Gender Based Comparison and Effects of Multi-Year Physical Exercise Program on Motor Skills in Preschool Children

The aim of this study was to determine gender differences in the level of motor skills and effects of a multi-year exercise program on the level of motor skills in 161 preschool children (5-6 yo). Patricipants were deployed into one control and three experimental groups. Motor skills were assessed with the Bruininks-Oseretsky Test of Motor Proficiency (BOT-2). To determine difference in scores for each BOT-2 tests between control and experimental groups, one-way ANOVA was used for girls and boys separately while two-way ANOVA was employed to determine difference between the gender in the overall BOT-2 score. The results indicates that one-year multilateral exercise program has a positive effect on the level of motor skills in preschool children. Interestingly, additional years of participation in exercise program yielded in maintenance of acquired motor skills level. Also, exercise program affected more girls than preschool boys considering both individual and composite BOT-2 scores. According to the findings of this study, presented exercise program could have potential benefits on multilateral development of the motor skills in preschool children which could facilitate balance of locomotor and manipulative skills. Therefore, integration of multilateral program intended for preschool children could be considered for implementation within the kindergarten curriculum.

In addition, only healthy children were included in the study and out of the total sample of 170 children, 9 subjects dropped out, thus the total number of participants was 161. This study was done according to the declaration of Helsinki and the Ethical suited for children from 4 up to 21 years of age and measures motor precision, motor integration, ambidexterity, manual coordination, balance, bilateral coordination, speed, agility and strength. The final test result is a standardized overall motor score which was calculated according to the literature [18].
The physical exercise program in the kindergarten has been implemented since 2015/2016. The experimental groups were actively involved in the physical exercise program and they were included in the program as follows: G3 starting from 2015/2016, G2 from 2016/2017, and G1 from 2018/2019. One pedagogical year was defined as the period of 10 months and included the physical exercise program of 40 weeks, containing 120 training units (hours). This means that when the measurement took place, the total number of hours in physical exercise program for G1 was 120, followed by the G2 with 350 hours, and the G3 with 470 hours. The exercise program was organized three times per week (three sessions) with duration of 60 minutes per each session while two physical education teachers were responsible for the realization, control and assigning of the workload for the children. Physical education teachers systematically planned, programmed and conducted physical exercises with the children. The physical exercises program was focused on a multilateral psychophysical development of the child. Also, within the physical exercises program, a schedule with the distribution of the workload through program contents was defined. Within one school year, the participants were introduced with basic gymnastics exercises, various jumps and runs, polygon obstacles, manipulation of various props and they have learned the basics of team sports such as: football, handball, basketball, and volleyball (Table 1). During the implementation of the physical exercises program, the primary task was to facilitate the development of the child's positive life habits and the development of cognitive and motor skills. Children's diet had been planned according to the recommended amounts of energy to be consumed in a day, in accordance with the daily workload. This was done in accordance with the provisions of the kindergarten teacher (Table 1).  First, descriptive analysis for basic anthropometric variables was done for girls and boys separately. Second, to determine difference in scores for each BOT-2 tests between control and experimental groups, one-way ANOVA was used for girls and boys separately. To investigate difference between the gender in the overall BOT score, twoway ANOVA was employed, using gender and years of experience as fixed factors. The level of the statistical significance was set at p < 0.05.

Results
Body height, body weight, and BMI averaged (±SD) 117 ± 6.2 cm, 21.8 ± 4.1 kg, and 15.8 ± 2.1 kg/m², for total sample respectively. A two-way ANOVA did not reveal significant interaction between the gender and the years of exercise (p=0.48). However, analysis has shown a statistically significant difference in the overall BOT-2 test score among both girls and boys between most groups (see Table 2).  Figure 2.  *represents a statistically significant difference between the groups (p<0.05).

Discussion
The results of this study indicates that one-year multilateral physical exercise program has a positive effect on the level of motor skill in preschool children. What is more, our results show that additional years of participation in exercise program yielded in maintenance of acquired FMS level. Also, evident sex difference was observed in effects of exercise program on FMS level. More specifically, findings of this study suggest that program affected more girls than preschool boys considering both individual and composite BOT-2 scores.
Regarding sexual dimorphism, differences were found between CG and experimental groups in all eight component of movement skill among girls, while among boys these difference were evident in only three tests (see Fig 2. and 3.). Effect of one-year additional exercise program on FMS was evident in both sexes (differences between CG and experimntal groups in BOT-2 score were 56 and 64, for boys and girls respectively).
However, additional three and four-year participation in exercise program did not significantly improved the FMS among children. It is important to note that aforementioned finding does not imply that children do not need to participate in additional program for more than one year. What is more, this kind of program should be  [19,20] which suggest that children should accumulate at least 180 minutes of physical education through preschool education activities each day while the guidelines point to 11,500 steps daily [21]. However, in this study we did not control for physical activity level and above-offered potential explanatins should be taken with cautious. Another possible reason for these findings could be due to stabilization of learned movement skills after one year of practice where any additional year spent practicing would not yield in improvement of movement skill. However, authors point out that maintaing acquired level of FMS through all years of kindergarden education should be priority in population of preschool children. Still, more researches are needed in order to explore aforementioned effect on movement skills in preschool children.
The results of this study differ from the results of a more recent study [22] which included a sample of 31 participants (5.59 ± 0.77 yo). Results of Šalaj et al. [22] showed that there was no sex differences in gross motor quotient, and locomotor or manipulative skills among preschool girls. However, differences were found in gross motor quotient and locomotor skills when comparing selected with the non-selected gymnast girls. Also, our overall BOT-2 test results differ from the results in the study done by Kezić et al. [23] (n=70, 6.0 ± 0.5 years), where participants showed lower results in the following tests: hand coordination (1 to 12.00), bilateral coordination (2 to 7.00), and strength (0 to 8).
Furthermore, Guo et al. [24] found a significant correlation between the effectiveness of motor skill and physical activity (r = 0.14-0.17) where they stressed that early interventions of programmed physical activity are crucial for development of FMS.
Although these studies examined children with the same chronological age, the results of our study differ from the results of the above-mentioned studies. This could be probably because aforementioned studies had a differently oriented concept of exercise program.
Also, the results of above-mentioned researches show a lower level of locomotor and manipulative skills. Although the results of this study are different from aforementioned researches, this study gave new insights about impact of various exercise programs on motor development of the children.
This study has three advantages. First, this study included three experimental groups with different previous motor experience and different exercise volume, which can allow better conclusions about effects of exercise program on the measured motor skill parameters. Second, this study followed children for four years through a sensitive period