1. Introduction
dolescence is defined as the period of developmental processes of transition from childhood to adulthood. One of the aspects of adolescence is the physical and psychological changes of puberty from the beginning of this period. At this stage of puberty, a person’s skeletal condition is affected for various reasons, which can also affect the person’s balance somehow. Musculoskeletal abnormalities affect posture and stability. Maintaining balance and postural control is one of the essential tasks of the human locomotor system. From a biomechanical point of view, the foot is a functional unit that aims to maintain body weight and provide leverage to move forward when walking and running.
Biomechanical changes in the base of support and disruption of different information of any joint or structure located along the lower extremity motor chain can affect postural control strategy [1]. Despite their small surface area, the soles play an important role in maintaining the body’s balance. The anatomical structure of transverse, internal longitudinal, and external longitudinal arches cause the formation of stable operations and the production of force to move the body forward in all human activities [2]. 
Due to the determining role of balance factor in the process of growth and motor development in childhood and adolescence, the effect of deformity or structural deformities of the foot on maintaining body balance during this period has not been studied by researchers. Since providing treatment and correction programs for plantar deformities in childhood and adolescence is more effective, it is more important to address this issue. This study aimed to compare the ‘plantar arch index’, ‘weight distribution’, ‘equilibrium performance’, and selected ‘musculoskeletal disorders’ in the active and non-active adolescents.
2. Materials and Methods
This is a quasi-experimental and descriptive study. The statistical population consisted of adolescents in Tehran City who were randomly selected. The statistical sample included 50 persons with the age range of 11-14 years, among which 25 subjects with the Mean±SD age of 12.46±1.10 years, the Mean±SD height of 157.69±8.48 cm, and the Mean±SD weight of 46.65±8.45 kg were located in the “non-active” group, and 25 others with Mean±SD age of 12.26±1.13 years, the Mean±SD height of 153.91±10.09 cm, and the Mean±SD weight of 44.52±7.76 kg were located in the “active” group. 
To evaluate the normality of data distribution, the Kolmogorov-Smirnov test was used. Spearman’s correlation and Mann–Whitney U test were used to assess the relationships between variables at a significance level of 0.05. All subjects were healthy at the time of the study, and they completed a personal satisfaction questionnaire to participate in the study. The test procedure was described in detail for each subject. Subjects’ skeletal abnormalities were first assessed manually by the New York test. Based on this test and using the visual method using a checkerboard, different parts of the body were evaluated, and then the results were recorded in a particular table.
To evaluate the feet’ soles, first, the observational method was used. Using the American-made 3BODY VIEW foot scanner, the subjects’ type of complication and INDEX were determined. Also, to measure the dynamic balance, an ENC device made by “Danesh Salar Iranian Co”. was used.
3. Results
The independent t-test revealed that the two groups had a significant difference in equilibrium performance (P=0.04), but there was no significant difference in weight distribution parameters. Also, the Mann-Whitney test results did not reveal a significant difference between the two groups in the variables of the ‘plantar arch index’ and ‘musculoskeletal abnormalities’ (P<0.05). 
As you can see in Table 1, the dynamic balance had a significant difference (P=0.04) only in the “forward head” complication of the “non-active” group. 


“Pronation” anomaly had a positive correlation with “forward head” complication, and a significant level (P=0.03) was observed, but “supination” anomaly was negatively correlated with “forward head” complication in the “active” group and positively correlated with the “non-active” group; however, no significant level was observed. 
The arch of the sole of the foot with dynamic balance and weight distribution on the left foot, supination and varus has a negative correlation in the active group; Also in the inactive group, this negative correlation is observed only in the weight distribution on the left foot and supination. Besides, there was a significant difference between the “plantar arch index” with “active” group “pronation” (P=0.01) and “active” group “varus” (P=0.05) and “active” group “valgus” (P=0.05) as well as “non-active” group “pronation” (P=0.01). “Dynamic balance” in the “active” group had a negative correlation in “weight distribution” on the right foot, “pronation,” “varus,” and “valgus”.
“Kyphosis” negatively correlated with other lower limb abnormalities, but no significant difference was observed. The correlation between “varus” and “valgus” was also negative in both “active” and “non-active” groups, with only a significant difference in the “active” group (P=0.00).
4. Discussion and Conclusion
The ability to maintain postural control is an essential factor in performing many daily activities. Motor skills play a significant role in children’s learning and provide a basis for developing other critical understandings such as academic and social skills. As a result, any disruption in the motor skills process can lead to weakness and difficulty in academic, social, individual, and learning skills in adolescents. The results of this study revealed that in the variables of “plantar arch index” with selected upper limb abnormalities, no difference was observed between the “active” and “non-active” groups.
“Lordosis” had a negative correlation with other upper limb abnormalities in the “active” group. The “plantar arch index” with “dynamic balance” and “weight distribution” on “supination” and “varus” had a negative correlation in the “active” group. Still, in the “non-active” group, this negative correlation was observed only in the “weight distribution” on the “supination”. “Kyphosis” was also negatively correlated with other lower limb abnormalities. 
This study revealed the difference between dynamic balance and musculoskeletal abnormalities in active and non-active adolescents. However, many factors affect the ankle’s posture and structure during activity and balance function, causing impaired balance, decreased stability, the prevalence of skeletal abnormalities, and reduced performance. To test these hypotheses requires more extensive research with more sophisticated equipment.

Ethical Considerations
Compliance with ethical guidelines
All ethical principles are considered in this article. The participants were informed of the purpose of the research and its implementation stages. They were also assured about the confidentiality of their information and were free to leave the study whenever they wished, and if desired, the research results would be available to them.

Funding
This research did not receive any grant from funding agencies in the public, commercial, or non-profit sectors

Authors' contributions
All authors equally contributed to preparing this article.

Conflicts of interest
The authors declared no conflict of interest.


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