*2.1. Participants*

This investigation is a part of the Croatian physical activity in adolescence longitudinal study (CRO-PALS) conducted in a representative sample of urban youth (city of Zagreb, Croatia). This study was performed during the second wave of assessments, and all measurements were taken in 2015, during March, April, and May. Information about the procedures of the CRO-PALS longitudinal study have been documented in previous research [26]. In brief, using stratified two-stage random sampling procedures (school level and class level), 54 classes in 14 secondary schools were selected to participate in the CRO-PALS study (schools were stratified by type: grammar schools/vocational schools/private schools). All 1408 students in the selected classes were approached, and 903 agreed to participate (response rate = 64%). One hundred and twenty participants were unavailable on the day of testing or did not complete the FMSTM screening. Of one hundred and twenty participants, one hundred and seventeen were unavailable on the day of testing because they were missing from the school at the time of the measurements, whereas three subjects did not complete FMSTM screening due to lack of time (1 girl and 2 boys). As a consequence, we included data from 783 adolescents. All the participants had to meet certain criteria for the medical doctor to perform the screening process, specifically: (1) not having any pain during the movement screening (i.e., FMSTM testing procedures), (2) not having an acute medical condition that precluded FMSTM testing (neurologic disorders or serious orthopedic trauma such as bone fractures or complete muscle ruptures). Accordingly, 53

subjects were excluded. Therefore, the total number of participants that were analyzed was 730 (girls, *n* = 368, mean age ± SD = 16.6 ± 0.4 years old (yo), mean weight ± SD = 60.1 ± 9.3, mean height ± SD = 166.3 ± 6.4; boys, *n* = 362, mean age ± SD = 16.7 ± 0.4 yo, mean weight ± SD = 71.7 ± 12.5, mean height ± SD = 179.0 ± 7.2). The flowchart of the included participants is shown in Figure 1.

**Figure 1.** Flowchart of included participants.

Children and their parents were fully informed about the purposes of the research, its protocols, and possible hazards and discomforts related to the procedures used. Written consent was obtained from both children and their parents or legal guardians. The study was performed according to the Declaration of Helsinki and the procedures were approved by the Ethics Committee of the Faculty of Kinesiology, University of Zagreb (No: 1009-2014).

### *2.2. Functional Movement Screen*

FMSTM is an instrument designed for the evaluation of mobility and stability of seven functional movement tests: the deep squat, hurdle step, inline lunge, shoulder mobility, ASLR, trunk stability push-up, and rotary stability [17,18]. In the current study, ten novice trained raters used FMSTM according to the official guidelines. All ten raters passed a two-day FMSTM education course by an FMSTM certified practitioner. Despite a large number of raters recruited in this study, previous research reported moderate to good interrater and intra-rater reliability of the FMSTM among novice raters [27,28]. Participants had a maximum of three trials for each test in accordance with the recommended protocol [17,18] while each test was scored on a four-point scale, from 0 to 3, with higher scores indicating better functional movement. Evidence shows that pain can alter movement control [29]. Therefore, subjects were asked if they felt pain during the FMSTM assessment and were subsequently scored with a score of 0 and excluded if they answered this question positively (*n* = 53). In the current study, a functional movement was defined as the movement with a given score of 2 or 3 during FMSTM testing. Also, a score of 1 was recorded when the participant was unable to perform the movement task due to the number of movement compensations present, which reflects the DFM pattern [17,18]. This means that a score of 2 and 3 was an indicator of functional movement, whereas a score of 1 was an indicator of DFM for each of the 7 individual FMSTM tests. If a discrepancy in the scores between the right and left side of the contra/unilateral FMSTM test was observed, movement asymmetry was documented for that specific FMSTM test. We analyzed movement asymmetries for five contra/unilateral FMSTM tests (i.e., hurdle step, inline lunge, shoulder mobility, ASLR, and

rotary stability). Accordingly, number (n) and proportion (%) of subjects who performed DFM or showed movement asymmetry could be calculated in each of the seven or five individual FMSTM movement patterns, respectively. This was the basic step for analyzing the di fferences in the proportion of participants who performed DFM or demonstrated any asymmetry between girls and boys for individual FMSTM tests (i.e., using chi-square tests). In addition, the total FMSTM score was set as an outcome continuous variable and was calculated according to the literature [17,18].
