**1. Introduction**

Padel is a racket sport played in pairs (2 vs. 2). The court is characterized by its completely closed girth, as a small-sized grass court (20 × 10 m) surrounded by glass and metallic mesh areas on which the ball can bounce [1]. It has become a mass phenomenon in some countries, such as Spain, and is practiced in more than 35 countries around the world [2]. A professional padel circuit has been created (World Padel Tour), with tournaments in several countries. This development can be attributed to a high interaction between players and a low intensity of actions in a low level of competition [3,4]. Accordingly, the enjoyment and motivation of the players increases, inducing a greater adherence to practice [5–7].

Investigations in padel have increased in the past few years [8]. Research on padel has been mainly focused on describing the match activity and detecting effective performance indicators [9–11]. These investigations have provided primary information such as the rally length (10 to 15 s), the most common actions in offence (volley and smash) and defense (lob), and have highlighted the advantage of the net game. In addition, padel player performance has been characterized by the ratio between winning shots and errors [12]. Furthermore, previous researches have shown gender-related di fferences during competition [13,14]. Higher values have been observed in play time and total time in women over men players, as well as in the number and types of strokes [10]. Therefore, the players constantly try to play in o ffensive positions; for which they use di fferent behaviors and technical-tactical actions, which define di fferent styles of play [12]. The distribution of the di fferent types of strokes, their trajectories and their e fficacy stand out among these behaviours [3–5]. The results of the studies have shown that these variables may also di ffer depending on the gender or the side of the court on which the padel player plays [10,11]. Hence, di fferent performance profiles of padel could exist related to gender and game-side on court [15].

However, there is an alarming lack of investigations examining players' serve and return statistics [16]. One of the most important performance indicators in racket sports is the serve [17]. In tennis, a serve directly wins the point through an ace or indirectly because of the advantage coming from the opponent's imbalance after a grea<sup>t</sup> serve [18]. Thus, tennis players win about 70% of points with the first serve, this percentage being higher in men's singles than in women's [17,19]. Previous studies found that serve was more determinant in tennis doubles, likely due to the presence of the server's partner covering the net [20]. Furthermore, the serve situation could influence point or game outcome in padel, since it allows players to adopt an o ffensive position. In this way, winners scored about 34% more points from the net than losers [9]. However, the serve in padel is di fferent to other racket sports, because of the rules of game. In padel, the ball cannot be beaten as hard as in tennis, and the serve must be an underhand shot from a bouncing ball hit from below waist level. In addition, the e ffect and the side wall can a ffect the serve-return shot [16]. The receiver must play an accurate shot to avoid the serving pair hitting the ball into a tactically advantageous area, so they should vary the direction and height of their return of serve [15,16].

A better knowledge of players' behavior when serving or receiving is extremely useful for developing appropriate game strategies and to design specific training exercises [21]. However, at present little is known about the relationship between the serve and return of serve in padel, other than the fact that the server tends to maintain the tactical advantage until around shot five, when the advantage has dissipated [16,22]. In addition, Zhang and Zhou [23] di fferentiated specific serve tactics in table tennis that were associated with higher scoring rates. Furthermore, some studies highlighted the di fference between first and second serves in terms of how aggressive the return could be [24]. Given that serve and return of serve are two of the most important shots in padel, the purpose of this study was to analyze serve and return statistics in elite padel players regarding court side and gender. This information could help coaches to better understand player strategies and their e fficiency in padel games.

#### **2. Materials and Methods**

#### *2.1. Sample and Variables*

The study was reviewed and approved by the Ethical Committee of the University of Murcia. The sample contained 668 serves and 600 returns of serves from 14 professional matches (7 male and 7 female) of the 2019 Finals World Padel Tour. These tournaments gathered the best pairs in the world, ensuring the highest competitive level in all the matches. A total of 32 players, 16 men (mean (SD) age: 31.18 (7.27) years; height: 181.3 (4.1) cm) and 16 women (mean (SD) age: 28.66 (6.7) years; height: 168.4 (3.7) cm) performed the matches. Variables pertaining to serve and return statistics and point outcome were included in the analysis, following the methodology adopted in other similar studies [25]:

• Serve shots were analyzed regarding the serve number (1st and 2nd serve), court side (right and left), serve direction (side wall, middle and T) and e ffectiveness indicator (winner, error and continuity) (Figure 1).

#### *Appl. Sci.* **2020**, *10*, 6693


**Figure 1.** Illustration of court side and serve and return directions.
