A basketball shot or field goal is often referred to as a ‘jump shot’. The jump shot consists of a player rising into the air to shoot the ball over the defending opponent and towards the basket. The jump shot is distinguished as the most important scoring method in basketball, catering for 41% of total scores in the Spanish Basketball League (Rojas, Cepero, Ona, and Gutierrez, 2000). Gel’s (2014) summarises that the jump shot is the most commonly used shot in current basketball because it can be used to score ‘on the move, and in traffic, by jumping and extending your shot over the defender’. Knudson (1993) also explains that to have an accurate jump shot, coaching literature regularly states that a stable base and vertical jump are recommended, but why?
Using bio-mechanical principles the following research and analysis aims to determine why a jump is included when shooting the basketball. “Biomechanics, as a subdiscipline of physical education, exercise science, and sport, focuses on the application of the scientific principles of mechanics to understand movements and actions of human bodies and sport implements” (Wuest & Fisette, 2012, p. 184). The aim of a jump shot is to score so the key bio-mechanical principles that will guide the following analysis will be focused on the accuracy, direction and consistency of the jump shot.
In order to find a solution to our question, some guiding questions have been developed that build the foundation for the research.
- Does the jump increase the accuracy of the shot?
- Does jumping increase the shooters chance to develop an efficient shooting method with consistent accuracy?
- How does the jumping aspect affect the ball’s trajectory?
The bio-mechanical principles listed below will be focused on throughout this discussion:
- Force
- Newton’s Laws
- Work
- Power
- Projectile Motion
FIG. 1 – Summation of force through the execution of a jump shot.
Force is the product of mass and acceleration (Blazevich, 2010). In a basketball shot a force has to be placed on the ball for it to travel towards the hoop, but the person shooting the ball also has to apply a force to the ground that elevates them into the air, a jump. The force that is placed on the ground transfers itself through the body into the arms and onto the ball, this summation of forces is shown in FIG. 1 as the player elevates into the air to shoot the ball. Miller and Bartlett (1996) found that the ball release speed of players increased when the distance from the basket was greater. Therefore the amount of force applied to the ball will vary depending on the distance of the shooter from the basket. Jumping when shooting the ball will also influence the amounts of force applied during the movement. In FIG. 2 we can see two shots as they initiate in the force production stage. The shot that is without a jump requires a greater amount of force to be applied which results in there being a greater torque that propels the body upwards to shoot the ball.
FIG. 2 – Initiation of force production stages of two different basketball shots
We know that the jump shot is commonly used because of its effectiveness at scoring when the player who is shooting the ball is being defended, but without the necessary application of force to elevate vertically, the shooter cannot effectively execute a jump shot. “How high someone can jump depends on the force he uses to push on the floor when he jumps, which in turn depends on the strength and power of the muscles of the legs. The harder and more powerfully he pushes, the higher he goes and the longer he stays in the air” (Top End Sports, 2013).
With an amateur basketball player with relatively low levels of experience a study was performed to record the accuracies of the jump shot and the set standing shot. Shots of each method were taken from the same seven different angles and distances around the basket (FIG. 3).
The findings from this study showed that for this individual player, the attempts that were performed as jump shots were far more consistent from the greater distances. The movements of the arms during the set shots were more erratic as the individual looked for greater force exertion which could have contributed to the less accurate attempts. A variable that needs to be taken into account is that a player with greater upper body strength will be able to use that strength to transfer force into the ball more efficiently than a player with lesser upper body strength.
Work and power are relevant for the jump shot as they can be used to determine the efficiency of movements, and the player with the more efficient movements will be able to perform the skill repeatedly at a higher level for a longer period of time.
Work can be summarised as the amount of force being applied over a certain distance (Blazevich, 2010). In FIG. 2 we can see that with a jump in the shot execution the distance that the legs have to straighten and apply a force to elevate themselves is smaller compared to the standing release, therefore executing a jump shot requires less work output.
Power is the amount of work performed over any given time (Blazevich, 2010). If a player continues to apply large amount of work forces repeatedly, for example shooting in a basketball game, then they will most likely fatigue faster than a player who uses shorter quantities of force. Therefore the player with the greater power can apply large amounts of working forces for longer periods of time.
To create efficiency within the work and power of the jump shot, basketball players must be able to increase their energy output compared to their energy input (Blazevich, 2010). In other words, the energy that is exceeded must increase relative to the energy it takes to perform the task.
The force that is applied on the ball and the constant force that gravity applies are dominant features in a game of basketball. These features are regularly influencing and manipulating the gameplay in some form. Even so, these forces must counteract each other in order for the ball to move around the court. ‘A player must be aware that simply accelerating the ball directly at the basket will not work, the ball will end up way below the basket when it arrives’ (Simonetti, 1994). This means the player must aim higher than the basket for gravity to take its effect on the ball and put in through the hoop. But how high do we send the ball?
Projectile motion is the motion of an object that has been projected at an angle into the air (Blazevich, 2010). It is obvious that the range and velocity of the projection will vary for a jump shot depending on where on the court the shot is taken from. The two aspects that have the most relevance for accuracy of the jump shot are: the angle of projection and the relative height of projection.
The angle of projection will determine the trajectory the ball takes. In basketball ‘the optimal trajectory depends on the shooter (Hamilton and Reinschmidt, 1997, p. 494). This is because each shooter will be of different height, and therefore have different release points.
The angles below are the optimal angle of projection for the specific height of the player for a standard free throw attempt (Fisher Sharp Shooters, 2013).
- 5’4″ player should launch the ball at a 52.2 degree angle
- 5’8″ player should launch the ball at a 51.5 degree angle
- 6’0″ player should launch the ball at a 50.8 degree angle
- 6’4″ player should launch the ball at a 50.1 degree angle
- 6’8″ player should launch the ball at a 49.4 degree angle
- 7’0″ player should launch the ball at a 48.7 degree angle
If the arc of the ball is higher, the angle of which the ball enters the hoop will have a greater target (FIG. 4).
Hamilton and Reinschmidt (1997) state that the existence of human motor-control limitations means that there is no combination of angle and velocity available that can be repeated exactly by a shooter. This means that shooting the ball is completely variable and the angle of release is determined by the shooter making all the necessary movements and calculations to get as close to the optimal release as possible.
‘The relative height of projection is the vertical distance between the projection point of an object and the point at which it lands’ (Blazevich, 2010). As seen in FIG. 5 the jump shot technique has a higher release point therefore, a different angle of projection and optimal angle will be required for the shot to have the best chance to go in the goal. We also see that because of the extra force production that takes place in the arms during the set shot, the release point is further in front of the shooter once again altering the optimal trajectory.
FIG. 5 – Shooting release points
This information will also be variable in regards to the height of the shooter and their release point. If the release point is higher (as seen above due to the varying heights of players) the jump shot technique allows players to shoot the ball at a lower angle. The higher the release point, the lower the angle will need to be.
THE ANSWER
So why do basketball players jump when shooting the ball? The jump allows the player to generate forces that start from their feet to their wrist as they shoot the ball, making it a whole body action. The set shot that does not use a jumping release requires players to generate a larger amount of force through the arms and generate more torque from their legs. Instead of erratic, jerky movements that can happen when trying to apply enough force onto the ball without an appropriate summation of forces to maintain enough distance, the jumping motion also allows shooters to have a fluid chain of movements that allow for greater ball control as the arms move at a steady pace and can release the ball softly at the top of the jump.
The jumping action is much more efficient as it requires a lower amount of torque to be applied in the legs and the summation of forces is equal across the body, therefore the amount of work and power output that is produced is spread across the entire body allowing the player to maintain effective movements for longer time periods before fatiguing.
HOW ELSE WE CAN USE THIS INFORMATION
This information can be used to determine flaws in jump shooting. It can also help in determining whether or not the shooting motion of an individual is being executed efficiently. For other sports that involve jumping or projection of objects these findings may also be helpful for determining efficient movements and optimal trajectories.
Further research may be needed on the in game variables that may affect the player’s shot such as defenders, concentration, perceived pressures and the situations that can only be found in competitive game scenarios.
References
Blazevich, A. (2010). Sports Biomechanics The Basics: Optimising Human Performance. (2nd Ed.) London: A&C Black Publishers.
Fisher Sharp Shooters. (2013). Secrets of Shooting. Retrieved from http://www.secretsofshooting.com/the-physics-of-shooting/
Gels, J. (2014). Basketball Jump Shot. Retrieved from http://www.coachesclipboard.net/JumpShot.html
Hamilton, G. R. & Reinschmidt, C. (1997). Optimal trajectory for the basketball free throw. Journal of Sports Sciences, 15(5), pp. 491-504.
Knudson, D. (1993). Biomechanics of the basketball jump shot - six key teaching points. The Journal of Physical Education, Recreation & Dance, 64(2), 67-77.
Miller, S. & Bartlett, R. (1996). The relationship between basketball shooting kinematics, distance and playing position. Journal of Sports Sciences, 14(3), pp. 243-253.
Rojas, F. J., Cepero, M., Ona, A. & Gutierrez, M. (2000). Kinematic adjustments in the basketball jump shot against an opponent. Ergonomics, 43(10), pp. 1651-1660.
Simonetti, J. (1994). What components of Newtons laws of motion are most important to shooting and making a basket? Retrieved from http://www.phys.vt.edu/~jhs/faq/physics.html
Top End Sports. (2013). Basketball Physics. Retrieved from http://www.topendsports.com/sport/basketball/physics.htm
Wuest, D. A. & Fisette, J. L. (2012). Foundations of Physical Education, Exercise science, and Sport. (17th Ed.). New York, NY: McGraw-Hill.
