Force Summation & The Kinetic Chain

While the final result of the jump shot is determined by the hands, wrists and fingers, it is important to note that the entire body is responsible for the force summation in regards to the jump shot. The image below shows a visual representation of the working muscle groups throughout the entirety of the basketball jump shot.

It clearly shows the activation of the calf and quad muscles in the initial leg bending phase, followed by the activation of the trunk, up through the shoulders, biceps and triceps, through the wrist and then finally through the fingertips upon the release of the ball. The justification for using more muscle groups is that the shooter is able to generate significantly greater force (Blazevich, 2007), which in turn provides a greater velocity for the ball to be released at. It has been found that between 65% and 85% of missed jump shots are due to the initial ball velocity upon release from the hand being too low (Knudson, 1993).

In terms of the kinetic chain, due to the activation of the calf and quad muscles, ankle, knee and hip joints prior to the activation of the upper body, the basketball jump shot can be classed as a throw-like movement pattern (Blazevich, 2007).  The best understanding for how a throw-like movement can generate high speeds, is due to the rapid shortening speeds of the tendons in the body (Blazevich, 2007). The tendons in the fingers and wrist are ultimately responsible for the speed of the ball upon release, however, the stretching of the tendons in the legs is essential to the jump shot process (Blazevich, 2007).  Referring back to the picture above, the clear angle made at the back of the knee provides angular momentum at the base of the body. Notice in the picture above that the shooter keeps his legs straight while he is in the air. By jumping straight up, and keeping their legs this way, the player is able to conserve their upward vertical momentum, allowing the player to manipulate their centre of mass in order to ‘hang’ in the air. This ‘hang-time’ is often used to keep the head still in order to increase the accuracy of the shot (Blazevich, 2007). The image below provides a visual representation of how the player should apply force directly straight down in order to have the reaction force from the ground send them straight up. The ability to jump straight up is promoted by the stable base of support provided by the legs, which minimizes any kind of horizontal movement in the process of the shot (Knudson, 1993).  A slightly staggered stance that widens the base of support is bound to increase stability prior to the skill execution phase. If the jump is attempted while off balance, the accuracy of the shot is significantly altered.

 Notice the optimal straight up and down force represented on the left, compared to the reaction force against the player on the left sending them further away from the basket, ultimately making the shot harder to effectively complete. While elite NBA shooters such as Kobe Bryant, picture below, may be able to make shots when they are forced to jump in a way that is not optimal, the preferred shooting technique is jumping vertically.

 

It is important to note that jump shot techniques vary from player to player based on what feels comfortable for them, effectively there is no ‘optimal’ technique. For example, Steph Curry, who is widely considered the greatest shooter in the NBA after making the most amount of 3-pointers (402 3PM at 0.454%) in a regular season in NBA history (ESPN.go.com, 2016), has a slightly different shooting technique than LeBron James for example. In terms of optimal components of the skill, both Curry and James have their legs straight to allow them to hang in the air. It is clear, however, that players need to adopt a few techniques that allow for successful shots in order to adapt to different situations on the court (Bartlett, Wheat, Robins, 2007).