An Approach to Quantify the Float Effect of Float Serves in Indoor and Beach Volleyball.

Mathias Reiser,Karen Zentgraf,Stefan Kindermann,Stefan Künzell

doi:10.3389/fspor.2020.559277

Abstract

The float serve is an effective weapon to impede the attack of the opposing team. Because of its great importance in indoor and beach volleyball, we measured and quantified the float effect. We recorded 24 float serves of 12 top athletes in beach volleyball and indoor volleyball, respectively, and analyzed them using video analysis. We determined the 3D trajectories of the ball flight and developed two measures to describe the size of the float effect, the mean residuals and the anticipation error. Both were derived from regression models. These measures suggest that the float effect is greater in the vertical plane than in the horizontal plane, both for indoor and beach volleyball. Analyses of ball release velocities suggest that a certain ball release velocity is a necessary, but not sufficient, condition for ball floating. A validation of the float measurements with subjective expert ratings showed a correlation with the horizontal deviations. This study provides a new approach to analyze floating in on-court volleyball serves and broadens the knowledge for float effects in sports.

Highlights

In volleyball, the serve—as the beginning of a rally—aims at making the preparation of the opposite team’s attack as difficult as possible
The highest rating with mean = 2.3 points was found in the beach study and the lowest rating with mean = 0.5 points in the indoor study
The aim of the present study is to analyze the kinematics of ballflight trajectories of volleyball float serves from elite level players and to develop a measure to quantify float effects

Summary

Introduction

The serve—as the beginning of a rally—aims at making the preparation of the opposite team’s attack as difficult as possible. The usage of the float serve at the elite level has increased in both beach and indoor volleyball (Künkler, 2004; Moras et al, 2008; Zimmermann and Thorsteinsson, 2008; Koch and Tilp, 2009; Zimmermann, 2009). At the beach volleyball Grand Slam in Klagenfurt (Austria) in 2008, around 80% of all serves were float serves, 62.5% of those without a jump, and 38.5% with a jump (Koch and Tilp, 2009). A recent study by López-Martínez et al (2020), Quantifying Float Effects in Volleyball which analyzes more than 3,000 serves of elite-level women beach volleyball players, confirms this observation. The advantage of the float serve is that, the reception difficulty is high, the error rate is lower compared to the jump serve (López-Martínez et al, 2020)

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Conclusion