketball are:
The example of the graph below is an example of just a throw but this can be applied to our free throw example
If we think about each part that is being applied in sequential order, starting at the ankle, knee, hip, trunk, shoulder, elbow, wrist and finally ending at the hand
There are a lot of different torques being applied in order to produce enough force to propel the ball up and out in a straight and parabola shape for maximum control and accuracy
However in a free throw, this is not the angle we wish to use
The optimal release angle is 50-55 degrees because we are not looking to throw a long distance, but to make a high parabola in order to keep the ball from touching the rim to avoid it bouncing out of the basket
The optimal vertical velocity is from 6 to 6.3 m/s
The hand must stay straight until complete release in order to keep control of the direction of the ball in a straight line
Leyland, T. Tennis Biomechanics 2013
Common Sports Injuries.com. (N.D.)
Retrived from http://www.commonsportsinjuries.com/bysport/basketball/
Alexander, M. (N.D.) Mechanics of the Basketball Free Throw
Retrived from http://umanitoba.ca/faculties/kinrec/research/media/free_throw.pdf
Inversion Sprain
Hand Follow Through Allows Straight Shot
The Kinetic Chain
Fix My Foot. (N.D.)
Retrieved from http://footanklealliance.com/blog/foot-ankle-doctors-los-angeles/
Mental rehearsal
Attempt to relax muscles of tension (focused breathing)
Alignment: Shooting side toe on free throw line
Non-shooting side foot may be aligned with right or slightly staggered
Feet generally close to shoulder width apart
(to ensure adequate base of support) --> if too wide, there is an additional lateral component of the feet pushing on floor as feet pronate


-
Crouch and preparation for shot:
The ball is held stationary at waist level with the shooting hand behind the ball, the fingers are well spread - ball sits on base and pads of fingers; non-shooting hand is placed on side of the ball, slightly behind center -->this allows for forward rotation of shooting shoulder when aligning to basket and prevents forward rotation of non-shooting shoulder
The trunk should be relatively square to the basket, however not perfectly square: allowing for trunk rotation ensures shooting side is forwards and non-shooting shoulder is backwards
The shooting shoulder is close to zero degrees (no flexion/extension) and is parallel to body
The knees are flexed to approximately 90 degrees, and trunk flexion is around 50 degrees from the vertical
The ball is raised to shoulder level by shoulder flexion, the upward acceleration as a result of simultaneous trunk extension creates a downwards force (because the trunk constitutes 50% of the body's mass)
Trunk flexion to extension pushes down on lumbar vertebrae, then on sacroiliac joints, and finally on hip joints --> the legs are loaded by this downward force which is transmitted to knee and ankle joints resulting in their flexion (an example of the kinetic chain discussed in lecture)
The overall combination of these movements results in the lowering of the body's center of gravity
Production of an upward and forward force which will propel ball to basket:
There is knee and hip extension, as well as further shoulder flexion until the upper arm becomes almost parallel to the floor; at the same time, elbow flexion increases close to 130 degrees and the wrist is positioned into hyperextension in order to increase the range of motion for the subsequent extension
The upper arm is raised vertically through increased shoulder flexion and this produced much of the upward force for the elevation of the ball (the balls vertical velocity)
Elbow is kept directly under the ball and tucked relatively close to the torso to minimize any lateral movements of the ball while ensuring it is pushed upwards to the basket
Wrist flexion produces backspin on the ball as it moves up the fingers to the fingertips during release
The sequence of upper body movements is as follows: trunk extension --> shoulder flexion --> elbow extension with simultaneous wrist flexion
Newton's First Law
“An object will remain at rest or continue to move with constant velocity as long as the net force equals zero”
In the free throw, by generating the forces required for the shot, the shooter goes from rest into a state of a vertical motion



Newton's Third Law
"For every action, there is an equal and opposite reaction”
During the free throw’s backswing stage, the shooter applies a downward force to the ground and the equal and opposite ground reaction force creates the force-producing movements of the free throw
Newton's Second Law
“The acceleration of an object is proportional to the net force acting on it and inversely proportional to the mass of the object”
The shooter must apply very specific forces, in a certain order (from largest to smallest muscles), to accelerate the ball through an ideal parabolic pathway


Richards, H. What are the Biomechanical Principles of a Free Throw? Saturday April 20, 2013.
Retrived from biomechanicsoffreethrow.blogspot.ca
References
BeastTV123. (2013, January 17).
Dwight Howard Airballs A Free Throw in the Clutch Vs Heat 1/18/13.
Retrieved from "https://www.youtube.com/watch?v=Vz6ARZqznj"
Note: To visit the video, type "w" at the end of the link. This was to ensure the link would remain a link instead of importing a video.
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