*Subgroup Analyses*

Since five subjects did not report sport participation status (due to being absent from school), all subgroup analyses were based on 725 participants. When the sample was stratified by sport participation, within the group of non-athletic participants there was no sex di fferences in the total FMSTM score (girls vs. boys, 12.6 vs. 12.2, respectively, *p* = 0.11). However, among the athletic subgroup of adolescents, girls significantly outperformed boys (13.2 vs. 12.3, *p* = 0.002). Among the non-athletic adolescents, boys demonstrated higher proportion of DFM in three tests compared to girls (inline lunge: 24% vs. 33%, *df* = 1, *p* = 0.032; shoulder mobility: 29% vs. 41%, *df* = 1, *p* = 0.004; ASLR: 7% vs. 34%, *df* = 1, *p* < 0.0001). On the other hand, girls underperformed in push-up and rotary stability tests (push up: 80% vs. 44%, *df* = 1; *p* < 0.0001; rotary stability: 56% vs. 47%, *df* = 1; *p* = 0.04), while in squat and hurdle step patterns no sex di fferences were shown (*p* = 0.25–0.66). In addition, non-athletic boys showed a lesser number of asymmetries compared to non-athletic girls in the shoulder mobility test (50% vs. 67%, *df* = 1, *p* = 0.01), while other four uni/contralateral tests failed to reach significance (*p* = 0.06–0.4).

Among the subgroup of adolescents who have participated in sports, girls showed a lesser proportion of DFM compared to boys in inline lunge (13% vs. 31%, *df* = 1; *p* = 0.0009), shoulder mobility (20% vs. 51%, *df* = 1, *p* < 0.0001), and ASLR (11% vs. 28%, *df* = 1, *p* = 0.001). On the other hand, boys exhibited a lesser proportion of the DFM in the push-up test (43% vs. 85%, *df* = 1, *p* < 0.0001). However, there was no significant sex di fference observed in squat, hurdle step, and rotary stability (*p* = 0.41–0.61). Concerning movement asymmetries, athletic girls demonstrated a lesser proportion of the asymmetries only in the ASLR movement pattern (13% vs. 22%, *df* = 1, *p* = 0.018).
