This study was a novel attempt to analyse the relationships between selected fitness characteristics and some objectively measured lifestyle determinants in a group of elite young table tennis players in Poland. In recent years, researchers have been increasingly interested in the correlations between various lifestyle determinants and the level of physical fitness among adolescent athletes [41, 42]. However, no scientific reports exist on the relationship between environmental factors such as leisure time activities and the level of general and special fitness among young table tennis players.
Many authors have attempted to assess the physical fitness of young people practicing sport, including table tennis, treating it as an isolated variable, as exemplified by the research of Ulbricht et al. [43], Kramer et al. [44, 45] and Faber et al. [5] The results presented in the study show that all the examined players presented an average level of general physical fitness (OF = 424.1 ± 41.69) estimated according to standards for Polish youth [33]. The results of other studies, including Żak et al. [46] and Łubkowska and Troszczyński [47], show that athletes practicing other sports (e.g. badminton, Olympic taekwondo or swimming) who are the same age as the examined table tennis players achieved a similar OF value.
The higher level of OF of girls practicing table tennis, compared to their male peers, can be explained, among other factors, by their faster biological maturation at the investigated age [48, 44, 49]. A comparative analysis of the average results of girls and boys showed that not all IPFT results were above the average classification standards (Table 2). In the hand strength test, both girls and boys obtained results below norms. An analysis of the results of dynamometer measurement of hand strength of girls and boys reported that this test was insufficient to represent total strength at this stage of development [50].
The girls also obtained worse results in the test of flexibility. The low point indicator of the players in this sample is described in the literature on the subject [51, 52]. The optimal level of flexibility is, however, necessary in table tennis for the correct performance of technical elements [28]. Therefore, there is a need to increase the training measures that shape flexibility in the motor training process of these young players. Table tennis belongs to the group of sport disciplines where the level of coordination and speed skills, especially of the upper limbs, should be at the highest level [53–56]. This study showed that the table tennis players obtained the best results in the SHR test assessing the level of these abilities. These results are consistent with those obtained for players on the Polish youth teams of the same age in other sports, including swimming, Olympic taekwondo, football, acrobatics, boxing, judo, canoeing, cycling, basketball, athletics, handball, volleyball, fencing, triathlon, rowing and free wrestling [57, 47].
The assessment of the level of special physical fitness in young top-level table tennis players has not yet been widely studied [58]. Sport-specific technical skills are predominant factors, although a complex profile of physical performance factors is also required. For this reason, accurate and reliable methods of evaluation are very important for the training process. The review of literature revealed that most of the studies designed tests for speed or accuracy of basic skills, other aspects of physical fitness or counterattack [59, 23]. As determined by Kastikadelis [23] contemporary playing techniques in table tennis are very important for target precision counting and the accurate reflection of players’ strokes. The TTSBT is a reliable test battery that focuses on the evaluation of technical skills and the progress of table tennis performance of young players [23, 21].
However, so far, no appropriate test standards have been developed for young tennis players based on their age; the only available standards are based on the gender of the players [32]. When analysing the results obtained by the examined players in relation to the available standards, it should be noted that in T1 and T2, both girls and boys were classified as having a good and a very good level of special fitness, respectively. In T3, on the other hand, the level was basic and good [32]. The TTSBT results obtained by girls did not differ significantly from the boys' results (Table 3). Perhaps this is because the individual level of differentiation of the respondents was low (high group homogeneity) and the sample size was limited. Similar relationships have been reported by Chillon et al. [60], among others. However, differences based on the stage of training were noticeable, probably because of the significantly higher volume and intensity of training [13, 9].
The relationship between the tests characterising the level of general and special physical fitness of young players is interesting. The results of T1 and T2, whose main purpose was to estimate each player’s capacity to react quickly to unpredictable throwing of balls were significantly connected with the upper (BAH) and lower (SBJ) body power of the players (boys and girls, at both stages of training) and with their running and speed abilities (SHR and R50m). The results of the study correspond with the findings of Kramer et al. [44] and Faber et al. [5], who studied junior elite tennis players in the Netherlands. In turn, the results of T3 were connected with upper body power (BAH) and body agility (SAR) of young players (Table 4). This was due to the characteristics of the test sample, with the main purpose to estimate the players’ capacity to perform lateral, lateral with pivot, profundity and mixed displacements during a short period. A possible reason for these findings is that agility, speed and strength of upper limbs includes dynamic movements requiring high muscle power, so one would therefore expect these performances to be closely related. Another explanation for the close correlation between these skills may be the same energy systems that each movement type demands [60].
One of the main goals of this study was to identify young table tennis players’ leisure time physical activities and SB between training. The level of PA (MVPA and VPA) and sedentary lifestyle (SB) outside the training of young athletes will allow trainers to understand the interests of their players better and may affect the individualisation of the training process. According to Exel [61], it is difficult for young athletes and trainers to determine the best choices of leisure time strategy, but individualisation of needs and a context-based approach in daily life schedule structure seems to be critical. For young athletes, considering table tennis performance, PA and SB profiles should also be considered key to evaluating, preventing and treating overtraining symptoms [62]. The level of PA and SB between training may also highlight issues related to the health parameters of young athletes. PA at moderate to vigorous intensity can help prevent weight gain and maintain a healthy body weight in children and adolescents [63]. Current PA guidelines for children and youth aged 5–17 years recommend at least 60 minutes of MVPA per day and VPA at least four times per week [64], but nationally, only a small proportion of youth meet these guidelines [65]. Moreover, more than two thirds of European youth can be categorised as insufficiently active [66, 61]. In our study, MVPA standards were met by 38% of young table tennis players, and VPA standards by 66% (Table 5). Although young athletes mostly performed MVPA above the recommended level and were also active in their leisure time, sedentary lifestyle habits associated with daily activities and social behaviours of young people were also visible. According to Pearson et al. [67] young elite athletes prefer to sit down as often as possible to aid recovery and prevent fatigue. This suggests that some active children choose to spend considerable time being sedentary (TV watching, cell phone interaction, recreational computer use or other forms of screen-based entertainment), as confirmed by the research of de Rezende et al. [68]. Thus, it can be assumed that the studied young elite table tennis players, exposed to many hours of training and competition, more often adopt a sedentary lifestyle, treating it as a form of rest and relaxation. This is also reflected in the forms of PA undertaken by the examined table tennis players (girls and boys) in their leisure time (walking and cycling), which are characterised by low physical effort. The results of this study do not confirm completely the assumption of a difference in terms of gender and stage of sport training in the leisure time activities of young table tennis players.
The main limitation of this study that should be highlighted is that it assessed only young Polish table tennis players, and further studies should be performed with athletes of different nationalities. The relatively small group sizes present another limitation. The current study did not examine other potentially influential factors (such as differences in maturation, which might influence the physical fitness results, family leisure time and sport traditions, motivation, parental and peer support, training facilities and school policies), which might also be considered a limitation. However, the similar cultural backgrounds of the examined players (coming from urban areas of cities) may be an advantage.