Jump shot definition: a shot at the basket
made by a player releasing the ball at the highest point of a leap (Collins
English Dictionary, 2003).
The Answer
Force
There are many different biomechanical principals that
contribute to the effectiveness of a jump shot in terms of its accuracy and
power. One of these is force. Force can be looked at in a number of different
ways when relating to a jump shot. For example, there is the production of
force that the shooter uses to release the ball, and then there is also the application
of force to the ground in order for the shooter to start the jumping motion.
According to Wuest and Butcher (2009) “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 realise
the greatest force.” (p. 237)
This leads to an important biomechanical principal, which is
the summation of forces. In order to impart the most power on the basketball
the shooter must use a summation of forces starting from their legs and concluding
right at their fingertips as they release the ball. As a result of an increase
in power being added to each muscle group from the one before it the wrist and
fingers will be able to push the ball a lot further than they would have been
able to if they were the only muscle groups involved.
Image 1, Source:
Unknown Author i
Image 1 shows the summation of force, which begins in the
calves and moves through the quads, trunk, shoulder, bicep, tricep, and wrist
before being applied to the ball by the fingers.
The jump shot is defined as a shot where the ball is
released at the highest point of the jump. In order for a player to leave the
ground and take their shot they must apply sufficient force to the ground to
create upward reaction force. Newton’s third law states that “ For every
action, there is an equal and opposite reaction” (Blazevich, 2012, p. 45). Force
is measured in newtons and can be calculated by the formula F (force)=m (mass)
a (acceleration). Acceleration on earth is 9.81 metres per second (or
approximately 10) due to the effect of gravity.
So for someone with a mass of 80kg the equation to calculate
their weight (mass is the amount of matter in an object, weight is the effect
of gravity on matter, it is measured in newtons) looks like this.
F = 80 x 10m.s
F = 800 N
So in order to get off the ground an 80kg person must direct
more than 800 N (typically it will require a lot more to do a significant
enough jump to perform a jump shot) of force into the ground in order to create
a reaction force that will send them into the air. (Blazevich, 2012, p. 45)
Wuest and
Butcher (2009) state that “ Force from the legs must be applied to the ground
such that the upward reaction force from the ground is directed through the
centre of mass of the body” (p. 238).
It is important for the shooter to have their feet shoulder
width apart as they start to jump so that their centre of mass stays along the
midline of their body. If they are leaning to either side, or to the front or
back, then their body will travel in that direction as they leave the ground
and they will not jump as high. Jumping straight up vertically also helps with
the accuracy of the shot as the body stays more balanced in the air and the
shooter will be able to keep their eyes fixed on the ring.
Image 2
illustrates the principals of force being created from the legs and also upward
reaction force. It also shows the importance of keeping the centre of mass
along the midline of the body. The red arrows show the direction that force is
applied to the ground from the legs and the green arrows show the direction of
the upward reaction force that is created by the initial downward force. A
force plate attached to a wall can measure the leg press force output.
Image 2, Source: Unknown Author II
Levers
“Levers enable one to gain a
mechanical advantage by producing either strength or range of motion and speed”
(Wuest & Butcher, 2009, p. 236). When shooting a basketball using the
correct technique the arm with which the ball is shot will act as a lever and
help increase power in the shot. All levers consist of three things:
·
- A fulcrum or axis around which the lever rotates
- · A force arm, which is measured by the distance between the fulcrum and the place where the force is applied
- · A resistance arm, which is measured by the distance between the fulcrum and the place where resistance is applied (Wuest & Butcher, 2009)
There are three different types of
levers in the body, first class levers, second class levers and third class
levers. The jump shot uses two third class levers. The third class lever shown
in Image 3 is used to gain power in
the jump shot and has its fulcrum in the elbow joint, the effort where the
tricep muscle connects to the forearm and the load where the ball is held in
the hand.
Image 3, Source;
Unknown Author II
This lever works as the tricep muscle moves from being in an
eccentric contraction as shown in image 3 to a concentric contraction once the
arm has straightened out as the ball is released. The tricep actually connects
to the forearm via a tendon just above the elbow joint, which is what makes
this a third class lever and not a first class lever.
The second type of lever used in this technique has more to
do with the accuracy of the shot. It is another third class lever that is
similar to the first one but has its fulcrum in the wrist, its effort where the
tendon from the forearm connects to the hand and its load where the ball is
held in the hand.
Image 4, Source:
Unknown Author II
This lever is what helps to guide the ball off the middle
and index fingers as the shot is completed. As the wrist muscles and tendons go
from eccentric contraction to concentric contraction they pull the wrist
upwards and make it follow through linear to where the forearm is facing.
Haefner (2008) discusses the importance of effectively using
this lever in jump shooting technique.
·
- Your elbow and wrist should extend in a straight line to the basket.
- · Your shooting hand should extend in a straight line to the rim.
- · Hand position on delivery is very important. The ball should come off the hand with perfect symmetrical backspin.”
Image 5, Source: Breakthrough Basketball
Image 5 illustrates the importance of the third class lever in the
wrist, which enables the shooter to release the ball and have it travel linear
to where the forearm and wrist were facing.
Projection Angle
The power required for a particular jump shot and also the accuracy of
the shot are largely affected by the projection angle/release angle.
“The maximum range of a
projectile is determined partly by its angle of projection. When the angle is
greater, the object attains a greater vertical height but lesser range. When
the angle of projection is too small the object doesn’t have sufficient
vertical velocity to attain significant range.” (Blazevich, 2012, p. 26)
Okazaki and Rodacki state that “the release angle and entry angle of the
basketball into the hoop are directly related to each other” (2012, p. 321).
Therefore the angle of projection has significant importance on the accuracy of
a jump shot.
Figure 1,Source: Okazaki & Rodacki
As can be seen in Figure 1, when
the entry angle decreases so does the target size (indicated by T). The optimum
angle of release for a mid to long range jump shot is between 50-70 degrees.
When in close to the basket the shooter will be able to release the ball at a
higher angle which requires more power and gives the ball a greater entry
angle. However, when they move out further from the basket the angle of release
will decrease because the power required for a high angle of release is too
much to perform with control. The height of release also has a big influence on
the angle and power required in the release. For the example shown in Figure 2 we are assuming that the angle
of release is 7ft from the ground.
Figure 2, Source: Advantage Basketball Camps
Figure 2 shows how when shooting a
jump shot from further away the shooter will have to release the ball at less
of an angle than they would have in close even though we know from Figure 1 that this decreases the target
size of the ring. This is done because as Figure
2 shows, if the shooter was to maintain the same 70-degree angle of release
when further out as was used in close, the arc of the shot would be a lot
greater. Whilst this greater arc would allow for a bigger target zone at the
ring it requires a lot more power and in the process of producing that extra
power accuracy is likely to be lost.
How else can we use this information?
The topic question for this
blog revolved around assessing what biomechanical principals are used in a jump
shot to gain accuracy and power. The three principals discussed above in the answer
are ones that can be applied to many different sports.
For example, the notion of
force being used in two ways while performing a jump shot may be helpful to
someone who is playing a sport that requires vertical leaps or some sort of
throw. A high jumper might take this information and measure the amount of
force that their leg press can produce as well as the weight of the body. They
can then train to improve this number knowing that it will lead to an improved
vertical leap. Or similarly, a shot putter may use this information to better
understand that they will be able to maximize the amount of force through their
arm by using a summation of forces in the right order starting from their legs.
Levers are also beneficial
to basketballers and other athletes who may have read this blog. The answer
above concludes that the jump shot uses two different levers, which both help
in gaining power, and accuracy. This information could be applied to other
sports by isolating where levers are used for a particular skill, and then
working to increase the strength of the muscles that provide the effort for
that lever.
The projection angle and
trajectory of an object (in this case the basketball) is something that is
important in a whole different range of sports. Understanding the importance of
the angle of release may help a javelin thrower to increase the distance of
their throw even without gaining any strength in their arm. Similarly if a
netball shooter were to view this blog they would be able to understand that
when in close to the basket it is beneficial for them to shoot a high arcing
shot, from a high angle of release, in order to give themselves the biggest
target zone.
Perhaps the most important
way that the information presented here can be used, is to encourage others who
seek to perform a biomechanical analysis of a skill to use photographic and
video footage to assist them. Taking photos of a skill in action or watching
the skill played back in slow motion allows you to analyze the biomechanical
principals that it involves better than you could by just watching it
live.
A good way for an athlete
to use this information to improve their jump shot would be to apply the
principals learnt here in a 5 step biomechanical intervention. According to
Blazevich (2012, p. 210) “A detailed plan is very important in order that the
most influential biomechanical flaws are noticed and corrected.”
Word Count, 2,065
References
Blazevich, A., J. (2012). Sports Biomechanics the
Basics: Optimising Human Performance. Bedford Square, London: A&C Black
Publishers Ltd
Collins English Dictionary. (2003). The Free Dictionary: jump shot. Retrieved from http://www.thefreedictionary.com/jump+shot
Figure 1, Okazaki, V. & Rodacki, A. (2012). Schematic representation of the vertical
virtual target. Retrieved from http://www.jssm.org/vol11/n2/5/v11n2-5pdf.pdf
Figure 2, Advantage Basketball Camps, Advantage Basketball Camps Shooting camp(image). Retrieved from http://www.advantagebasketball.com/shootingcamp.htm
Haefner, J. (2008). Proper
Basketball Shooting Technique, Fundamentals, and Form. Retrieved from http://www.breakthroughbasketball.com/fundamentals/shooting-technique.html
Image 1, Unknown Author I. Bleed Basketball (image). Retrieved from http://ibleedbasketball.com/category/developing-your-game/
Image 2, 3, 4, Unknown Author II. Stick This Graphics (image). Retrieved from http://www.stickthisgraphics.com/Jump-Shot-Silhouette-Decal-Sticker-BSKT17.htm
Image 5, Breakthrough Basketball. Breakthrough Basketball (image). Retrieved from http://www.breakthroughbasketball.com/fundamentals/shooting-technique.html
Okazaki, V. H. A., & Rodacki, A. L. F. (2012). Increased
distance of shooting on basketball jump shot. Journal of Sports Science and Medicine, 11, 231-237
Wuest, D. A., Butcher, C. A. (2009). Foundations of Physical Education, Exercise science, and Sport. New
York, NY: McGraw-Hill
