Effects of Overweight/Obesity on Motor Performance in Children: A Systematic Review

Childhood obesity is a serious public health problem. Childhood obesity and overweight are associated with the appearance of coordination deficit disorder and can cause impaired motor performance. We searched online databases for all related articles using comprehensive international databases from the Medline PubMed Institute, Web of Science, ScienceDirect, SCOPUS, and PsycINFO up to December 20, 2020. Overall, 33 studies were included in this systematic review. The present review demonstrated that children with higher percentage of body fat had lower levels of moderate to vigorous physical activity, as well as decreased levels of gross motor coordination, as shown by tests for neuromuscular performance. These results corroborate the hypothesis that overweight and obesity in children and adolescents are associated, not only with insufficient performance during gross motor coordination activities, but also with a greater risk to physical health. Systematic Review Registration [https://www.crd.york.ac.uk/prospero/], identifier [CRD42020182935].


INTRODUCTION
Childhood overweight and obesity are one of the greatest public health challenges worldwide. The World Health Organization estimates that approximately 70 million children will be overweight or obese by 2025, as children below 5 years old have shown a rapid increase in the development of overweight and obesity in recent years (1). Childhood is a critical period for the development of overweight and obesity. Increased consumption of unhealthy sugar, sodium, and fats, in addition to ultra-processed foods, including sugar-sweetened beverages and high-energy, nutrient-poor packaged foods have been strongly associated with weight gain and several nutrition-related non-communicable diseases (2). The high rate of obesity is associated with an increase in the development of some disease conditions such as systemic arterial hypertension (3), insulin resistance (4), and stroke (5). In addition to these conditions, obesity can affect physical parameters such as motor performance and gross motor coordination, as they seem to be directly related to regular physical activity and body composition in children and adolescents (6).
Motor coordination corresponds to the congruous interactions between the nervous, skeletal, and sensory muscle systems, in order to produce precise motor actions, in addition to quick reactions to everyday situations, which involves proper development of muscle strength and the proper selection of muscles that control the performance of the movement (7). Notably, motor performance in childhood and adolescence may be related to the programming of physiological systems in adult life (8,9).
Motor competence, on the other hand, is the ability to perform different motor actions, including coordination and gross motor skills (10). Gross motor competence is often defined as proficiency in a range of fundamental movement skills such as throwing, catching, and running, which are normally learned during preschool and early school years (11,12). These provide a basis for children to develop more in specialized movement sequences, such those required in sports activities (13).
A growing body of studies have investigated the possible relationship between gross motor coordination and the level of adherence to participation in physical activity during adolescence. Most studies found a positive association between better performance in gross motor coordination and participation in physical activities (14,15).
It is possible that children and adolescents with poor gross motor skills may not want to participate in physical activity, because it can be more challenging for. It is also plausible that among children with poor gross motor skills, sedentary activities (i.e., watching TV and computing games) may be more enjoyable options.
The muscle is characterized by plasticity and, therefore, is more likely to change its structure and function. In animals, accumulation of intramuscular fat caused stiffness in the muscle tissue, which caused less contractility and decreased strength in the gastrocnemius muscle (16). In humans, a longitudinal study carried out on growth and physical fitness related to health and motor competence in elementary school children showed that the pathways for the development of physical and motor fitness are related to the children's body weight. Children who had a low or medium rate of development of physical fitness and motor competence were more likely to develop overweight or obesity at the end of primary school, regardless of sex and body mass index at baseline (17).
In this context, it is necessary to clarify how environmental factors can influence the appearance of overweight and obesity; in addition, it is necessary to understand the relationship between overweight and obesity and motor performance in childhood (18)(19)(20). Core motor tasks include bilateral and upper limb coordination, strength, balance, speed, and running agility.
Motor skills are acquired from the physiological maturation of the neuromuscular system and environmental factors (21) and correspond to a group of coordinated movements that children begin to learn during early childhood and involve locomotor skills and object control. Locomotor skills are used to move the body through space, such as running, galloping, and jumping. The object control task is the ability to manipulate and project objects such as throwing, catching, dribbling, kicking, hitting, and rolling (22).
Although the genetic and biological determinants of obesity can interact throughout life, the process that regulates the developmental trajectories of other potentially important behavioral factors linked to the status of body weight has not been investigated.
Another aspect to be noted is that few studies have explored the contribution of current body composition to motor performance of the research participants. Understanding the relationship between overweight and obesity and children's physical activity can guide the development of interventions at different levels that may provide a better chance of increasing the levels of physical activity in the population. Therefore, the objectives of this study were to analyze the influence of overweight and/or obesity on motor performance and gross motor coordination in children and adolescents.

METHODS AND MATERIALS
The protocol for this systematic review been published online (https://www.crd.york.ac.uk/prospero/) in PROSPERO (registration number CRD42020182935) and was reported as per Preferred Reporting Items for Systematic Reviews and Metaanalysis (PRISMA) (12). less than 30 individuals. No language or period of publication was set. However, a search filter was activated for viewing studies performed only in humans. The following PICOS criteria were established: Population: children and adolescents; Intervention/ exposure: motor training; Comparison: between sexes; Results: overweight/obesity, motor coordination; Study design: crosssectional and longitudinal studies. Initially, the studies were pre-selected according to titles and abstracts. In the next stage of the study selection phase and after excluding duplicate articles, texts considered eligible were read in their entirety.
Data were collected from the selected studies based on the characteristics of the studies, the results, and the components used to assess the intervening factors were verified. For the qualitative synthesis of the data, the following characteristics of the studies were used: author's name, year of publication, country, age variation, sex, nutritional status, total population, analyzed variables, body composition, and motor performance results.

Data Extraction
Selected abstracts were submitted to the second stage of analysis, in which two independent researchers reviewed the articles completely and, by consensus, excluded articles that did not meet the criteria. The following data from eligible articles were extracted: characteristics of the sample (mean age, distribution between sexes, and nutritional status), materials and methods (analyzed variables), and the main results found related to body composition and motor performance. The data extracted from the articles were collected using a standardized method among the authors. It was not possible to perform a meta-analysis in the present study, since there was substantial sample heterogeneity, in addition to the variability in the age range of the population of the studies, which could hinder the reliability of a meta-analysis.

Risk of Bias
The risk of bias was established through of a critical analysis of the studies selected using seven criteria for a methodological judgment supplied by the software Revman 5.3.0 program the Cochrane Handbook 23, developed for systematic reviews and available for free download (https://training.cochrane.org/online-learning/coresoftware-cochrane-reviews/revman/revman-5-download). Among the criteria that structure the bias assessment are (1) random sequence generation, (2) allocation concealment, (3) blinding of participants and personnel, (4) blinding of outcome assessment, (5) incomplete outcome data, (6) selective reporting, and (7) other bias.

Study Selection
A total of 388 studies were identified in the literature search. Two duplicates were found. Of these 386 studies, 38 met the inclusion criteria based on the title and abstract. Finally, 33 studies ( Figure 1) were included in this review.

Risk of Assessment
No studies with low risk of bias were excluded. The results are shown in Figures 2 and 3.

Nutritional Status and Age Group
The classification of the relationship between nutritional status and age group was heterogeneous among the selected articles. An article that included children between 5 and 7 years old found that most participants had normal nutritional status (23). In children between 7 and 14 years old, two articles reported an inverse association between BMI and motor coordination (27). In another article, children who ate breakfast almost every day had better functional motor skills and a lower BMI than children who did not eat breakfast regularly (38). Overweight was more prevalent in three articles (20,24,32), overweight and obesity in three articles (33,35,40), normal and overweight in one article (34), normal and obesity in one article (37), and obesity in one article (30), and in most studies, participants were classified as having normal weight (25,26,28,31,36,39). In children between 6 and 10 years old, our analysis revealed a higher prevalence of normal weight (41,(44)(45)(46), while in two studies, children were classified as overweight and obesity (42,43). Other articles had a different age range from those already presented. A study of children 5 and 10 years old found that 21.7% of children had obesity at 5 years, and at 10 years old, 22.9% were overweight (47). Another study with children 5-12.8 years old found that the majority of the population studied was eutrophic (50), whereas in another, the majority had overweight and obesity (47); in one study, 1,526 out of 5,138 children evaluated had high BMI (48).
This systematic review investigated the characteristics of body composition and motor performance in children, without orthopedic or neurological changes, notably related to gross motor coordination with or without exposure to physical activity. The results of analysis, specifically the main characteristics of the included studies, were organized according to the correlation between body composition and motor performance ( Table 1).

Body Composition Related to the Motor Performance of Children and Adolescents
Based on the theory of developmental plasticity, overweight and/ or obesity in children and adolescents can interfere with motor performance, alter postural control, and, consequently, modify the state of motor coordination of these individuals. Taking this into account, six included studies assessed the research participants' motor performance using running speed and agility tests such as the six-minute running test, TUDS (timed ascent and descent test), and other explosion tests (28,34,35,37,43,54). In one of these studies, the authors found a relationship between an increase in the percentage of body fat and a decrease in the levels of moderate to vigorous physical activity (43).
Another study observed a decrease in the levels of static strength and explosive power in girls 7-11 years old with obesity, as well as in boys 10-11 years old with obesity (54). Balance and muscle strength power represent important components related to the ability of physical fitness that have to be sufficiently developed throughout life to perform sports and daily activities to decrease the risk of injuries and falls (56). Furthermore, Tsiros et al. (28) found a decrease in motor performance in children with obesity during the TUG (timed up and go), 6MWT (sixminute walk test), and TUDS tests. Other studies found that using explosion motor performance tests, overweight children had worse performance in the long jump and 10-and 20-m sprints; in addition, individuals with an increased percentage of body fat showed lower indexes in the long jump and repetition during sit-ups, in addition to a deficit in perceived physical capacity (34,35).
Prevalence of overweight and obesity associated with the levels of physical fitness among primary school age children in Assiut city CPA (Checklist of Psychomotor Activities), KTK (Body coordination test for children: Koërper Koordination Test für Kinder), MABC (Movement Assessment Battery Test for Children), and BOTMP-SF (Bruininks-Oseretsky Test of Motor Proficiency-Short Form) was investigated. Three studies used MABC to assess global motor coordination and balance (26,31,50) in a population of 540, 2,029, and 2,057 children, respectively. Another four found a greater propensity to develop deficit of coordination in children with greater accumulation of body fat, BMI, and obesity, successively (32,42,47,53). However, most studies used KTK to assess gross motor coordination.
In this review, worse performance of gross motor coordination in children with obesity was observed (27, 41, 44-46, 48, 49, 55). One study investigated only the participants' balance and found a decrease in balance skills with increasing body mass (52). Furthermore, overweight was negatively associated with lower overall performance of   (24), while children with obesity had mild motor difficulties (20); overweight and obesity were related to less perceived and real physical competence (33), in addition to lower performance in side jumping, standing long jump, 20-m speed back-and-forth running (38), and decreased motor skills (40). Notably, a study including 380 children revealed that the association between nutritional status and motor classification in boys and girls was not significant, which, according to the authors, neutralizes any influence of nutritional status on motor classification (39) ( Table 2).

DISCUSSION
Overall, the results of this review confirmed the hypothesis that overweight and obesity can negatively affect motor performance and gross motor coordination in children and adolescents, although age, nutritional status, and the measures of motor performance analyzed were different among the investigated studies.
It is well recognized that motor performance in some tests is negatively affected by higher body weight (23,53). In analyzing the magnitude of the relationships between gross motor coordination, physical activity, and physical conditioning, weight was strongly associated with age and sex in gross motor coordination tests (57,58). A meta-analysis showed that age was positively associated with locomotion, object control, and stability skills. It is not surprising that the older children are, the better their skills, as long as they continue to participate in activities that develop these skills. Motor development in young children is influenced by biological maturation, and after this period, it depends more on practice and opportunity. Thus, it is conceivable that the relationship between age and gross motor competence may change over the developmental periods of early childhood, preschool, childhood, and adolescence. Notably, although primary evidence confirms age as a positive correlate in most aspects of motor competence, some studies (across all types of motor competence) have not found this relationship (59). One study that found age to be a negative correlate involved     adolescents and suggested that the decline in girls' motor competence was due to a reduction in the opportunity to be active (60). It then appears that gross motor coordination improves with age during middle childhood and adolescence, although there is a lack of consensus on sex-related differences between age groups and the gross motor coordination tests used.
In contrast to object control-related skills, which tend to be more static, locomotor activities involve changing or controlling a larger body mass that impedes functional movement and contributes to a higher rate of lower limb orthopedic changes, such as tibia rod and plantar pressure, among children with obesity (61). The negative association between gross motor activity and higher BMI may reflect the composition of assessments where the compound requires better motor coordination while moving and controlling the body, compared to object control skills. Sex, on the other hand, seems to relate differently to various aspects of gross motor competence. Male sex was considered a strong positive correlate of object control and motor coordination tasks, with prematuration biological differences being considered for boys and girls, especially in reference to skills such as throwing (62). Research has shown that, compared to girls, boys receive greater encouragement, support, and opportunities to engage in physical activity and sports at home and at school. Thus, girls' opportunities to improve their gross motor skills may be limited (63,64).
Biological and environmental factors can influence motor coordination, favoring both boys and girls. The activities performed by different sexes facilitate the performance in certain items of motor coordination; therefore, sex can be an intervening factor in motor performance. Regarding overweight and obesity, one of the hypotheses that can explain the interference in the performance related to gross motor coordination tasks is that during the tasks of supporting the body weight, there is a higher proportion of fat mass that must be supported or moved against the action of the force of gravity (65).
Another factor that can interfere with the performance in motor coordination is time, as can be seen in a longitudinal study that investigated the relationship between children's weight and the level of gross motor coordination over time. Baseline measurements were collected from 2,517 children (5 to 13 years old, 52.8% boys). Measurements included the following: height and body weight for the calculation of BMI and gross motor coordination through KTK. After 2 years, 754 participants (7 to 13 years old, 50.8% boys) underwent anthropometric and KTK assessments again. There was a positive relationship between the worst motor performance at KTK at baseline and an increase in BMI. In addition, a higher baseline BMI score also predicted a decrease in KTK performance, suggesting that children's weight negatively influences the level of gross motor coordination in the future and vice versa. Therefore, prevention and intervention initiatives through physical activity must consider this reciprocal causal relationship over the development time (50).
Furthermore, physical activity has a potential protective effect against the development of metabolic diseases during childhood and reduces the prevalence of cardiovascular diseases and diabetes, and morbidity and mortality of adult individuals prematurely (66). Thus, regular physical activity and adequate nutrition during the years of child growth and development increases the possibility of a healthy pattern of physical maturation consistent with a child's genetic potential (67). Dudas et al. (2008) found that overweight children showed lower participation in sports clubs, while even more children with healthy weight were able to ride a bicycle.
In this perspective, this review demonstrated that children with a higher percentage of body fat had lower levels of moderate to vigorous physical activity, as shown by the neuromuscular performance in running and long jump tests (43). In addition, Tsiros et al. (28) performed a study on 239 children, of whom 107 had obesity and 132 had a healthy weight. They observed restrictions in the group with obesity regarding the ability to perform TUG, 6MWT, and TUDS. Morano   reported less perceived and real physical competence, a higher index of perceived body fat, and body dissatisfaction. Eutrophic childhood, on the other hand, showed better performance in standing long jump, shuttle run, and 20-m and 30-m run.
It is important to note that the mechanisms involving the neuroendocrine and musculoskeletal systems interact with each other and can explain the associations between weight and performance in gross motor coordination tests. Scientific literature demonstrates that stimuli from greater muscle activity are capable of promoting in their microenvironment the synthesis of chemical compounds called myokines. Among these, BDNF (brain-derived neurotrophic factor) and, recently, irisin stand out, because they are able to overcome the bloodbrain barrier and can promote a positive outcome in both the cognitive and motor domains (68,69).
For several years, muscles were considered targets for hormonal action; however, there is growing evidence that muscles, in a retrograde manner, exert unique forms of control over the CNS that affect motor behavior. Therefore, increasing evidence indicates that neural and muscular systems maintain some degree of plasticity throughout life, demonstrating that environmental factors influence the development of the musculoskeletal system and, as a consequence, motor performance.

CONCLUSION
Our results corroborate the hypothesis that overweight and, especially, obesity in children and adolescents are associated not only with insufficient performance during gross motor coordination activities, but also with an increased risk to physical health. It is, therefore, necessary to prevent childhood obesity and reduce the weight of affected children, and promote healthy eating and physical activities in daycare centers, schools, and homes. To be effective, in addition to the educational sector, all sectors of society must be mobilized so that the negative effect of commercial food products on children's diets will be reduced.

DATA AVAILABILITY STATEMENT
The original contributions presented in the study are included in the article/supplementary material. Further inquiries can be directed to the corresponding author.

AUTHOR CONTRIBUTIONS
WB and MSF contributed to research conception, data collection, interpretation of results, and critical review of the article. RS, KS, ASS, MS, and AS contributed to data analysis and interpretation, drafting, and critical review of the article. SS and VO contributed to data collection and critical review of the article. All authors contributed to the article and approved the submitted version.