Major Question:

What are the biomechanical principles involved in the optimal basketball jump shot?

Basketball is a sport that was invented in 1891 by Dr James Naismith at the Y.M.C.A College, in Springfield Massachusetts (Basketball Victoria, 2015). Forty years after the discovery of the game, the basketball jump shot was developed, which is now considered as the primary skill used in the game of basketball. Historians have defined a jump shot as when a player vertically jumps and releases the ball at the top of their jump (Pennington, 2011). As it is known as the optimal preference for scoring, over 70% of scores during a game come from the use of a jump shot. The sport of basketball comprises of a variety of biomechanical elements and it is important to consider these when shooting an accurate jump shot. In this blog, the biomechanical principles and movements involved in an optimal jump shot will be thoroughly analyzed. Followed by an experiment conducted displaying several biomechanical principles to enhance the success of a basketball jump shot.

The Answer:

Optimal Technique:

Positioning and accuracy

To generate a successful basketball jump shot, there are a number of sequences used to produce an optimal technique. Firstly, the shooter is encouraged to stand with their feet shoulder width apart to maintain balance and ensure their centre of mass is inline with the basket. To further enhance shooting accuracy, the athletes shoulder, elbow and hip are in line with one another. The ball sits in the palm of the athlete’s hand with the forearm in line at eye level to produce greater accuracy in the shot as the forearm does not block the athlete’s vision (Miller & Bartlett, 1996). The shoulder then lifts the ball by flexing to an angle between 90° and 135°.  It is recommended that the shooting arm be lifted very close to a fully extended vertical position to release the ball. The movement of the arm, forearm and hand, followed by the alignment of the shoulder, elbow and wrist simultaneously work together to produce a single plane of motion. The extension of the ankle, knee and hip joints also occurs simultaneously as the ball is elevated to perform the jumping motion (Okazaki, 2014). An elevated release point reduces the distance from the basket therefore increasing the accuracy of a shot going in. The point of release should be just before the apex of the jump, driving the momentum of the legs through the arm, wrist and follow through motion (Okazaki, 2014).   

Ball Rotation / Backspin

The perfect biomechanical jump shot applies a backspin motion or ball rotation to create a shot that may rebound into the basket. Backspin on the flight of the ball ultimately decreases the horizontal velocity of the ball therefore causing it to deflect downwards if it strikes the backboard. In figure 1, the image demonstrates that the greater the spin on the ball as it hits the basket, the more energy is transferred by friction (Kentridge, 2003). Backspin on the ball creates a soft, accurate shot and can decrease the chances of the ball hitting hard against the backboard or the ring (Knudson, 1993). 

Figure 1. Ball spin influenced by friction

It is also evident that the rotation of the ball can be created with the fingertip control, wrist action and a follow through motion. Sports science (2005) recommends the use of players “flipping” their fingers under the ball to generate the spin. Using an appropriate grip and having the forearm aligned vertically, allows for the shooter to apply backspin on the ball (Knudson, 1993). Wrist extension emphasizes the motion of backspin and as the ball is being released, the wrist is slightly hyper-extended. Decreased wrist flexion during the follow through phase, may influence the wrist velocity and result in a lower ball release and ball rotation (Okazaki, 2015). Therefore, vigorous wrist flexion at the peak of the release creates a follow through motion, allowing the overall backspin on the ball to generate a favorable spin into the basket.      

Kinetic Chain:

A basketball jump shot incorporates movement pattern within the kinetic chain, known as throw-like and push-like and can be adopted into an athletes shooting technique. A push-like movement pattern extends all joints in the kinetic chain simultaneously in a single movement. A throw-like movement pattern differs, as the joints of the kinetic chain extend sequentially, one after another (Blazevich, 2013). A less skilled athlete generally begins with a push-like action and progresses to a throw-like.

Throw-like

The throw-like movement pattern is commonly used during the sequential extension of joints to execute the throwing action of the shot (Okazaki, 2014). Shoulder and hip rotation, elbow and wrist acceleration and finger and ball acceleration are the movement patterns consistently used to perform a jump shot. As an athlete takes a jump shot and uses a throw-like motion, altogether these joints create momentum through large muscle forces.  Acceleration of these movement patterns in the kinetic chain generates power for the shot to reach the distance of the basket (Blazevich, 2013). As the athlete is jumping in the air prior to releasing the ball, kinetic throw-like energy is transferred to the arms and hands to produce force and ball acceleration (Struzik, 2014). 

Push-like

A push-like movement pattern is commonly used in the preparation phase of executing a jump shot. In the jumping stage of the shot, all joints within the legs, hips, knees and ankles of the kinetic chain, extend simultaneously in a single movement, therefore producing a higher amount of force. As the athlete jumps vertically off the ground, this results in higher overall force, which transfers through the body of the kinetic chain consequently resulting in an accurate shot (Blazevich, 2013). As the athlete is moving forward towards the basket, the body travels at a fast horizontal velocity, therefore produces greater momentum for a higher and accelerated jump. The athlete consequently will generate enough force to elevate their body off the ground (Alexander, 2010).

Projectile Angle & Motion:

Projectile angle

The ball projectile angle/release angle into the hoop is considered to be one of the main factors in completing a successful biomechanical jump shot. An accurate jump shot can vary in its release angle due to an individual athletes height, movement patterns, and the presence of a defender (Blazevich, 2013). A perpendicular projectile angle is considered to provide a larger area for the ball to fall through the width of the basket (Okazaki, 2014). An optimum angle of release for a mid to long-range jump shot is between 50°-70°. As seen in figure 2, when the shooter is performing a long-range jump shot, the angle of release decreases due to the amount of power required to control a high projectile angle.

Figure 2. Long-range and short range projectile angle 

Release height

It is evident that maximizing the height of release of the ball increases the accuracy of the shot and minimizes error of the shot (Knudson, 1993). Consequently, the higher the projectile arc of the basketball, the increased chance of an accurate shot being executed. However, if the ball is propelled too high in the air, more energy is required to produce the shot, therefore decreasing the level of accuracy (Fontanella, 2006). Consistently practicing a maximized release height at training will allow the athletes to shoot accurately under the pressure of a defender and various ranges (positions) on the court (Struzik, 2014).

Release time

The time of the release at the peak of the jump is considered to increase the overall height of release. On the other hand, there are external influences that affect how fast the ball in released from an athlete’s hand. An athlete who releases the ball at a quicker pace generally does this in the presence of a defender. A quicker release time gives the defender less time to block the shot therefore creating further distance between the shooter and the defender, creating a more accurate shot (Knudson, 1993).  

Vertical and Horizontal displacement:

Vertical and horizontal angles range between 0° and 90° affecting the overall accuracy of the shot. “The lower the release height or the greater the release angle, the greater the vertical displacement of the ball” (Okazaki, 2014).  

Figure 3 demonstrates the level of accuracy when a ball enters the ring at a vertical displacement compared to a horizontal displacement. Entering at a vertical angle is considered to be the more effective approach to maximize success when shooting. “Squaring up” towards the basket generates a stable base of support, and minimizes horizontal motion of the body to allow the athlete to produce an accurate shot (Knudson, 1993). On the other hand, a shot performed at a greater distance does require greater horizontal velocity for the ball to reach the basket.

Figure 3. Vertical and horizontal displacement

Newton’s first law:

Newton’s first law states, “An object will remain at rest or continue to move with constant velocity as long as the net force equals zero” (Blazevich, 2013).

This first law is also referred to as the law of inertia; inertia is described as an object’s tendency to resist any change in its present state of motion, either moving or stationary (Blazevich, 2013). So the larger the mass of an object, the more inertia it has and the harder it is to change that object’s state of motion - inertia (I) is proportional to mass (m) (Benjamin, 2014; Verial, n.d).

In basketball, before the player has released the ball during a jump shot they must first adjust their inertia and change their path of motion from a horizontal plane to vertical to be able to move upwards. To stop, change their direction and accelerated their path of motion upwards they need to apply internal and external forces by using their muscles and footwork (Benjamin, 2014; Verial, n.d). Once they have left the ground the force of gravity will be present, descending the player back to the ground. The basketball is also affected by Newton’s first law during a jump shot. Without external forces such as gravity acting upon the ball once it is released, it will continue to travel in its current direction until gravity pulls it back down. To be able to find the right trajectory for the jump shot the player must judge the force of gravity by the weight of the ball (Benjamin, 2014; Verial, n.d).

Newton’s second law:

Newton’s second law states, “The acceleration of an object is proportional to the net force acting on it and inversely proportional to the mass of the object: F = ma” (Blazevich, 2013).

Acceleration is produced when a force acts on a mass, which is needed to move and change the state of motion of an object. The heavier and greater the mass of the object, the harder and more force will be required to accelerated it. In a sporting performance it is key to try and maximizing the force produced and minimizing the mass of the object; specific technical changes can produce more force, although it can not change the mass of the object (Blazevich, 2013).

This law can be applied to basketball when players are shooting the ball. As the basketball has a constant mass, the player must generate a sufficient amount of force to accelerate the ball towards the basket, where as applying insufficient force or too much may result in the ball not travelling the required distance (Benjamin, 2014; Verial, n.d).       

Newton’s third law:

Newton’s third law states, “For every action, there is an equal and opposite reaction” (Blazevich, 2013).

The third law of motion closely links in with the second law, and answers how force can be applied to ourselves. The law indicates that for every force applied to an object it will have an equal reaction force back in the opposite direction (Blazevich, 2013). If humans apply a force against an object that does not move e.g. the ground, it will produce an equal and opposite reaction against us which we can use to accelerate in opposite direction (Benjamin, 2014; Verial, n.d).

During the shooting movement in basketball, this law is seen in the jump stage and shooting stage. Basketball players apply a ground reaction force through their feet against the floor to create an opposite reaction which propels them upwards into the jump shot. This vertical downwards force occurs when the foot makes contact with the floor (Benjamin, 2014; Verial, n.d). The equal and opposite reaction also occurs when shooting the ball (see figure 4); force is first applied to the ball by the hand to accelerate it towards the basket, an equal and opposite reaction force then occurs from the ball on the hand. This should make the hand accelerate in the opposite direction but it does not, due to other forces acting on the fingers and hand which counteracts the opposite force. The other forces counteracting the force of the ball to the hand include muscles in the forearm, which pulls on the fingers and hand (Academy, 2012).

Figure 4. Newton's third law - Basketball Jump Shot (Academy, 2012)

Centre of mass:

Bodies are made up of individual components or particles that each have its own mass. The weight of a body is the mass of each individual component combined and their acceleration due to gravity (Blazevich, 2013; (Spathopoulos, n.d). The centre of mass is determined by the point of which a symmetrical distribution of weight of each component occurs. In sports performance, manipulating the body around the centre of mass can be an advantage and difference between athletes with the same height and skill level (Blazevich, 2013; (Spathopoulos, n.d).

Balance and keeping the head and eyes forward during the execution of a jump shot is important to improving accuracy of the shot; this can occur by manipulating the centre of mass during the jumping stage of the shot. The centre of mass is raised upwards at first then falls during the jump, this occurs by lifting the feet up under the body making the upper body accelerate downwards in relation to the centre of mass; the extension of the legs accelerates the upper body upwards as the center of mass falls downwards, as shown in figure 5 below (Blazevich, 2013; Chapman, 2008).

Figure 5. Centre of mass manipulated during a jump shot (Blazevich, 2013)

Force:

Force is a biomechanical principle that contributes to the success of an accurate and powerful jump shot. A basketball jump shot utilizes a sequence of chain movements in the body, to generate a production of force to jump and release the ball. In order to produce the greatest amount of power for a jump shot, the shooter must use a summation of forces starting from their legs and ending at their fingertips (Blazevich, 2013). To increase power in a jump shot, force is applied to the ground to accelerate mass upward, transferring momentum in the motion of releasing the ball. The flexion of the knee when producing force, allows for greater muscle activation, consequently allowing the athlete to produce a greater amount of force. Flexion of the elbow is essential in the summation of force process, as regularly extending the elbow reduces the fluency of the jump shot, resulting in a failed shot (Miller & Bartlett, 1996). As the ball leaves the athletes hands, a flick of the wrist motion is the last process of the summation of force. If this wrist action is not performed it could reduce the accuracy of the shot and generate too much force (Kentridge, 2003).      

Impulse Momentum:

Impulse is considered as the product of force and time, and momentum is known as the product of velocity and mass (Blazevich, 2013). Impulse momentum is a biomechanical principle that is used to generate a large amount of force when performing a basketball jump shot. When an athlete is dribbling to the point of their jump shot, their momentum is moving forward. Sufficiently transferring the horizontal momentum (running phase) into vertical momentum (jump) will allow the shooter to accurately balance themselves and shoot a goal. Force and time are incorporated into the movement and consequently “the greater the impulse the greater the change in momentum” (Blazevich, 2013).

Levers:

Muscles and bones enable body parts to move by working together as levers. Levers are used to produce strength, force, speed and range of motion (Knudson, 2007). They comprise of three components:

·      The fulcrum or pivot point which allows the lever to rotate,

·      Load or force which is where force is applied

·      The effort of the force applied by the user (Mackenzie, 2003)

There are also three classifications of levers depending on where each component is located with class 3 being the most common lever in the human body (Mackenzie, 2003).

During a basketball jump shot the shooting arm will act as a level to produce speed and force on the shot; it consists of two class 3 levels, shown in figure 6. The first lever allows the player to produce power in the shot as the fulcrum is located at the elbow joint, with the triceps muscles that connects with the forearm used as the effort to propel the ball. The second lever that is applied during a jump shot occurs at the upper section of the arm, the fulcrum lies at the wrist which allows the player to accelerate the ball towards the basket with a flick of the wrist and shot with accuracy. The force is applied through the forearm connecting to the hand, the load is the ball which is held in the hand.  

Figure 6. Two levers occur in the elbow and wrist during a jump shot

Optimal Technique – Steph Curry:

Figure 7. Steph Curry shooting sequence

Steph Curry is arguably the purest and greatest shooter in NBA history and has revolutionized the art of shooting by his smooth action, quick release and deadly accuracy (Fleming, 2014). NBA analysts and ESPN’s Sport Science have analyzed Curry’s shooting action and consider it to be an optimal shooting technique, with coaches and players using it as a framework to develop and improve on their own technique.    

Curry has the ability to quickly adjust his inertia and change his state of motion for a jump shot by stopping and setting his feet in approximately 0.33 seconds; by not wasting any forward motion it allows his shot to be efficient and repeatable (Highnessfsk, 2013). His forearm position is within 5° of vertical and consistently releases his shot as he is rising 0.06 seconds before the apex of his jump (Highnessfsk, 2013). Curry’s release angle of his shot consistently ranges from 50° to 55° which increases the entry angle of the basket by 19% compared to a 45° shot release, this is an important factor to his 3-point accuracy which stands at an impressive 44% during his career (Highnessfsk, 2013; NBA, 2016). His high release angle also enables him to shot over taller opponents. Curry’s ability to manipulate his centre of mass, increase force production and minimizes forward momentum lost during his jump enables him to release the ball in 0.4 seconds, the quickest release time ever analyzed on ESPN’s Sport Science (Highnessfsk, 2013). He does this by setting his feet softly aligned to the target whilst compressing his right knee, hip, torso, elbow and wrist in a perfect kinetic chain which acts as a vertical spring helping gain extra force coming into his first stage of his shot (Fleming, 2014).

Experiment:

Does increasing the jump shot distance change the angle of the shooting arm or the front leg?

A series of tests were conducted on a sub elite basketball player measuring the shooting arm angle and leg angle at three different shooting distances commonly used in basketball. As seen in figure 8 and table 1 below, by increasing the distance of the jump shot from a short range shot to a mid range shot and finally to a 3-point range the angle of the shooting arm and angle of the front leg decreases. Six shots were attempted at each distance to allow for consistency within the data; the average short range angle of the shooting arm was found to be at 73.5° with the leg angle at 136°, these angles decreased in the mid range shots with the mean being 65° and 121° and continued to decrease as the shot distance increased to the 3-point line with the average angles being 57° and 110°.

The analysis and data shows that as the shooting distance changes, the performance of the jump shot may be manipulated by several variables. These variables include the change of force required from each shot, the demands for greater velocity and momentum, and potential energy. As the shooting distance increases the amount of force needed to be generated through the legs and arms needs to increase as well, to be able to propel the ball over a longer flight path to the basket. The reaction force of the foot and the deep bend of the legs cause the body to be pushed forwards and upwards towards the ring, this reaction force continues through to the shooting arm. By lowering the angle of the legs and deep bend in the knees it helps conserve vertical momentum as the legs start to straighten into the jump. These positional changes in the legs at the different distances allow the player to maximize the potential energy going into each jump shot (Okazaki & Rodacki, 2012). The differences between angles at the various distances is due to the loss of force in vertical displacement and velocity needed to propel the ball, therefore the closer the jump shot is to the basket the lower amount of force needed.

Short Range                                               Mid Range                                                     3 Point Range
     

Figure 8. Shooting arm and leg angle at the three different distances                                                   

Distance	Release Angle (degree)	Front foot leg angle (degree)
Short Range	74	136
	74	137
	71	137
	75	135
	74	136
	73	135
Average	73.5	136
Mid Range	65	123
	66	123
	66	117
	71	120
	60	124
	61	119
Average	65	121
3 point Range	57	111
	59	110
	58	106
	57	108
	56	114
	57	110
Average	57	110

 Table 1. Shooting arm angle and leg angle (degree) data samples

How else can we use this information?

The information provided in this blog discusses numerous biomechanical principles and terms that can be applied to many different sports. Although the information can apply to other sports the primary focus presented is how these principles are applied to the basketball jump shot. It aims to provide basketball players and coaches with information that can be used to improve their jump shot technique as well as understanding why biomechanics are important to the skill.

The biomechanical principles discussed can be transferred into a range of different sports. Understanding how to optimize force production and generate impulse momentum can be used in the sport of rugby. As an athlete performs a long pass, impulse is applied by moving the hands and body through a greater range of motion. The kinetic chain principle is considered to be the most beneficial for coaches. Athletes, who consider the weight of a shot put to be too heavy, can adopt a push-like movement pattern to produce enough force to accelerate the push. Whereas, a strong and generally experienced athlete, would adopt a throw-like movement to push the shot put. Newton’s three laws are also transferred to other sports, an example in tennis is when the serve requires the athlete to jump vertically to hit the ball, then is forced horizontally towards the net. Netball uses very similar movement patterns when shooting, landing, jumping and pivoting. The stance performed in a basketball shot can also be used in a netball shot, to enhance optimal positioning before a pass or a throw.

Overall there are many biomechanical principles that enhance an athlete’s ability to shoot a successful basketball jump shot. Such principles include the projectile angle, ball rotation, power and acceleration that overall enhance the accuracy of a basketball jump shot.

Reference list:

Academy, K. (2012, September 4). LeBron asks about Newton’s 3^rd Law [Video file]. Retrieved from https://www.youtube.com/watch?v=R8qygu1RUOI

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Blazevich, A. J. (2013). Sports biomechanics: the basics: optimising human performance. A&C Black.

Chapman, A. E. (2008). Biomechanical analysis of fundamental human move

Fleming, D. (2014). Sports’ perfect 0.4 seconds. ESPN The Magazine. Retrieved from http://www.espn.com.au/nba/story/_/id/10703246/golden-state-warriors-stephen-curry-reinventing-shooting-espn-magazine

Highnessfsk. (2013, May 15). Sport Science: Stephen Curry [Video file]. Retrieved from https://www.youtube.com/watch?v=HOiH1eVCggw

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Mackenzie, B. (2003). Levers. Retrieved from http://www.brianmac.co.uk/levers.htm

McGinnis, P. (2005). Biomechanics of sport and exercise. Champaign, IL: Human Kinetics.

Miller, S. & Bartlett, R. (1996). The relationship between basketball shooting kinematics, distance and playing position. Journal Of Sports Sciences, 14(3), 243-253. http://dx.doi.org/10.1080/02640419608727708

NBA. (2016). Stehpen Curry Stats. Retrieved from http://espn.go.com/nba/player/stats/_/id/3975/stephen-curry

Okazaki, V. H. A., & Rodacki, A. L. F. (2012). Increased distance of shooting on basketball jump shot. Journal of sports science & medicine, 11(2), 231.

Okazaki, V., Rodacki, A., & Satern, M. (2015). A review on the basketball jump shot. Sports Biomechanics, 14(2), 190-205. http://dx.doi.org/10.1080/14763141.2015.1052541

Pennington, B. (2011). When the feet left the ground. The New York Times. Retrieved 16 June 2016, from http://go.galegroup.com.ezproxy.flinders.edu.au/ps/i.do?id=GALE%7CA253108940&v=2.1&u=flinders&it=r&p=EAIM&sw=w&asid=435568fff723a2d1f4eb09032bc1b271

Spathopoulos, V. (n.d). Center of Gravity. Retrieved from http://www.topendsports.com/biomechanics/center-of-gravity.htm

Struzik, A., Pietraszewski, B., & Zawadzki, J. (2014). Biomechanical Analysis of the Jump Shot in Basketball. Journal Of Human Kinetics, 42(1). http://dx.doi.org/10.2478/hukin-2014-0062

Verial, D. (n.d). How Do the Laws of Motion Apply to Basketball? Retrieved from http://healthyliving.azcentral.com/laws-motion-apply-basketball-1095.html