What are the biomechanical principles involved in shooting a basketball free throw?

The basketball free throw is one of the most fundamental skills involved in the sport of basketball, and has been described as “The free throw is the single most important shot in the game of Basketball, as close to twenty per cent of all points in NCAA Division 1 Basketball are scored from free throws” (Kozar, Vaughn, Lord, Whitfield, & Dye, 1994). As such is the importance players and coaches place significant time into the skill as it has the potential to decide the result of a game, this skill is essential for all players regardless of size and position. An example which sticks out is that of Shaquille O’Neal who notably struggled with the skill so much through his career that oppositions coaches employed a strategy called “Hack-a-Shaq” which placed him on the line significantly late in games where opponents relied on Shaq missing his free throws.

Figure 1: Kobe Bryant demonstrating his follow through where he has pushed up onto his toes, locked his elbow and snapped his wrist. Bryant has a career 83.8% free throw record. Source: taken from http://basketball-tips-blog.youth-basketball-camps.com/2013_03_01_archive.html As with the execution of any skill there are various techniques which allow for successful execution of a free throw, however most coaches and athletes prescribe to a similar set of guidelines and skill cues which optimizes the chance for the result to be successful. As such a basic guide can be described as, setting feet shoulder width apart at the foul line, with both feet facing forward, right foot slightly in front of left if a right handed shooter, with right big toe in line with the split line of the court right the way to the center of the basket with the knees having a slight bend. This position is effective in a number of ways, having everything in a line from the basket to split line to toe, up the body to elbow and finally to the ball can help eliminate movement off the line which would cause the ball to miss left or right of the ring. By keeping the ball in line there is a greater margin for error short or long of the ring on the shot. This may vary as some players would prefer to line the middle of the body up with the split line, however focusing on a common technique taught is keeping everything in line.  Commonly players then begin a routine which may involve taking various bounces of the ball at the line. These help in a routine where players are able to eliminate any other distractions and focus on something they have performed thousands of times. At completion of the routine, the ball is moved on to the fingers of the shooting hand where the ball is just away from resting on the palm. Often in this stage a player will align their middle finger with the valve or grooves on the ball to continue the theme of keeping everything in line. The opposite hand is also involved as a support for the ball, commonly this stage is referred to as a having an L shape in the arm, in this position a player should be able to just see the basket under the ball, this may vary depending on the individual. From this position the shot is executed, power is generated from the legs before the elbow is locked and the wrist is snapped still in the direction of the basket. A follow through is the final aspect where a player will “hold” their position until the ball travels through the ring, this allows for feedback as to where the shot went right or where it needs to be improved/worked on. The following YouTube clip gives a good fundamental explanation of how a free throw is performed. http://www.youtube.com/watch?v=JYJquICUJCg The Answer: Newton’s Laws Newton’s 1st Law states 'An object will remain at rest or continue to move with constant velocity as long as the net force equals zero' (Blazevich, 2010, p.44). As such in regards to the free throw an athlete must shift from rest to a vertical motion. Newton’s 2nd Law ‘the acceleration of an object is proportional to the net force acting on it and inversely proportional to the mass of the object F=M x A’ (Blazevich, 2010, p. 45) Therefore force must be applied by the athlete in order to accelerate the ball to the ring. Newton’s 3rd Law ‘for every action, there is an equal and opposite reaction’ (Blazevich, 2010, p. 45), the free throw requires vertical or downward force which is applied by the foot making contact with the ground. The ground produces an equal and opposite reaction force, this can accelerate the athlete forward or vertically if the force is great enough to overcome inertia.  This is demonstrated in figure 2. Figure 2: demonstrating how downward force is applied creating an equal and opposite reaction to push vertically. Source: Blazevich, 2010, p.45 The Law of Gravitation: ‘All bodies are attracted to each other with a force proportional to the product of the two masses and inversely proportional to the square of the distance between them’ (Blazevich, 2010, p. 46). Due to the vertical nature of the free throw movement the impact of the gravitational force means that a much larger force is required to accelerate vertically upwards. All three of Newton’s Laws and the Law of Gravitation work together to allow the athlete to come up onto their toes or jump slightly to shoot the Free Throw. To be able to do this inertia needs to be overcome, this happens by having an applied force against the earth, through equal and opposite reaction the result is the shooter coming up onto their toes or in a controlled jump in their shooting motion. Projectile Motion A projection can move at any angle between 0 degrees (horizontal) or 90 degrees (vertical). Trajectory is influenced by the projection speed, the projection angle and the relative height of projection (Blazevich, 2010, p. 25). Projection speed: projection speed determines the distance covered by a projectile, the higher speed projectile is travelling the further it will go. Regarding the free throw the basketball travels vertically, therefore the projection speed will determine the height is reaches before gravity accelerates it back to earth. Projectile angle: refers to the angle the projectile is launched and effects the range of a projectile, an object projected between 0 degrees and 90 degrees will travel vertically and horizontally. Relative height of projection: the vertical distance between the projection point of an object and the point in which it lands. Figure 3: The dimensions of a free throw. Source: taken from http://physicsofbasketball.wordpress.com/2014/05/18/optimal-trajectory-for-a-shot/ Research shows that the optimum angle to shoot a free throw is approximately 51 degrees (Gordon, 1997, p. 495). To have the greatest chance of shooting a successful free throw this angle is suggested due to the ball having the maximum area to go through the ring when the projectile is launched at this angle. A different angle will result in the ball having a smaller area to go through the ring, resulting in the ball to hit the ring and rebound or skim in different directions. To be able to determine the optimum flight path for each individual biomechanical analysis and tests would need to account for different physiological features which may vary the release point, these may include height and length of player’s arms. The Magnus Effect The effect of spin on a basketball shot is quite profound and can as Hubbard states result in a more successful result if correctly executed, as more backspin on the basketball for a shot which falls short or travels too far is more likely to allow the bounce up and drop into the basket (Hubbard, 206, pp. 1303-1308). Alexander (1990) found that when appropriate backspin is placed on the ball the horizontal velocity of the ball decreases if it strikes the ring, as well as causing the ball to rebound downwards of the backboard, thus allowing for a higher margin for error in the shot. The effect of backspin can be generated quite simply by having an emphasis on the basketball resting on the fingers through the motion and snapping the wrist and flicking the fingers. The following video gives a solid understanding to how the Magnus effect influences an objects flight through the air. http://www.youtube.com/watch?v=23f1jvGUWJs Figure 4: Demonstration of the ball being positioned on the tips of the fingers, notice the gap between the palm and the ball. Source: taken from http://www.breakthroughbasketball.com/fundamentals/shooting-technique.html Force Summation Where the basketball is given momentum generated by each part of the body, this is maximized when the bigger muscles are used to fuel smaller muscles, as such power is generated from the larger muscles in the legs opposed to just the arms. As such correct timing, through to the great range of motion will gain maximum momentum (Brancazio, 1981, p. 358). This begins with the legs pushing into the ground, travel through the hips up to the shoulders and arms to the tips of the fingers where the ball is released. Figure 5: How to create backspin on the ball through the snapping motion of the wrist. Source: taken from http://www.basketballcrazy.com.au/108_Newsletter_June_2010.htm Kinetic Chain The free throw can be described as a push like movement pattern where all joints are simultaneously extended, this is demonstrated when the knees and elbow are extended at the same moment. A push like movement is as it sounds a movement where we move as if we are pushing something. This action produces a higher overall force due to the growing forces generated by each joint acting together (Blazevich, 2010, p. 196). These movement patterns are very efficient and can produce highly accurate results due to the nature of the simultaneous rotations in a straight line at the end of the kinetic chain. Work, Energy and Power The relationship between work power and energy can be used to improve the performance of the free throw; these elements are present through the motion when the player bends up from their knees up onto their toes, pushing the ball up towards the basket. This relationship can be described as ‘The amount of work done is equal to the average force that is applied multiplied by the distance of which it is applied. W= F x D’ (Blazevich, 2010, p. 100). This is a product of force and displacement, force provided over a range of object movement. Power is the ‘rate of doing work, work per unit time or the product of force and velocity’ (Blazevich, 2010, pp. 101-102). How else can this information be used? Naturally the free throw in basketball and other sports where a similar shooting action is present contain comparable biomechanical principles. The netball shot is one such action, where a player will align feet, generates momentum from bending their knees and push up from the ground onto toes. However there is a difference in the follow through of the two shots where in a free throw the elbow is locked and wrist is snapped of the shooting hand compared to the netball shot where both hands are used in the follow through. Adding to this is the fact that a free throw is executed without any active defensive pressure, where the netball shot is often executed with at least one defender active in between the shooter and the ring. Similarly the set shot in basketball commonly referred to as a “catch and shoot” requires similar principles to the free throw. The major difference being the use of the legs to create greater force in order for the ball to travel a greater distance to the basket, the aspect of active defenders is also another aspect regarding the set shot. There are numerous aspects of any sport which similar biomechanical aspects are applied, examples in the sport of basketball can include the use of newton’s laws in particular newton’s second law as well as, vertical impulse, work, power and the kinetic chain. An example of this could be the aspect and skill of rebounding where the maximum jump height and energy required can be utilized. The movement of maximal jumping also relates to skills in other sports such as, the volleyball spike or block where repeat efforts of maximal jumping may be required.  Various aspects are present in multiple sporting situations, for example the Magnus effect is present in numerous sports, including soccer, cricket, baseball and golf This information can lead to successful teaching of the basketball free throw, accurate analysis of players’ individual techniques will be better informed by coaches, teacher, parents and fellow players. Reference List Alexander, M. (1990). 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