# Does Higher Maturation Make Age-Grouped Swimmers Faster? A Study on Pubertal Female Swimmers
## 1 Introduction  
The performance of young swimmers has been discussed in many studies considering a variety of indices: kinematic [1], physiological [2], biomechanical [3], and anthropometrical [4]. [PERSON] et al. [5] claimed that the swimming performance of adolescent swimmers was determined mostly by anthropometrics, biomechanics, and energetics. [PERSON] and [PERSON] [6] stated that when trying to separate performance progress among adolescent swimmers as a result of the training process, the variability caused by growth and development was one of the most important challenges. It is emphasized by the fact that the 100 m freestyle performance of youth swimmers is, by some researchers, believed to be determined mainly by anthropometrics (in boys and girls) [7], but when girls only areconsidered, it could be that the correlation between swimming performance and somatic indices is not that high [8]. Aerobic power is significantly related to the pubertal development/growth of the adolescent swimmer [9]. [PERSON] et al. [10] discovered no correlation between peak oxygen uptake (\(VO_{2}\)_peak_) and the swimming performance of young female swimmers at a wide range of distances (from 50 to 1000 m). Similarly, [PERSON] et al. [11] reported that \(\dot{VO}_{2}\)max values were not significantly correlated to the 100 m front crawl performance of adolescent female swimmers. Higher values of \(\dot{VO}_{2}\) could be connected to higher endurance and speed of swimming. [PERSON] et al. [12] presented that \(\dot{VO}_{2}\) increased exponentially as a function of swimming velocity; surprisingly, they did not find any correlation between \(\dot{VO}_{2}\) and swimming speed, maybe because of the importance of the anaerobic component. The influence of maturation on anaerobic production has been dealt with in science since a study by [PERSON] et al. [13]. During a swimming race, it takes less than a minute before aerobic metabolism contributes to 30-45% of total energy production [5]. [PERSON] et al. [12] discovered that accumulated blood lactate values in samples collected 3 and 5 min after maximum 100 m front crawl trial were significantly correlated to the time of the mentioned trials (\(-0.525\) and \(-0.574\); \(p\leq 0.05\)). Swimming technique, described by the indices of stroke rate (\(SR\)), stroke length (\(SL\)), and stroke index (\(SI\)), has been identified as one of the main factors influencing adolescent performance [4; 14]. The growing and maturation processes of adolescent swimmers result in anthropometrical changes and, thus, influence technical parameters and performance [15; 16]. [PERSON] et al. [12] concluded that sprint swimming performance was likely to be dependent on the maintenance of high \(SL\) and on a stable increase of \(SR\). Improvement in swimming technique is mainly achieved by proper and systematic training. Tethered swimming constitutes a reliable and often executed test of in-water strength abilities of young swimmers [17]. [PERSON] et al. [18] linked tethered swimming strength with anaerobic potential and performance at short and middle distances. [PERSON] et al. [19], after analyzing data from their longitudinal studies, stated that the peak for static strength among girls interacted with the maturity status from age 11 to 14. It is necessary to constantly monitor the strength abilities of swimmers because the force exerted while stroking is among the main factors providing progress in performance [20]. The aim of this study was to select, from the variety of indices (anthropometrical, physiological, biomechanical), the ones that best explain the 100-m front crawl performance of the involved age-group female swimmers. An attempt was also made to identify, by performing a cluster analysis based on biological age (\(BA\)), groups of swimmers characterized by similar sets of indices to examine if there was any diversity in terms of anthropometrics, performance, and metabolic or biomechanical potential in potentially homogenous groups of swimmers (calendar age).