Relationship between Body Composition and Gross Motor Coordination in Six-Year-Old Boys and Girls

Abstract

The aim of this study was to investigate the association between morphological characteristics (body composition and anthropometric data) and gross motor coordination in preschool children (42 boys and 40 girls, aged 6.22 ± 0.43 years, height: 1.22 ± 0.48 m, body mass index: 20.22 ± 2.34 kg/m², muscle mass: 11.50 ± 2.08 kg, and fat mass: 5.43 ± 4.02 kg). Motor coordination was determined by the obstacle course backward test (OCB), while body composition was measured using the bioelectrical impedance (BIA) method. Sex differences in the OCB test and body morphology were determined by an independent t-test. Multiple linear regression was used to examine whether morphological characteristics could predict OCB scores. Boys were significantly taller, with greater muscle mass, protein mass, and total body water compared to girls (t = 2.01–3.73, p < 0.05). Inversely, mineral mass was greater in girls than in boys (t = 2.98, p = 0.01). No significant sex differences were observed in the results obtained for the OCB test (t = 0.74, p = 0.46). All morphological variables showed trivial-to-weak (r = 0.01–0.15) associations with the OCB results, without reaching statistical significance (p ≤ 0.16). The model of predictor variables did not have a statistically significant effect on the OCB scores in boys and girls (R² = 0.09, p = 0.91 and R² = 0.012, p = 0.92, respectively). These results indicate that sex dimorphism in body composition is present at an early age before puberty, while morphological characteristics have a negligible influence on motor coordination in 6-year-old children.

1. Introduction

Gross motor coordination (MC) has been a commonly used term to describe the ability to execute accurate, smooth, and controlled body movement via harmonization of the nervous and musculoskeletal systems [1,2].

In children, MC represents a fundamental movement skill and should be regarded as an important factor of health-related fitness [3,4]. For instance, there is apparent evidence that MC strongly affects all fitness components except flexibility [5,6,7]. Moreover, previous studies [8,9,10] demonstrated that motor proficiency is an important factor underlying physical activity in children. In other words, children with a low level of MC are less prone to participate in regular physical activities compared to their motor-competent peers [8]. This is relevant given that the level of physical activity directly affects weight status; thus, a low level of MC may represent a major risk factor for obesity in children [8,11].

Interestingly, the relationship between MC and morphological characteristics has not been extensively studied in children younger than 7–8 years of age [3], although the current literature suggests that this link tends to vary according to specific age periods [1,5,12,13]. Particularly, Lopes and coworkers [1] found that the correlation between body mass index (BMI) and MC is moderately negative (r = 0.44–0.48) in 11-year-old boys and girls, yet non-significant (r = 0.16–0.18) during the preschool period. Neither Luz et al. [12] nor Kakebeeke et al. [14] observed a significant association between BMI and MC in preschool children. Still, Kakebeeke et al. [14] found that both skinfold thickness and waist circumference, rather than BMI, better predict performance in the jumping sideways test (used to evaluate MC).

Note that the majority of previous research utilized BMI as a proxy for weight status despite the fact that this method has some important fallacies, since BMI cannot discriminate between fat mass and lean body mass, and excess fat mass may conceal lean mass deficits [15,16]. In that regard, body composition assessment (i.e., muscle percent and mass, fat percent and mass, fat-free mass, percent of body water, etc.) has been advocated for as it provides additional insights about morphological status [17]. Unfortunately, although weight-related studies in adults commonly use body composition assessment, it is still an evolving field, particularly in children [16]. Only Lepes et al. [18] and Webster et al. [13] evaluated MC and some of the body composition measures in preschool boys and girls. Webster et al. [13] investigated the relationship between fundamental motor skills (locomotor and object control skills) and body composition (fat mass and percent, as well as fat-free mass) in 3–10-year-old children. They found that the 23% of variance in locomotor skills (i.e., run, gallop, hop, leap, jump, and slide) may be explained by the body composition measures, although only fat-free mass contributed significantly to the regression model. Lepes et al. [18] noted that a level of MC (evaluated by the backward movement test) strongly predicts performance in various fitness tests (for static and dynamic strength, as well as for agility), and that “general motor fitness” (expressed as the summed performance of MC, strength, agility, and flexibility tests) moderately (r = 0.47–0.57) correlate with the percent of body fat. Considering the above, it seems that body composition assessment may shed a light on the relationship between weight status and MC in preschool children. Unfortunately, the abovementioned studies [13,18] utilized motor test batteries which did not exclusively address MC and rather included several assessments of physical fitness [19]; thus, the relationship between MC and body composition in the preschool population cannot be defined.

After learning about the findings from previous research, it is clear that dimorphic differences in MC have been established at this age, but the lack of research is reflected in our knowledge on the relationship between body composition and MC in preschool children. This study should provide answers to the questions of which segments of body composition contribute the most to the performance of gross motor coordination, as well as help plan new content to be used in the field of physical education for preschool children.

This study aimed to investigate the association between body composition variables (i.e., muscle percent and mass, fat percent and mass, fat-free mass, and percent of body water) and MC in preschool children, and to identify possible sex differences in these relationships. Considering the background of the current literature regarding this topic and the only limited evidence, we hypothesized that fat content (fat percent and mass) will be negatively related to the MC performance in 6-year-old boys and girls.

2. Materials and Methods

2.1. Experimental Protocol

The experimental protocol consisted of two laboratory testing sessions, where in the first session anthropometric and body composition status were evaluated, while MC was assessed during the second session. Each session was performed in the morning hours (8–11 AM) at a constant room temperature (20–25°). All subjects were familiarized with the motor test during two pre-visits before data collection (Mandić et al., 2019) and were advised to avoid physical activity and solid food intake 2 h before the testing.

2.2. Subjects

The research was conducted at the beginning of September 2022 in Belgrade (Serbia) on a total sample of 82 preschool children (40 girls and 42 boys, 6.22 ± 0.43 years). The sample for this study was chosen randomly, and this sample size was justified by a priori power analyses using G-power software with a target correlation value (r) of 0.3, an alpha level of 0.05, and a power (1-ß) of 0.80 [20]. A non-experimental research design, or more precisely, an ex post facto research design, was used. In relation to the time duration, the transversal method was used, while in relation to the degree of control, the semi-laboratory method was applied.

All participants were free of musculoskeletal, neurological, and orthopedic disorders. Additionally, all of the participants were free from diabetes, congenital disorders, or any other metabolic syndrome conditions. Except for the regular physical education curriculum in kindergarten, the participants were not involved in any additional form of physical exercise outside their institution. Informed consent was obtained from the children’s parents/guardians prior to the experiment. Ethical approval was obtained from the Teacher Education Faculty, University of Belgrade, and all experiments were conducted in accordance with the Declaration of Helsinki.

2.3. Morphological Assessment

Body height, body mass, and body mass index (BMI) were taken as anthropometric measures. Body height was measured using Martin’s portable anthropometer (Siber-Hegner, Switzerland) with an accuracy of 0.1 cm, whereas body mass was measured with an electronic scale (Tanita, Arlington Heights, IL, USA). BMI was calculated using the standardized formula proposed by the World Health Organization. Weight status was classified according to the International Obesity Task Force (IOTF) cut-off values for BMI [21]. Body composition variables were measured with the In-Body 230 (Biospace Co., Seoul, Republic of Korea) using the direct segmental multi-frequency bioelectrical impedance analysis (DSM–BIA) method and included 8 outcome measures: skeletal muscle mass, fat-free mass, fat mass, percent of body fat, total body water, intracellular water mass, extracellular water mass, protein mass, and mineral mass. Height measurements, age, and sex were manually inserted into the BIA device. Prior to testing, the subjects were instructed not to eat anything in the morning, to avoid any kind of exercise 24 h before analysis, and to perform all physiological needs before the measurement. Subjects were in the standing position for at least 5 min prior to the measurement for the redistribution of body fluids. During the measurement, all subjects were in light sports clothing and had no metal accessories. There were no predetermining parameters to control/normalize all subjects.

2.4. Assessment of Motor Coordination

The obstacle course backward (OCB) test was used to evaluate MC. Based on the statistical and metric characteristics of the test, the Cronbach α coefficient for this test for preschool children aged 6–7 years is α = 0.961, which makes it highly reliable [22]. Previously, the OCB test was shown to be a valid and reliable tool to access MC in the preschool population and has been frequently used in previous research [7,18,23].

The OCB test was performed on all fours (supported only on the feet and palms) in a backward direction, moving as fast as possible over a 10 m distance. Two obstacles were set; first, the vaulting box cover and then the vaulting box frame (3 and 6 m from the starting line, respectively). The subject was required to overcome the first obstacle by climbing and the second by crawling. During the task, the subject was not allowed to turn his head at any moment, but to constantly look between his legs. The task was measured in the tenths of a second with appropriate intervals between each repetition [23].

2.5. Statistical Analysis

The Shapiro–Wilk and Levene tests were used to assess the normality of the distribution and the homogeneity of variances, respectively. The independent samples t-test was used to determine the differences between boys and girls in tested variables. Pearson’s moment correlation was used to examine the association between morphological variables and the OCB test results. According to Hopkins, Marshall, Batterham, and Hanin [24], the r coefficients were classified as trivial (0.00–0.09), small (0.10–0.29), moderate (0.30–0.49), large (0.50–0.69), very large (0.70–0.89), nearly perfect (0.90–0.99), and perfect (1.00). Multiple linear regression was used to assess how well the morphological factors could predict OCB scores. Statistical analysis was performed using the IBM SPSS Statistics software package (Version 21, SPSS Inc., Chicago, IL, USA). All data are presented as mean ± SD, where p ≤ 0.05 is considered a statistically significant determinant.

3. Results

With respect to the whole sample of the study, 75% (n = 72) of the participants could be classified as normal weight and 20% (n = 19) as underweight. Only 5% (n = 5) could be classified as overweight, and there were no obese participants. Sample descriptive statistics for the tested variables are presented in

Table 1. Descriptive statistics of variables.

Variables	Mean ± SD
Age (years)	6.22 ± 0.43
Obstacle course backwards (s)	184.02 ± 46.06
Skeletal muscle mass (kg)	11.50 ± 2.08
Body fat mass (kg)	5.43 ± 4.02
Total water (kg)	16.92 ± 2.61
Intracellular water mass (kg)	9.89 ± 1.34
Extracellular water mass (kg)	6.13 ± 0.84
Protein mass (kg)	4.26 ± 0.60
Mineral mass (kg)	1.61 ± 0.25
Fat-free mass (kg)	22.46 ± 2.74
Body height (m)	1.22 ± 4.85
Body weight (kg)	24.67 ± 3.11
Body mass index (kg/m2)	20.22 ± 2.34

.

Significant sex differences were noted in six morphological variables; boys were significantly taller (by 0.34 ± 0.01 m, p = 0.01), with greater muscle mass (by 1.08 ± 0.42 kg, p = 0.01), protein mass (by 0.24 ± 0.12 kg, p = 0.01), total body water (by 1.10 ± 0.42 kg, p = 0.04), and extracellular water mass (by 0.42 ± 0.17 kg, p = 0.02) compared to girls. Inversely, mineral mass was greater in girls than in boys (by 0.14 ± 0.05 kg, p = 0.01). On the other hand, no significant gender differences were observed in the OCB test (p = 0.46) (

Table 2. Sex differences in morphological variables and coordination.

Variables	Boysn = 42	Girlsn = 40	t	p
Obstacle course backwards (s)	187.21 ± 50.13	180.25 ± 40.99	0.74	0.46
Skeletal muscle mass (kg)	11.99 ± 2.01	10.92 ± 2.03	2.60	0.01
Body fat mass (kg)	5.92 ± 4.67	4.86 ± 3.05	1.29	0.20
Total water (kg)	17.42 ± 2.51	16.32 ± 2.63	2.10	0.04
Intracellular water mass (kg)	10.13 ± 1.39	9.61 ± 1.23	1.93	0.06
Extracellular water mass (kg)	6.32 ± 0.87	5.90 ± 0.76	2.49	0.02
Protein mass (kg)	4.37 ± 0.60	4.13 ± 0.57	2.01	0.05
Mineral mass (kg)	1.54 ± 0.22	1.69 ± 0.25	−2.98	0.01
Fat-free mass (kg)	22.37 ± 3.04	22.57 ± 2.34	−0.36	0.72
Body height (m)	1.24 ± 0.39	1.20± 0.52	3.73	0.01
Body weight (kg)	24.61 ± 2.63	24.79 ± 3.63	−0.35	0.72
Body mass index (kg/m2)	19.89 ± 2.05	20.62 ± 2.60	−1.50	0.14

).

Morphological variables showed trivial-to-weak (r = 0.01–0.15) associations with the OCB scores, without reaching statistical significance (p ≤ 0.16). Particularly, body weight and protein mass showed a small correlation (r = 0.13–0.15, p ≥ 0.16) with the OCB test. Additionally, a small correlation (r = 0.10–0.11, p ≥ 0.22) was observed between the OCB test and the intracellular and extracellular water mass, but only in girls. All other morphological variables showed a trivial (r = 0.01–0.05, p ≥ 0.38) association with the OCB test. Accordingly, a system of predictor variables did not have a statistically significant effect on the criterion variable (i.e., OCB) in boys and girls (F = 0.43, R² = 0.09, p = 0.91 and F = 0.42, R² = 0.12, p = 0.92, respectively). The multiple correlation coefficient in boys was R = 0.29 and R = 0.34 in girls. The percentage of shared variability between the system of predictor variables and the examined criterion was slightly higher in girls (12%) than in boys (9%). Based on the standardized regression coefficient, it can be concluded that none of the predictor variables had a statistically significant influence on the criterion variable of OCB (pbeta ≤ 0.15) in both groups of participants (

Table 3. Relationship betwen morphological characteristics and coordination.

Variables	Boys				Girls
	r	p	Beta	pbeta	r	p	Beta	pbeta
Skeletal muscle mass	−0.02	0.45	0.56	0.85	0.01	0.50	−0.27	0.60
Body fat mass	0.10	0.23	0.22	0.31	−0.05	0.38	0.01	0.98
Total water	−0.02	0.45	−0.62	0.84	0.04	0.39	0.29	0.56
Intracellular water mass	0.01	0.49	2.22	0.33	0.10	0.26	−0.56	0.65
Extracellular water mass	−0.03	0.43	−2.81	0.15	0.11	0.25	0.91	0.49
Protein mass	0.01	0.19	0.10	0.95	0.13	0.21	0.13	0.56
Mineral mass	−0.04	0.41	0.54	0.37	−0.03	0.43	−0.36	0.24
Fat-Free mass	−0.01	0.48	−3.07	0.90	−0.02	0.45	−0.01	0.98
Body height	−0.04	0.39	−0.04	0.82	0.03	0.43	−0.24	0.32
Body weight	−0.11	0.22	−0.01	0.97	0.15	0.16	0.28	0.21
	R = 0.29				R = 0.34
	R2 = 0.09				R2 = 0.12
	R2 = 0.11				R2 = 0.15
	p = 0.91				p = 0.92

).

4. Discussion

The study was conducted with the aim to investigate whether body composition status affects MC performance in preschool boys and girls. The main results revealed that: (i) there are no sex differences regarding motor competence, but certain dissimilarities still exist for body composition parameters, and (ii) performance in the MC test is not related to the body composition variables in preschool boys and girls.

In the present study, we found no significant differences between 6-year-old boys and girls in regard to MC test scores. Similar findings were reported by previous research studies [13,25,26], indicating that there are no sex differences in MC competence at preschool age.

This phenomenon should be viewed from several sides. Namely, in this age period, coordination should be treated as a general motor factor that is still largely under the mechanism of structuring movement [27,28,29,30,31]. This, among other things, depends on how quickly a person can form their own motor programs, i.e., at what speed they can adopt new movement structures. The general character of the motor behavior of preschool children can be explained by their areas of the cerebral cortex, which are not fully functionally formed at this age; instead of causing specific functional activities to occur in the central nervous system (CNS), the entire functioning of the cerebral cortex occurs. To fully understand this, it is necessary to understand the cerebral cortex. During the learning of a motor task through the feedback system, which includes receptors in the muscles, kinesthetic receptors for movements in the joints, and those that react to changes in balance, a process of regulation takes place. The more difficult the performance of a motor task, the more regulation is needed, and the easier it is to perform after a greater number of repetitions where only the management process is needed [32]. Much earlier research conducted by Reitmeier and Proje [33] indicates better motor competence (coordination) in boys at this age. That trend continued later, as was found in research by Bala and Cvetković et al. [27,28,30] that also indicated a better coordination of the whole body in boys. If we look at the obtained results from the point of view of children’s needs in the past, we could explain the phenomenon by the different needs of boys for movement, which were usually more dynamic in nature compared to girls. A higher level of strength mastery and the presence of explosive movements earlier in their activities led to a better development of basic motor skills, which has been implied to improve their dexterity, or better said, the mechanism for structuring movement, which manifests itself in coordination. Today, this is not the case due to the large presence of disturbing and uncontrolled factors in children’s development, such as mobile phones and various computer games, among others, to which boys are more prone than girls, and thus the differences in motor competence today has been reduced to a minimum or does not exist.

Conversely, with respect to body composition, several dissimilarities between boys and girls were observed in this study. Specifically, boys were taller, with greater muscle and protein mass, and total body water levels. Inversely, greater mineral mass was observed in girls. Previously, it was postulated that sex differences in body composition at the preschool age should be considered negligible [34], preferentially due to the fact that marked differences in sex hormone levels do not occur before puberty [35]. However, this theory has been contested since recent studies noted significant sex differences in lean muscle mass, even at the ages of 3 and 10 years old [13,35,36,37]. Particularly, both Kirchengast [35] and Webster et al. [13] found that 6-year-old boys have about 5% greater muscle mass than female peers, which corresponds well with our results (Table 1). Thus, our findings further support the idea that sex dimorphism is present at an early age, before puberty [13,35], and that other factors besides sex hormone accretion may be responsible for sex differences in body composition.

Contrary to our hypothesis, the present results revealed that neither body composition nor BMI was significantly related to the scores obtained on the OCB test, suggesting that morphological features have a negligible influence on MC. Concerning BMI, our findings are consistent with previous studies [1,12,14] in which BMI did not correlate with MC in 6-year-old children. On the other hand, our results do not support previous reports [13,14,38] that body composition status significantly affects MC (and vice versa) in children. The possible reason for these discrepancies may be twofold, being related to the sample characteristics and methodological approach to evaluate MC.

In the current study, the sample included less than 5% of excessive-weight (overweight and obese; based on BMI) children, whereas in other studies [13,14,38] the percentage of excessive-weighted children was quite larger (i.e., 15–20%). This is relevant, since a low level of motor competence may indirectly affect obesity status in children through reduced physical activity [8,11]. Hence, it is quite possible that a link between some morphological factors (BMI, skinfold thickness, body fat mass, etc.) and MC may be present in the overweight and obese population; however, this association is not apparent in normal and underweight children, as our results suggest. Moreover, note that the MC is a multidimensional construct and there are different aspects of MC (i.e., coordination in rhythm, speed performance in complex motor tasks, etc.), which can be assessed by various motor tests [2,39]. For instance, Webster et al. [13] utilized the Test of Gross Motor Development (TGMD), which includes skills such as running, jumping, sliding, etc. Although this test primarily evaluates MC, it is partially related to physical fitness (presumably strength and agility) [19]; hence, it is not surprising why [13] identified muscle mass as an important predictor of TGMD scores. In the current study, we applied the OCB test, which is a reliable tool for assessing MC through movement structure factors [22,40] and requires a significant level of perceptual skills [40] since the motion is performed in a backward direction and also includes movements such as climbing and crawling. Thus, although the OCB test requires body mass propulsion (i.e., the movement of a larger mass against gravity), this type of test probably relies on cognitive potential rather than morphological factors, which might explain the absence of the correlation between MC and morphological features in the current study. We are aware that this study is not without limitations. First, this was a cross-sectional research study; therefore, direct causality between variables cannot be determined. Second, this study used BIA, which is a valid and reliable tool for the estimation of body composition, but still has some constraints. The third limitation of the present study is the small number of children who were classified as obese. Finally, we used only one specific test to assess MC, which is the main limitation of the study. In this context, further research is warranted to clarify whether different aspects of MC may be related to body composition in preschool children.

5. Conclusions

Few studies have utilized body composition assessment in the preschool population. The present results demonstrated that 6-year-old boys have significantly greater muscle mass than their female peers, while the level of MC seems to be similar between sexes. Boys are also slightly shorter and have slightly higher body fat values, which may somewhat indicate a faster entry of girls into the intensive phase of growth because the cells are filled with fat before that phase. Therefore, it is assumed that the girls have already passed that period, and for a few months the longitudinal dimensionality of the skeleton could dominate the growth of the bones in length. Body composition and BMI have a negligible influence on MC in both sexes, suggesting that other aspects that are probably related to cognitive potential may be important factors underlying MC in preschool children.