# Effects of Extracurricular Sports in Prepubertal and Pubertal Girls
## 1 Introduction  
Insufficient physical activity has a negative influence on the body composition, physical fitness, and health in children and adolescents [1, 2]. This fact is worsened for those children by high levels of sedentary behaviour [3] or their suffering some health disease [4] because these have a detrimental effect on the development of sports skills [5]. These factors, together with the increasing sedentary time engaged in by children after school [6, 7] might explain why paediatrics are reporting that today's youth is less strong, fast, and light than the previous generations [8].  
This fact is substantiated by the increase in individuals with one, two, and even three syndromes of the 'paediatric inactivity triad' (PIT): 'paeediatric dynapenia', 'exercise deficit disorder', and 'physical literacy' [8, 9]. Thus, further effort in promoting physical activity is required [10, 11]. Adolescence is probably the period in which higher morphological, physical, and physiological changes occur [12]. Many of these changes are influencedby lifestyle factors such as diet, unstructured physical activity, and organised sports participation [13; 14]. Thus, it seems appropriate to control or monitor these parameters in prepubertal and pubertal adolescents. This is even more important for girls, because the changes in their body composition, physical, and physiological fitness occurring in adolescence play a significant role in the impact of the menopause later in the adulthood [15]. Furthermore, childhood and adolescence are key stages in the acquisition and establishment of healthy lifestyle habits [16].  
One of the existing formulas to promote the physical activity and health of girls is extracurricular sport (organised sport practised by children and adolescents after school) [17]. In fact, around half of European children and adolescents take part in these activities [18]. However, girls still show less participation than boys [19].  
Previous studies suggested that the typology of the practised sport can lead to a different body composition, along with physical and physiological adaptations in prepubertal and pubertal girls [20]. In addition, these two growth stages are key periods in the acquisition of morphological, physical, and physiological adaptations [21]. Nonetheless, there is limited information in this regard, as most studies are focused on the bone mineral mass and maturation [22; 23] or do not compare different sports typologies [24]. Consequently, further research is required to understand the role of the typology of the extracurricular sport in the morphological, physical, and physiological adaptations of pubertal and prepubertal girls.  
To provide an initial approach to this gap in the literature, this study aimed to analyse the influence of the extracurricular sport typology (individual and collective) on the body composition, respiratory parameters, and physical fitness of prepubertal and pubertal female girls. Furthermore, this work tested the hypothesis that extracurricular sports participation influences physiological adaptations in both prepubertal and pubertal girls. In addition, we expected that pubertal girls would show greater fat mass, respiratory parameters, and physical fitness than pre pubertal girls.