**4. Discussion**

This study aimed to determine functional movement status in a general adolescent population. The main finding of this study is that adolescent boys showed a higher proportion of DFM and movement asymmetries in the larger number of FMSTM tests compared to adolescent girls. More specifically, boys demonstrated a higher proportion of DFM and movement asymmetries in the inline lunge, shoulder mobility, and ASLR tests, which could potentially predispose them to higher injury for lower and upper extremities [5]. On the other hand, girls demonstrated a higher prevalence of DFM in the push-up and rotary stability tests. A low score in the trunk stability pushup test and rotary stability could indicate inadequate reactive stabilization of the trunk muscles and a deficit in the upper body strength in the female adolescent population [18]. For this reason, adolescent girls in the current study could be more prone to su ffer from a higher risk of lower back injury [30]. On the other hand, girls slightly outperformed boys in total FMSTM score (12.7 vs. 12.3 points) which further emphasized the aforementioned sex di fference in functional movement during the mid-adolescent period.

In the current study, when the sample was stratified by sport participation, subgroup analyses showed similar results when compared to the findings of the initial analysis (i.e., for the total sample). The main di fference between findings from the total sample and subsample was in the total FMSTM score. More specifically, athletic girls outperformed athletic boys significantly (13.2 vs. 12.3, respectively), whereas in the subgroup of non-athletic participants sex di fference was not noted. However, when the proportion of DFM and asymmetries are considered, similar patterns of movement dysfunction can be seen in both the athletic and non-athletic subgroup of participants, as well as within the total sample of mid-adolescents. This could possibly mean that sport participation probably does not influence functional movement status in the adolescent period since similar patterns of movement dysfunction were observed within the aforementioned groups and subgroups of mid-adolescents. Indeed, according to the current literature, in both the general and athletic adolescent population, most evidence demonstrates that females have a higher total FMSTM score compared to males [8–10,12,15,16], although two studies reported opposite results [6,14]. In the study done by Abraham et al. [14], a large age span (10–17 yo) among participants revealed that pre-pubertal and pubertal subjects were included in the sample and all inactive children were excluded, which could potentially lead to higher mean values. Some researchers found no sex difference in total FMSTM score [11,13], which could be potentially contributed to different populations studied (8-11 yo) and much smaller sample sizes (*n* = 77 and *n* = 58, respectively). Concerning individual FMSTM patterns, evidence almost consistently shows that, in both general and athletic adolescents, same sex differences are present. More specifically, female adolescents generally show a better quality of movement in flexibility/mobility tests [10,11,13,16] while boys are better at push up and rotary stability [6,11,13–16]. Reported results from previous studies are in line with the findings of our study. What our study adds to the existing body of knowledge is that the same sex differences in functional movement exist in the population of mid-adolescents.

Still, it remains unanswered as to why these sex differences in the functional movement patterns are present in the adolescent period. Therefore, three possible explanations for observed phenomena should be considered. *(1) Physiological*—*potential e*ff*ect of maturation on muscle performance*: girls scored higher in the inline lunge, shoulder mobility, and ASLR, which could be due to higher mobility/flexibility demands of these movements [17,18]. This could be further explained with previous findings that reported greater mobility among girls compared to boys during the adolescent period of growth [31]. Since higher values of upper body strength are reported in boys compared to girls during adolescence [32], this could explain the discrepancy that was found in the upper body test (i.e., trunk stability push-up). *(2) Anatomical*—*potential e*ff*ect of sex on joint morphology*: Reported differences in the aforementioned FMSTM patterns could be possibly due to different architecture of the pelvis, hip, and shoulder since adolescent girls demonstrate more general joint laxity, hip anteversion, and tibiofemoral angles compared to adolescent boys [33]. Furthermore, development of the adolescent female pelvis from fifteen years of age and onward differs considerably from males, which can contribute to observed discrepancies in reported DFM in the current study [34]. The difference in the proportion of DFM in lower body patterns reported in the current study could be due to different hip architecture since it has been shown that adolescent girls have a different orientation of the acetabulum compared to boys [35]. More specifically, girls from the age of 13 to 17 have increased acetabular anteversion compared to boys [35]. This could possibly explain why girls performed better on tasks that demand active hip flexion (i.e., inline lunge and ASLR), whereas the different orientation of the acetabulum in boys could limit hip flexion movements. What could be concerning is that a higher prevalence of DFM observed in lower body patterns among boys could predispose them to a higher risk for developing hip orthopedic abnormalities (i.e., femoroacetabular impingement) [36]. *(3) Sociocultural—potential e*ff*ect of cultural engagement in specific sport activity*: adolescent boys tend to engage more in sports such as soccer and basketball which have a high prevalence of unilateral and asymmetrical movement patterns [37]. This could further facilitate movement asymmetries seen in shoulder mobility and ASLR tests. On the other hand, girls participate more in sport activities that have an aesthetic component (i.e., dance, ballet, etc.) where specific unilateral movement patterns are not emphasized or trained in isolation [37]. Given the fact that in the current study more boys were engaged in sport activity compared to girls (48% vs. 25%, respectively), the aforementioned explanations could possibly explaine behind mechanism for observed discrepancies between adolescent girls and boys concerning movement asymmetries.

This study has several strengths. First, this is the only study that provides information about dysfunctional movement as well as movement asymmetries assessed by FMSTM in a large sample of urban adolescents. Second, this is the first study to investigate a highly age-homogenized adolescent population (16–17 yo). Third, current research is based on a reasonably large number of participants (*n* = 733). All this allowed for more precise information about sex differences in a functional movement to be investigated. However, there are also several limitations that need to be considered while interpreting this data. This study investigated a population in the urban area, thus excluding children from rural areas which may affect the generalizability of the results in the context of the whole adolescent population. The large number of raters used in this study can be a potential drawback, although good interrater agreemen<sup>t</sup> in FMSTM scores has been repeatedly reported [27,28]. Despite all

this, the results of the present study give comprehensive data about a functional movement among the adolescent population.
