Kinetic Chain
A kinetic chain is a where linked muscle groups perform rigid movements to create a greater force summation (McLester & Pierre, 2008). There are two types of kinetic chain make ups, which are the push-like pattern and the throw-like pattern (Blazevich, 2012).Both types of kinetic chain movement patterns are used in the tennis serve and both serve as one of the key sources of power and accuracy in a tennis serve.
Push-like pattern
The server using the push like pattern to extend their legs to connect with the ball
The push-like pattern is where all the muscles extend in a simultaneous motion to create a pushing force (Blazevich, 2012). In the serve, the lower half of the body must push off the ground to create an extensional force. This enables the player to execute maximal power output when connecting with the ball. The picture above shows a push-like kinetic chain as my feet push off the surface of the court. This force then travels from my toes to my legs and hips before summating into my upper body which in turn increases the force I am able to apply to the tennis serve.
Throw-like pattern
The other kinetic chain pattern is the throw-like movement pattern. According to Blazevich (2012), the throw-like pattern differs to the push-like pattern as the joints extend sequentially rather than simultaneously to create a greater force summation. In the tennis serve wind up phase, elastic energy is stored as the racquet arm is stretched behind the back (see strain energy). During the connection phase of the serve, the elastic energy stored in the muscles is released sequentially through the racquet arm creating a greater force. Firstly the back and shoulder muscles extend. This force is then transferred to the bicep and tricep muscles, to extend the lower arm. The elbow then extends to extend the forearm. In the final part of the motion, the energy is transferred from the forearm to the wrist, resulting in a snap-like action which releases the build-up of elastic potential energy (see strain energy). Optimal timing and smoothness are key elements in producing an efficient serve in terms of force output and transfer of potential energy (McLester & Pierre, 2008). A staggered motion in this wind up and connection phase could result a less efficient serve technique which could contribute to a lower power output on the ball. My serving wind up is a prime example of where this could be improved. This is due to the fact that my action often seems to stop between each phase of the kinetic chain.
This video shows the kinetic chain effect in the racquet arm. Notice the wrist flick when the player makes contact with the ball.