Major Question:
“What Biomechanical Principles are Required for Optimal and Efficient Performance and Execution of a Basketball Jump Shot?”
The Answer
Introduction
The Basketball jump-shot is a skill widely regarded as
being pioneered by the late Sailor as early as 1943 who was the first person to
shoot the ball in front of a defender by jumping and then releasing the ball (Christgau, 1999). Fast
forward to today and the reigning MVP for the last two seasons in the NBA Stephen Curry bases his game predominately on this one technique. Additionally, the basketball jump-shot is an open
skill, influenced heavily by the environmental contingencies produced within
the sport of basketball (Cortis,
Tessitore, Lupo, Pesce, Fossile, Figura, & Capranica, 2011). With this in mind, based on biomechanics research, the
following teaching sequence is designed for an intermediate player to reach
optimal performance when shooting a mid-range to long-range basketball jump
shot.
Preparatory phase
The
preparatory phase of the jump-shot plays a significant role in influencing the
success of the skill. The goal of this initial phase is to manipulate the body
into a position where the centre of gravity is fixed over the base of support,
providing the optimal position to initiate the next part of the skill; the
vertical jump (Blazevich,
2013).To determine the optimal techniques and the biomechanical principles behind these techniques, there first needs to be a clear understanding of the environment in which the skill is to take place. As discussed previously the jump shot is an open skill and its execution
is influenced by external factors most significantly the position of the
defender. Therefore, the jump-shot is required to be a quick and explosive
movement that allows the attacker to release a shot before the defender can
block. Hence, there are two scenarios in which the preparatory
phase of the jump-shot is influenced these are: receiving the ball and shooting
off the dribble.
When receiving the ball the feet, body and hands
should be prepared and ready to execute the jump-shot as efficiently and
quickly as possible. The feet should be positioned such that they are staggered, with the shooting foot slightly ahead, approximately shoulder width apart,
standing on the balls of the feet, followed by a slight flexion of the knees.
This ensures that the centre of gravity is lowered and maintained within the
base of support, providing stability and balance (Blazevich, 2013). If the feet are too narrow as seen in Figure 1(a) then it is more difficult to maintain a centre of gravity within the
base of support. Conversely, positioning that's significantly wider than shoulder width as seen in
Figure 1(b) impairs the athletes ability to change position and direction quickly.
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Figure. 1 (a) stance too narrow (b) stance too wide. Retrieved from http://www.humankinetics.com/excerpts/excerpts/a-proper-stance-increases-your-shooting-percentage
|
Likewise, having the
shooting foot slightly forward allows
for the foot, shooting arm, and ball to be more closely lined up in a straight
vertical line as seen in Figure 2 this is important as it's known that moving in
a straight line allows for a greater chance to produce highly accurate
movements (Blazevich,
2013).
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Figure 2. Shows straight line position of ball,
feet and arms. Retrieved from:
http://www.humankinetics.com/excerpts/
excerpts/a-proper-stance-increases-your-shooting-percentage
|
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| Figure 3. Stephen Curry producing jump shot off the dribble. Retrieved from https://au.pinterest.com /myawright453/stephan-curry |
In relation to positioning the body for the execution phase off the dribble, the time constraints applied by the nature of basketball play influences the necessity for the attacker to brake as quickly and suddenly as possible to get into a position to execute the shot.
As you can see from Figure 3 Stephen Curry the reigning NBA MVP for the previous two seasons is producing a jump shot off the dribble. The key point of focus is the first two frames on the right, which clearly show how he has planted his feet ahead of his body. This is done in an attempt to instill a braking impulse, as we know that when the foot lands well in front of the body’s centre of mass it produces a large braking force (Blazevich, 2013). This aids the player in reducing forward momentum, allowing them to come to an abrupt stop, and ensures that the body is in a position of stability and balance to commence the execution phase of the skill.
Execution Phase
Movement Phase 1
Newton's First Law - Inertia
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” (Romero, Santiago & Vergara,
2003), also known as Inertia, is important in the vertical jump movement phase.
All objects with a mass have inertia and the larger the mass, the more
difficult it is to change the objects’ inertia (Blazevich, 2010). This applies
to both the vertical jump and the basketball itself. When the shooter is ready
to jump off of the ground, he or she must change their inertia to a vertical
motion (Romero, Santiago & Vergara, 2003). Centre of mass plays an
important role in this resistance change and is evident in Figure 6 As we can see Curry applies
the required force to jump, whilst keeping his center of mass central. This is important because, if whole body rotation occurs an unbalanced landing would
result and effect the execution of the shot (Blazevich, 2010). Inertia can also
be applied to the movement of the ball. The basketball is symmetric and can
spin on any axis, therefore the mass moment of inertia is the center of the
ball (Blazevich, 2010). Once the ball has left the shooters hands, it will
continue to move horizontally through the air (linear velocity) until gravity
pulls it back down (Blazevich, 2010).
Force/Summation of Forces
Force is a
critical contributor of the basketball jump shot. The force used by the shooter to release the ball, and the force generated from the shooters contact with the ground during the initiation of the jumping action, dictate the accuracy and power of the shot . Wuest and Butcher (2009), suggested that: “Body force is produced by the actions of muscles. The
stronger the muscles, the more force the body is capable of producing. However,
the force of the muscle group or groups must be applied in the same direction and
in proper sequence to release the greatest force". To obtain this maximum force, it’s important to combine the forces applied by
different body parts; this is known as the summation of forces (Wuest &
Butcher, 2009). To create optimum power, the shooter must use a summation of
forces starting from their knees and legs and closing at their wrist and
fingers to create the optimum force needed to propel the basketball.
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| Figure 4. demonstrates the summation of forces at work, in a basketball jump shot. Retrieved from: http://bleacherreport.com/articles/403405-the-genius-of-a-ray-allen-jump-shot-from-hero-to-zero |
Figure 4 above is a progressive image of Ray
Allen that demonstrates the summation of force at work. The summation of force
begins in the calves, then moves to the quads, torso, and biceps and into the
wrist, before eventually being applied to the ball through the fingertips (Wuest & Butcher, 2009). A key technical
aspect to note is the position of the knee joint when starting the summation of
force. The flexion of the knee joint at the initiation of the summation of
force increases the range of motion of the knee. This provides more time to
produce force and creates a greater velocity. Additionally, the shooter must
still create adequate force to get off the ground. Newton’s Third Law is
relevant in this movement phase, it states “For every action, there is an equal
and opposite reaction” (Blazevich, 2010). This is significant, as it allows us
to calculate the amount of force the shooter is required to produce to get off of the
ground. Force is calculated using the formula: Force = (mass) x (acceleration)
(Blazevich, 2010).
Kinetic Chain
The
basketball jump shot involves a combination of both push and throw like
movement patterns. In this movement phase the push-like movement pattern is
most evident when the feet, ankle, knee and hip joints in the kinetic chain move simultaneously, generating high cumulative force and work together to
create the jump. These joints extend to perform straight-line movements, and if
the jump is executed correctly the overall accuracy of the shot will be
increased (Knudson, 2007).
Movement Phase 2
Potential Energy
Potential
energy is the energy connected to body position and is relevant in the second
movement phase of the basketball jump shot. When the shooter is stationary they
have the potential to gain kinetic energy (Winter, 2009). Potential energy refers
to movement: distance and displacement. Decreasing the distance between the
ball and the shooters body in the ready to shoot position (ball in fingertips,
elbow in the L shape) will maximize the potential energy going into the release
(Knudson, 2007). Therefore a player who holds the
ball further away from their torso, is likely to have less potential energy
than that of a player who holds it close, prior to release (Knudson, 2007).
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| Figure 5. Shows the potential energy that can be gained from holding the ball closer to the torso upon delivery. Retrieved from: http://www.espn.com.au/nba/story/_/ id/10703246/golden-state-warriors-stephen-curry-rein venting-shooting-espn-magazine |
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Figure 6. Demonstrates that holding the ball away from the torso
upon
delivery, will produce minimal potential energy. Retrieved from:
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Figure 5 shows an image of Stephen Curry in the
delivery phase of the basketball jump shot. The angle between his bicep and
forearm is much smaller than that of the angle seen in Emmanuel Mudiay’s arm in
Figure 6. Disregarding other external
factors that could influence each jump shot, Figure 5 is likely to have more potential energy and overall result
in a successful shot, as apposed to Figure
6. Stephen Curry who was not only the MVP but one of the most efficient
shooters from beyond the arc in the 2015/16 season, utilizing the jump-shot,
with a 55% success rate. This is compared to Emmanuel Mudiay who only successfully scores 27.6% of
the shots attempted beyond the arc (nba.com, 2016). Whilst there are other
influencing factors that contribute to these statistics, potential energy could
have played a considerable role in Stephen Curry's efficiency rating (nba.com,
2016).
Angle of Projection
The angle of
projection is a crucial factor that influences the projectile range (Knudson,
2007). Objects can be projected at angles between 0 and 90 degrees, these objects will
travel both vertically and horizontally. An object projected at an angle of 0 degrees will travel horizontally but remain on the surface it was projected (will not
become airborne). If an object is released at a projection angle of 45 degrees, the object
will have an equal magnitude of vertical and horizontal velocity and its range
will be maximized (Knudson, 2007). The exact release angle of the jump shot is
controversial, as the player’s position on the court, their height, the height
of release and their shoulder and trunk angle all affect the angle of release
(Hudson, 1982). Therefore, research suggests that release angles between
45-55 degrees will significantly increase the chance of a successful goal
(Hudson, 1982). Optimal performance of the technique requires a higher
angle of release to increase the trajectory of the ball, as a lower release
point and a lower angle of projection would result in the ball reflecting off
of the ring.
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Figure. 7 Illustrates the trajectory path
of a basketball released at a 45 degree
angle (Hudson, J.L., 1982
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Projection Speed
The
distance the ball travels, both horizontally and vertically, is influenced by
its projection speed (Blazevich, 2010). There are two projectiles in the
basketball jump shot; the ball and the player in the jump motion. The projectile speed of the ball needs to be both horizontal and vertical, whilst the player
needs to be only moving vertically. The shooter should aim to release the ball
at the very peak of their jump for optimum performance and success rate. At
this point there is minimal forward, upward and downward speed, which otherwise
could affect the shooters judgment of force to exert. The vertical velocity of
the shooter’s body adds to the vertical velocity of the ball (Projectile Motion, 2013). The ideal angle of release
for a jump shot attempted from mid-range (inside the 3 point line) is 52
degrees. This provides the ball with minimum speeds that allows for a clean,
successful shot (Elliott & White, 1989). See Figure. 7.
Movement Phase 3
Kinetic Chain
During the
final stages of execution, the throwing motion is the dominant movement
pattern. This occurs when the shoulder, elbow and wrist joints in
the kinetic chain extend sequentially, one after another (Knudson, 2007). The shoulder begins to extend,
while the elbow is still flexing during the lead-up to release phase. In the
later stages of release, the extension velocity of the hands and fingers
increase greatly which results in high ball release velocity (Knudson, 2007). See Figure 8.
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| Figure. 8 Demonstrates a progression image of Steph Curry performing a jump shot. Retrieved from: http://www.espn.com.au/nba/story/_/id/10703246/golden-state-warriors-stephen-curry-reinventing-shooting-espn-magazine |
Newtons Second Law of Motion
Newton’s
Second Law of motion comes into play during this movement and directly applies
to this movement phase of release; “the acceleration of an object as produced
by a net force is directly proportional to the magnitude of the net force, in
the same direction as the net force and inversely proportional to the mass of
the object” (Romero, Santiago & Vergara, 2003). To change an object’s state
of motion, a force needs to be applied, this can be observed in the later
progressions of Figure 8, where Curry applies the required force to the ball to accelerate it out of his hands. The
ball steadily gains momentum and is forced in the direction of the goal
(Romero, Santiago & Vergara, 2003).
Newton’s Third Law of Motion
Newton’s
Third Law is also evident during this movement phase. As the ball gains
momentum towards the basket, it acts back on the shooter, however because the
shooter is going to carry a greater mass than the ball, he or she will
not take off with an equal speed in the opposite direction (Knudson, 2007).
Therefore will not accelerate backwards, during the balls forward acceleration
(Romero, Santiago & Vergara, 2003). This is important as it allows the
athlete in the release of the shot to remain in an upright vertical position,
which improves the likelihood of the athlete landing in a balanced and stable
position, ready to make the next move.
Movement Phase 4
Ball Rotation
In addition to optimum projection angle and
projection speed, ball rotation is also a crucial component of the release
(Hamilton & Reinschmidt, 1997). Backspin applied to the ball during the jump
shot serves to decrease the horizontal velocity of the ball. Hence, if the ball strikes the rim or the backboard it will fall downwards(Hamilton
& Reinschmidt, 1997). The wrist action and angle of the forearm are the two
critical techniques the shooter should focus on to generate backspin (Lam,
Maxwell & Masters, 2009). When the ball is held with the correct grip and the
forearm aligned vertically, the shooter can apply the required backspin on the
ball, this is evident in Figure 6. The
flexion of the wrist occurs quickly at the end of the shot, upon release.
Studies suggest that skilled shooters often release the ball with their wrist
slightly hyper-extended, reamining in this state until the ball has completely
left the hands for the follow through (Knudson, 2007). This can be seen in Figure 5 above.
Follow Through Phase
The follow through phase is the last phase of
the jump shot and begins with how the player lands from the jump. It is
significantly important that the player lands back in the balanced stance that
he or she took off from; this prepares them for the next action they need to
execute (Knudson, 1993). Like the role of inertia in the take-off of the
execution phase, it’s significantly relevant to the landing. After the shooter
leaves the ground, they will initially move upwards and only begin to descend
when acted on by the force of gravity, which will take place after the ball has
left their hands (Ganley, 2013). An important factor in the technique of landing
is attempting to flex the lower limbs before landing, and land on the balls of
the feet (Bober,
Rutkowska-Kucharska, & Szpala, 2003). The critical reason for instilling flexion at
the ankle and knee joints is to reduce the amount of force exerted on the legs
at landing. Likewise, the earlier the heel is contacted with the ground the
larger the impact force (Bober et al.,
2003).
As you can see in Figure 9 Ray Allen has clear flexion in the lower limbs, as
well as, landing on the ball of his feet. Ensuring the athlete makes a soft
landing is vital to reduce excessive local load on the lower limbs and
preventing potential injury (Struzik,
Pietraszewski, & Zawadzki, 2014). To ensure the optimal technique of a skill,
there must be sustainability in the movement pattern, otherwise the long-term
success of the athlete may be affected.
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Figure. 9 Ray Allen landing from a jump-shot. Retrieved from: Retrieved from:
http://bleacherreport.com/articles/403405-the-genius-of-a-ray-allen-jump-shot-from-hero-to-zero |
The follow
through of the arm and wrist is dependent on the movement of the arm and elbow
position during the previous phases. The shooter should aim to follow through
with their wrist, so that it finishes fully extended and fingers pointed
downward. This is evident in Figure 10. Ensuring
that the athlete maintains the extension of the wrist, will improve the probability
that the athlete has successfully instilled the correct ball rotation during
the execution phase.
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| Figure. 10 Stephen Curry demonstrates the flexion of the wrist after ball execution. Retrieved from: http://www.espn.com.au/nba/story/_/id/10703246/golden-state-warriors-stephen-curry-reinventing-shooting-espn-magazine |
How else can we use this information?
In deconstructing the optimal technique in the jump shot
and the biomechanical principles that justify it, similarities can be found
within other sports which utilize similar movements to capitalize on these biomechanical principles. Key similarities between multiple sports can be observed in the utilization of push-like patterns in the legs followed by a throw-like
pattern in the arms. For example, during the tennis serve , players utilize a
push-like pattern in the lower limbs to launch themselves into the air, providing
vertical velocity, this is then followed by a sequential extension of the
racquet arm to instill a throw-like pattern and hit the ball (Blazevich, 2013). Likewise, you
can see a similar utilization of push and throw like patterns in other open
kinetic chain skills such as, the javelin throw, netball chest pass and even
bowling in cricket.
Another key technique within the basketball jump-shot
that is utilized in other sports is quick flexion of the wrists as the ball is
released, in an attempt to apply a backwards rotation on the ball. We can see
comparable techniques used in bowling in cricket. The bowler at the final
release of the ball will instill rapid flexion of the release hand to produce a
backward rotation (Blazevich, 2013). Likewise, the
same concept is utilized in a shot for goal in netball.
Relative height of projection is another biomechanical
principle utilized in the jump-shot that can be observed in a variety of other
sports. Skills that require getting the object over a net such as tennis and
volleyball. In relation to the serve of these two sports, the skill requires a
vertical jump before the object is released. This decreases the angle required
to get the ball up and over the net, reducing the need for vertical velocity,
and allowing for greater force to be concentrated on producing horizontal
velocity (Blazevich, 2013).
Another key point that can be determined through considering the optimal technique of the jump-shot and the corresponding biomechanical
principles, is the influence these answers can have on the required optimal
physiological factors that will enhance the techniques suggested. For example,
we know from Newton’s second law that to accelerate ourselves into the air we
need to minimize mass and increase the force that we can apply(Blazevich, 2013). Therefore, in
the endeavor to produce the largest vertical jump possible for optimal
performance in the jump-shot, the athletes should attempt to increase power
while maintaining a relatively low body weight. Similarly, as discussed before
in relation to injury, if the mass of the athlete is decreased a reduction of the force of the lower limbs would be applied when landing.
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