EFFECTS OF OBESITY ON POSTURAL BALANCE IN CHILDREN AGED 7 TO 13 YEARS
REGISTRO DOI: 10.5281/zenodo.10020215
Maike Mergulhão Dias1
Andreo Fernando Aguiar2
Ana Paula do Nascimento3
Juliano Casonatto4
Rafael Cavallari Pasqualinotti5
Rubens Alexandre da Silva Junior6
Fabiana Dias Antunes7
Eros de Oliveira Junior*8
Resumo
Childhood obesity has been increasing significantly and few studies have investigated the impact of this condition on postural balance. This study aimed to verify the influence of childhood obesity on static postural balance. Thirty children of both sexes aged between 7 and 13 years were divided into two groups: obese group (N =15) and non-obese control group (N =15). Static postural balance was evaluated using a force platform in 2 situations: 1) in the bipedal stance test for 60 seg., and 2) in the unipedal stance test for 30s. The average of 3 trials for each test was used for statistical calculations. The following variables were analyzed: center of pressure (COP) ellipse area (in cm2), mean velocity of COP oscillations (in cm/s), and mean frequency of COP oscillations (in Hz) in the anteroposterior (AP) and mediolateral (ML) movement directions. For both the bipedal and unipedal stance tests, the non-obese control group showed better results than the obese group in terms of AP and ML velocity and frequency. In addition, there were moderate correlations between BMI and AP and ML velocities and a strong correlation for AP and ML frequency for the bipedal stance test. For the unipedal stance test, there were moderate correlations between BMI and AP velocity, and AP and ML frequency. In conclusion, obese children have worse postural balance compared to their non-obese peers, presumably due to the restrictions applied by excess weight on the control of the anteroposterior and mediolateral displacement of the body.
Keywords: Postural balance . obesity . children . childhood . center of pressure.
1 INTRODUCTION
It is estimated that overweight and obesity affect around 40 million children under 5 years of age and 340 million children and adolescents aged 5 to 19 years worldwide (NCD, 2017). In Brazil, 9.4% of girls and 12.4% of boys are considered obese, according to the criteria adopted by the World Health Organization (WHO) to classify childhood obesity (EDUCAÇÃO., 2018). Obesity can generate serious psychological, cardiac, respiratory, and musculoskeletal changes, which act in favor of degradation of the individual’s general condition, in addition to increasing the tension exerted on the joints and increasing the risk of falls and fractures (GOULDING; TAYLOR; JONES; MCAULEY et al., 2000). Furthermore, being overweight leads to a lack of physical conditioning, loss of autonomy, and even social isolation (VOLERY; CARRARD; ROUGET; ARCHINARD et al., 2006).
During static or dynamic posture, the human body uses postural strategies to maintain balance through neuromuscular postural adjustments to preserve the body’s center of mass within the base of support (POLLOCK; DURWARD; ROWE; PAUL, 2000; WINTER, 1995). Postural instability characterized by increased body weight could affect the systems involved in the integration of postural control. Obesity alters the mechanics of body mass, which undergoes movements and must be stabilized during postural balance and daily motor activities (COLNÉ; FRELUT; PÉRÈS; THOUMIE, 2008). It has been shown that obese children walk more slowly and that they spend more time in the double support phase during the gait cycle (HILLS; PARKER, 1991). Body weight then became a strong predictor of postural stability, and weight loss seems to be directly linked to an improvement in postural control and gait (HUE; SIMONEAU; MARCOTTE; BERRIGAN et al., 2007).
It is common agreement that childhood obesity has been increasing significantly (MELLO; LUFT; MEYER, 2004), however, few studies are directed to the consequences of excess weight on postural balance. Studies with obese children and adults have mainly observed a change in temporal parameters, such as speed, cadence, and duration in different phases during the gait cycle (BENEDETTI; DI GIOIA; CONTI; BERTI et al., 2009; DEVITA; HORTOBÁGYI, 2003; KO; STENHOLM; FERRUCCI, 2010). To increase knowledge regarding the functional impacts of childhood obesity, this study aimed to evaluate postural balance in obese children and compare the results with their non-obese peers.
2 METHODS
2.1 Ethical aspects
The study was approved by the Research Ethics Committee of Universidade Norte do Paraná (UNOPAR) (protocol number #1,032,186) and was conducted by resolution 466/12 of the National Health Council of Brazil. After being invited to participate in the study and informed about the objectives and methodology of the study, the children, as well as their guardians, signed an informed consent form.
2.2 Sample
Thirty children, of both sexes, aged between 7 and 13 years, were recruited for convenience and divided into two groups: obese group (N =15; 6 boys and 9 girls) and non-obese control group (N =15; 6 boys and 9 girls). According to the recommendations from WHO (Physical status: the use and interpretation of anthropometry. Report of a WHO Expert Committee, 1995), obesity indicators were defined based on the calculation of the Body Mass Index (BMI), adopting cutoff points for childhood obesity according to sex and age, as suggested by the International Task Force on Obesity (COLE; BELLIZZI; FLEGAL; DIETZ, 2000). For both groups, the exclusion criteria were: (1) previous history of surgery on the musculoskeletal system, (2) presence of musculoskeletal, respiratory, neurological, and/or cardiovascular diseases, (3) patients with diabetes, (4) use of medication daily or in the period of 30 days that precede the day of the evaluation and (5) have received or are receiving any type of treatment for postural alterations or balance problems.
2.3 Data collection instruments
The Physical Activity Questionnaire for Children (PAQ-C) (GUEDES; LOPES; GUEDES, 2005) was applied to assess the participant’s level of physical activity. Body weight was measured using a digital scale (W801-WISO, Florianópolis-SC). Height was measured using a WCS stadiometer (Cardiomed, Curitiba-PR). Postural balance was assessed using a force platform (BIOMEC400; EMG System do Brasil, SP Ltda.) The following variables were analyzed: center of pressure (COP) ellipse area (in cm2), mean velocity of COP oscillations (in cm/s), and mean frequency of COP oscillations (in Hz) in the anteroposterior (AP) and mediolateral (ML) movement directions. Ground reaction force signals from force platform measurements were collected in a 100 Hz sample. All force signals recorded by the platform were filtered with a second-order Butterworth low-pass filter at 35 Hz. For the acquisition and treatment of balance parameters, the captured signals were converted using a stabilographic analysis, which was compiled with MATLAB routines (The Mathworks, Natick, MA).
2.4 Experimental protocol
After familiarization with the equipment and with the experimental protocol, the two-leg (bipedal) and one-leg static (unipedal) balance tests were performed under the force platform in randomized order with a 5-minute rest between the two tests. For the bipedal support test, two attempts of 60s with a rest interval of 30s between each attempt were agreed. The static test in unipedal support was performed on the dominant lower limb for the 30s, with 3 attempts being agreed upon with rest periods of 30s between attempts. The balance protocol was performed with bare feet, eyes open, arms alongside the body, and eyes directed towards a target (black circle placed at the height of the participant’s eyes) set 2.5 meters away in front of the force platform.
2.5 Data analysis
Data were analyzed descriptively with mean and standard deviation. The distribution of normality of the data was verified using the Shapiro-Wilk test. After establishing normality, the groups were compared using Student’s t-test for independent samples. Pearson’s correlations were used to verify the correlation between BMI and postural balance variables. All statistical analyses were performed using the SPSS statistical program (version 21.0). The p-value was set at 5%
3 RESULTS
The participants’ baseline characteristics are shown in Table 01. No significant differences (p > 0,05) were observed between the groups regarding age, height, and level of physical activity. Both groups were classified as moderately active according to the PAQ-C score (DA SILVA; MALINA, 2000). There were significant (p < 0.05) differences between groups in weight and BMI.
| Table 1. Descriptive data and physical activity level (PAQ-C). | |||
| Obese (N = 15) | Control (N = 15) | p-value | |
| Age (years) | 8.8 ± 1.9 | 8.5 ± 2.1 | 0.65 |
| Height (m) | 1.40 ± 0.11 | 1.34 ± 0.08 | 0.11 |
| PAQ-C (score) | 2.83 ± 0.55 | 2.84 ± 0.62 | 0.94 |
| Weight (kg) | 53.3 ± 13.6 | 28.3 ± 9.2 | < 0.0001* |
| BMI (kg/m2) | 26.0 ± 2.7 | 16.3 ± 2.2 | < 0.0001* |
| Values are means ± SD. BMI = Body Mass Index. *Significance difference at p <0,05. | |||
The postural balance data are shown in Table 2. For both the bipedal and unipedal stance tests, the non-obese control group showed better results than the obese group in terms of AP and ML velocity and frequency.
| Tabela 2. Postural balance data for bipedal and unipead tests. | |||
| Obese (N = 15) | Control(N = 15) | p-value | |
| Bipedal stance test | |||
| COP area (cm²) | 3.76 ± 1.8 | 3.73 ± 1.9 | 0.96 |
| Velocity (cm/s) | |||
| AP | 3.55 ± 1.0 | 2.34 ± 1.6 | 0.02* |
| ML | 3.60 ± 1.0 | 2.33 ± 1.9 | 0.03* |
| Frequency (Hz) | |||
| AP | 0.77 ± 0.3 | 0.38 ± 0.1 | <0.0001* |
| ML | 1.45 ± 0.6 | 0.87 ± 0.3 | 0.002* |
| Unipedal stance test | |||
| COP area (cm²) | 11.84 ± 5.2 | 11.60 ± 6.6 | 0.91 |
| Velocity (cm/s) | |||
| AP | 6.07 ± 2.9 | 4.25 ± 1.2 | 0.03* |
| ML | 6.71 ± 5.6 | 4.07 ± 0.8 | 0,08 |
| Frequency (Hz) | |||
| AP | 1.06 ± 0.2 | 0.79 ± 0.2 | 0.004* |
| ML | 1.15 ± 0.3 | 0.91 ± 0.1 | 0.005* |
| Values are means ± standard deviation. COP = Center of pressure; AP = Anteroposterior; ML = Mediolateral. *Significance difference at p <0,05. | |||
The Pearson’s correlation coefficients between BMI and postural balance are shown in Table 3. For the bipedal stance test, there were moderate correlations between BMI and AP and ML velocities and a strong correlation for AP and ML frequency. For the unipedal stance test, there were moderate correlations between BMI and AP velocity, and AP and ML frequency.
| Table 3. Person’s correlations between BMI and postural balance variables. | ||
| Bipedal stance test | Unipedal stance test | |
| BMI | BMI | |
| COP area (cm2) | r = -0.16; p = 0.38 | r = 0.09; p = 0.63 |
| Velocity (cm/s) | ||
| AP | r = 0.40; p = 0.02* | r = 0.39; p = 0.03* |
| ML | r = 0.37; p = 0.04* | r = 0.431; p = 0.09 |
| Frequency (Hz) | ||
| AP | r = 0.64; p = 0.001* | r = 0.52; p = 0.003* |
| ML | r = 0.65; p = 0.001* | r = 0.45; p = 0.01* |
| COP = Center of pressure; AP = Anteroposterior e ML = Mediolateral. *Significance level at p <0,05. | ||
4 DISCUSSION
Although the results of the physical activity questionnaire (PAQ-C) revealed no difference between the two groups, which were considered moderately active, some balance parameters based on the COP showed better results in favor of the group of non-obese children. These results suggest that simply practicing regular physical activity would not be enough for obese children to be equated with non-obese children in terms of postural balance. Within this scenario, the basic priorities for action must be linked to potentially satisfactory intervention strategies with the inclusion of a physical activity program aimed specifically at postural balance, which may provide better performance in obese children.
The ideal alignment of the center of mass and the center of pressure passes between the ankles, slightly in front of the joint axes (WINTER, 1990). Excess weight causes anterior displacement of the center of mass, especially when the fat is mostly located in the abdominal region, thus modifying the alignment of force vectors and, consequently, the muscle forces needed to maintain balance (WINTER, 1990). Obesity therefore leads to a considerable risk of falling, with a prevalence when excess fat is located at the abdominal level.
The study of Li and Aruin (LI; ARUIN, 2005) evaluated the influence of body overload on postural control in a position of anterior imbalance. The task consisted of holding a 2.7 kg weight that was dropped from a height of 10 cm towards the hands. This test was also performed by adding up to 40% of the body weight in a symmetrical manner on the shoulders, trunk, and legs, to reproduce obesity. The results showed that when there was an increase in weight, postural control decreased and imbalance increased, represented by greater displacement of the center of pressure. The study by Colné et al. (COLNÉ; FRELUT; PÉRÈS; THOUMIE, 2008) compared the trajectory of the center of pressure of obese and non-obese adolescents. The results showed that the displacement of the center of pressure is greater in obese adolescents in the orthostatic position and during backward displacement. In another study on the postural balance of obese and non-obese children aged 8 to 10 years, differences were found in the parameters of balance between the two groups. In the group of obese children, a greater surface area of oscillations, greater consumption of energy, and a more accentuated mediolateral instability were observed (MCGRAW; MCCLENAGHAN; WILLIAMS; DICKERSON et al., 2000).
Obese children tend to shift their center of pressure more anteriorly than non-obese children, thus being subjected to an initial disturbance that would imply the development of an additional moment of force at the ankle level to prevent this disturbance to keep your balance (BERNARD; GERACI; HUE; AMATO et al., 2003; CORBEIL; SIMONEAU; RANCOURT; TREMBLAY et al., 2001). Therefore, to maintain balance, obese people maintain a posteriorized position of the center of plantar pressure (BERNARD; GERACI; HUE; AMATO et al., 2003). This statement, combined with the lack of significant difference between the two groups in the ellipse area of the COP, suggests that, at rest, the initial disturbance would be efficiently compensated by obese children. However, the differences in the speed and mean frequency of COP oscillations suggest a lower ability to maintain postural balance compared to non-obese children. Blaszczyk and collaborators (BŁASZCZYK; CIEŚLINSKA-SWIDER; PLEWA; ZAHORSKA-MARKIEWICZ et al., 2009) evaluated the displacement of the center of pressure in an orthostatic position, with eyes open, with eyes closed and during a forward displacement. The authors noted that it is more difficult to disturb the balance of obese people, but that, once disturbed, it becomes more difficult for obese people to recover the lost balance. The increase in the initial moment of force, induced by the anterior displacement of the center of mass of the obese, represents an additional factor throughout the balance stabilization process (CORBEIL; SIMONEAU; RANCOURT; TREMBLAY et al., 2001), leading obese children to greater difficulty in effectively controlling their posture during the tests.
Obese children have greater difficulty regulating their balance efficiently when subjected to the influence of external disturbances (BERNARD; GERACI; HUE; AMATO et al., 2003), therefore, the stability of the trunk and the tone of its muscles seem to be influenced by obesity. The increase in the volume of the abdomen and abdominal hypotonia cause greater lumbosacral muscle tension and a lordotic attitude, thus, the imbalance of these muscle masses could be responsible for the decrease in postural response capacity (BOUISSET; MATON, 1995) and would partly explain the significant differences found between the two groups for the studied balance parameters. Because of this, it would be important to encourage obese children to perform physical activities not only to reduce their body weight but also, through specific exercises, to acquire better postural control and reduce balance problems.
Our correlation results between balance parameters and BMI corroborate the studies by Sasidharan et al. (SASIDHARAN; VIJAYAPPAN; PILLAI; KHAN, 2014) who showed a greater balance difficulty with the increase in BMI in obese children aged between 8 and 13 years. Excess weight reduces the sensitivity of mechanoreceptors in the foot, creating larger plantar contact areas and increasing pressure in the distal area of the toes, midfoot, and metatarsals (SASIDHARAN; VIJAYAPPAN; PILLAI; KHAN, 2014). This reduces the involvement of foot mechanoreceptors during balance control reactions (RIEMANN; LEPHART, 2002; SASIDHARAN; VIJAYAPPAN; PILLAI; KHAN, 2014). These functional limitations may represent a potential source of inactivity, which appears to be particularly widespread in obese people. The predominance of falls due to imbalance during walking and the increase in the number of fractures following a fall are closely linked to obesity (FJELDSTAD; FJELDSTAD; ACREE; NICKEL et al., 2008). The problems that obese people may encounter while walking and performing tasks that require a certain amount of postural control show the need to solve not only their metabolic problems but also their physical limitations. Thus, balance seems to be a basic physical ability to perform other tasks, where the good performance of the postural balance function, which translates to greater or lesser plasticity of the central nervous system, allows the child to respond to problem situations that he encounters. and its confrontation with the environment (CAMARGO, 2010).
5 CONCLUSIONS
Obese children have worse postural balance compared to their non-obese peers, presumably due to the restrictions exerted by excess weight on the control of the anteroposterior and mediolateral displacement of the body. Considering that postural control is fundamental for activities of daily living at all ages, participation in nutritional guidance programs and physical exercises aimed at losing weight is essential for obese children between 7 and 13 years old.
REFERENCES
BENEDETTI, M. G.; DI GIOIA, A.; CONTI, L.; BERTI, L. et al. Physical activity monitoring in obese people in the real life environment. J Neuroeng Rehabil, 6, p. 47, Dec 30 2009.
BERNARD, P. L.; GERACI, M.; HUE, O.; AMATO, M. et al. [Influence of obesity on postural capacities of teenagers. Preliminary study]. Ann Readapt Med Phys, 46, n. 4, p. 184-190, May 2003.
BŁASZCZYK, J. W.; CIEŚLINSKA-SWIDER, J.; PLEWA, M.; ZAHORSKA-MARKIEWICZ, B. et al. Effects of excessive body weight on postural control. J Biomech, 42, n. 9, p. 1295-1300, Jun 19 2009.
BOUISSET, S.; MATON, B. Muscles, posture et mouvement; base et applications de la méthode électromyographique. Paris: 1995.
CAMARGO, D. LE BOULCH, Jean. O corpo na escola no século XXI: práticas corporais. Tradução de Cristiane Hirata. São Paulo: Phorte, 2008. Práxis Educativa, 5, n. 2, p. 233-235, 12/30 2010.
COLE, T. J.; BELLIZZI, M. C.; FLEGAL, K. M.; DIETZ, W. H. Establishing a standard definition for child overweight and obesity worldwide: international survey. Bmj, 320, n. 7244, p. 1240-1243, May 6 2000.
COLNÉ, P.; FRELUT, M. L.; PÉRÈS, G.; THOUMIE, P. Postural control in obese adolescents assessed by limits of stability and gait initiation. Gait Posture, 28, n. 1, p. 164-169, Jul 2008.
CORBEIL, P.; SIMONEAU, M.; RANCOURT, D.; TREMBLAY, A. et al. Increased risk for falling associated with obesity: mathematical modeling of postural control. IEEE Trans Neural Syst Rehabil Eng, 9, n. 2, p. 126-136, Jun 2001.
DA SILVA, R. C.; MALINA, R. M. [Level of physical activity in adolescents from Niterói, Rio de Janeiro, Brazil]. Cad Saude Publica, 16, n. 4, p. 1091-1097, Oct-Dec 2000.
DEVITA, P.; HORTOBÁGYI, T. Obesity is not associated with increased knee joint torque and power during level walking. J Biomech, 36, n. 9, p. 1355-1362, Sep 2003.
EDUCAÇÃO., B. M. d. Obesidade infantil é tema do programa Salto para o Futuro. http://portal.mec.gov.br/ultimas-noticias/33491-tv-escola/63021-obesidade-infantil-e-tema-do-programa-salto-para-o-futuro, 2018. Acesso em: 22 de abril.
FJELDSTAD, C.; FJELDSTAD, A. S.; ACREE, L. S.; NICKEL, K. J. et al. The influence of obesity on falls and quality of life. Dyn Med, 7, p. 4, Feb 27 2008.
GOULDING, A.; TAYLOR, R. W.; JONES, I. E.; MCAULEY, K. A. et al. Overweight and obese children have low bone mass and area for their weight. Int J Obes Relat Metab Disord, 24, n. 5, p. 627-632, May 2000.
GUEDES, D. P.; LOPES, C. C.; GUEDES, J. E. R. P. Reprodutibilidade e validade do Questionário Internacional de Atividade Física em adolescentes. Revista Brasileira de Medicina do Esporte, 11, n. 2, p. 151-158, 2005.
HILLS, A. P.; PARKER, A. W. Gait characteristics of obese children. Arch Phys Med Rehabil, 72, n. 6, p. 403-407, May 1991.
HUE, O.; SIMONEAU, M.; MARCOTTE, J.; BERRIGAN, F. et al. Body weight is a strong predictor of postural stability. Gait Posture, 26, n. 1, p. 32-38, Jun 2007.
KO, S.; STENHOLM, S.; FERRUCCI, L. Characteristic gait patterns in older adults with obesity–results from the Baltimore Longitudinal Study of Aging. J Biomech, 43, n. 6, p. 1104-1110, Apr 19 2010.
LI, X.; ARUIN, A. The effect of changes in body mass distribution on feed-forward postural control: a pilot study. Conf Proc IEEE Eng Med Biol Soc, 2005, p. 7444-7447, 2005.
MCGRAW, B.; MCCLENAGHAN, B. A.; WILLIAMS, H. G.; DICKERSON, J. et al. Gait and postural stability in obese and nonobese prepubertal boys. Arch Phys Med Rehabil, 81, n. 4, p. 484-489, Apr 2000.
MELLO, E. D.; LUFT, V. C.; MEYER, F. [Childhood obesity–towards effectiveness]. J Pediatr (Rio J), 80, n. 3, p. 173-182, May-Jun 2004.
Physical status: the use and interpretation of anthropometry. Report of a WHO Expert Committee. World Health Organ Tech Rep Ser, 854, p. 1-452, 1995.
POLLOCK, A. S.; DURWARD, B. R.; ROWE, P. J.; PAUL, J. P. What is balance? Clin Rehabil, 14, n. 4, p. 402-406, Aug 2000.
RIEMANN, B. L.; LEPHART, S. M. The sensorimotor system, part I: the physiologic basis of functional joint stability. J Athl Train, 37, n. 1, p. 71-79, Jan 2002.
SASIDHARAN, A.; VIJAYAPPAN, V.; PILLAI, S.; KHAN, F. Correlation between obesity and balance in school children. International Journal of Therapy and Rehabilitation, 21, p. 36-39, 01/01 2014.
VOLERY, M.; CARRARD, I.; ROUGET, P.; ARCHINARD, M. et al. Cognitive distortions in obese patients with or without eating disorders. Eat Weight Disord, 11, n. 4, p. e123-126, Dec 2006.
WINTER, D. A., 1990, Biomechanics and Motor Control of Human Movement.
WINTER, D. A. Human balance and posture control during standing and walking. Gait & Posture, 3, n. 4, p. 193-214, 1995/12/01/ 1995.
¹Master’s student in the Physical Exercise in Health Promotion program, North Paraná University (UNOPAR), email: maike_mmd@hotmail.com;
²Lecturer at North Paraná University (UNOPAR), Post Doctor from McMaster University (Canada), email: afaguiarunesp@gmail.com;
³Doctoral student in rehabilitation sciences at North Paraná University (UNOPAR), email: anaapaulanascimento@gmail.com;
4Lecturer at North Paraná University (UNOPAR), Doctor in Physical Education from the State University of Londrina, email: juliano2608@hotmail.com;
5Master in Physical Exercise in Health Promotion, North Paraná University (UNOPAR), email: rafaelpasq@hotmail.com;
6 Department of Health Sciences, Physical Therapy Program at McGill University offered as an extension at the University of Quebec at Chicoutimi (UQAC) University, Saguenay City, Quebec, Canada. Email: Rubens_DaSilva@uqac.ca
7Doctoral student in rehabilitation sciences at North Paraná University (UNOPAR), email: fabiana.antunes@outlook.com;
8Lecturer at North Paraná University (UNOPAR), Post Doctor from the University of Montreal (Canada), email: erosjunior@hotmail.com
*Orientadores do trabalho