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Optimizing the Jump Float Serve

This research was conducted to investigate the potential of a new jump float serve technique which would maximize the difficulty for the receiving team in the sport of volleyball.

This project was multifaceted and required collecting biomechanical data from elite players using the proposed and traditional technique, measuring the drag forces on a volleyball in a wind tunnel, collecting 3D kinematics of real serves, and modelling the flight of a volleyball using forward dynamics.

This video shows the traditional, "toss-focused", method of executing a jump float serve. Variations of this method are used by virtually all elite jump float servers. The ball is tossed late in the approach which limits the ability of the server to maximize their jump. This serve was executed by a member of the Gold Medal USA Team at the 2008 Olympcis.
This serve was executed by a member of the Russian team at the 2008 Olympcis. From the receiving team's perspective, it is also very clear which serve is being executed. This player's attempt to fake a spin serve will have little affect. According to the FIVB 30% of all serves at the 2008 Olympcis were float serves. This was up from 15% at the 2006 World Championships.
This serve was executed by a member of the Italian team at the 2008 Olympcis. All of the jump float serves presented on the FIVB webiste demonstrate this method of jump float serve. Players appear to be sacrificing velocity for control.
A participant, from our study, executes the traditional, "toss- focused", serve. The shorter toss ensures the ball is falling slower at impact which increases the probability of hitting the serve without spin. All subjects practiced until they were proficient using both techniques prior to data collection.
A participant from our study executes the proposed, "jump focused", serve. Like a jump spin, the ball is tossed early in the approach, which allows the server to maximize their jump and contact the ball as high above the court as possible. It is also possible to execute a spin serve using this approach, adding a level of deception.
This video shows an elite player executing a spin serve using the proposed "jump-focused" method, which incorporates a two-hand toss without spin. Cuba's Santos was the top server at the 2008 Olympics. With a minor adjustement to the arm swing, she could execute a "jump-focused" jump float serve late into the execution, creating a very challenging scenario for the receiving team.
This video shows one of the male players from our study executing both jump float serve techniques. You can see the differences in the timing of the toss and contact height. The arms are able to contribute meaningfully to jump height with the jump focused method. On average, the 9 participants contacted the ball 16 cm higher with the jump focused method.
This video shows one of the female players from our study executing both jump float serve techniques. In the "toss-focused" technique, the ball is tossed with the right foot forward. In the "jump-focused" technique, the ball is tossed with the left foot forward. This applies to right-handed servers.
We entered the highest contact point for each method from each subject into a program which found the optimal initial velocity such that the ball would just cross the net and land in the court with a maximum amount of final speed. The results for one subject are shown on the right. On average ball speed was significantly greater, intial angle significantly flatter, and flight time significantly less for the jump focused method.
This video shows the actual trajectory of a float serve (in red) and the trajectory the serve would follow in absence of the random motion (in yellow) created by air flowing past the non-spinning ball. The 3D data was collected using multiple high definition cameras and applying Hatze's high precision DLT equations. The errors associated with the data collection were less than 5 cm along all three axes.