## 1 Introduction  
In the past few decades, there has been a great interest in finding models to identify future sports talent among children and adolescents [1]. These talent identification programs often include the analysis of physical performance and kinanthropometric variables as a result of their influence on elite performance in sports [2; 3; 4; 5; 6]. More specifically, volleyball is characterized by explosive actions, which makes the physical condition of great importance in performance [7; 8]. Due to the rules of the sport, height, arm span and leg length could allow the differentiation of high-level players [9], together with specific physical abilities such as vertical jumping and coordination in agility tests [10].  
However, the characterization of the physical and kinanthropometric requirements of athletes should be approached with caution when extrapolating values to young growing athletes, as biological changes occur during this stage of maturation that may affect these variables [11]. Along this line, many talent identification programs base their selection on size and physique, dividing athletes by age groups, without taking into account that as the maturation process continues, these characteristics could become equalized [2].  
Biological maturation seems to have a significant relationship with kinanthropometric and fitness variables in adolescent male athletes, with early matuvers showing higher values in kinanthropometric and fitness tests, perhaps as a result of hormonal changes that occur during biological maturation [2,3]. For this reason, much attention has been paid in recent years to the relationship between biological maturation, physical fitness and kinanthropometric characteristics [3]. The age at peak height velocity (APHV) has become one of the most widely used indicators to monitor the gap between the chronological age and biological maturation of individuals [12,13]. A widely used and validated method to assess APHV is based on regression formulae from kinanthropometric variables [13].  
Presently, the participation of female athletes in elite sporting events is on the rise [14]. In spite of this, scientific knowledge on the factors that affect the sports performance of women is lower than for men [14]. It is known that the maturation process occurs unevenly between boys and girls, with differences observed in the age of onset of maturation (between 9 and 14.9 years in girls versus between 12 and 15.8 in boys) [12] and in hormone concentrations related to the process of body change [15]. However, studies on the female population are scarce, and there is little evidence on whether this phenomenon also occurs among adolescent girls [16,17], although the study of the influence of biological maturation on kinanthropometric and fitness variables in female athletes could help to clarify key points in the identification of sporting talent [2,3]. Knowing this, it is possible that girls whose maturation process is more advanced would show higher values in kinanthropometric variables, as well as better performance in physical fitness tests compared to their chronological age peers.  
Notwithstanding all of the above, there are no studies that have analyzed the differences in kinanthropometric variables and physical fitness in growing volleyball players, neither in male nor in female populations, according to the maturity status classification [3]. Therefore, the aim of the present research was to analyze the differences in kinanthropometric characteristics and performance in physical fitness tests according to biological maturation, as well as to determine if age, biological maturation or kinanthropometric variables could predict better performance in physical fitness tests in adolescent volleyball players.