Does bad posture affect the standing balance?

Abstract

Introduction: Bad posture is a well-known problem in children and adolescents, and it has a negative effect in adulthood. It can be hypothesized that due to bad posture, changes in the body’s position cause changes in standing balance. Objective: The objective of the study is to determine the influence of bad posture on the standing balance of school-aged children based on independent time–distance- and frequency-based foot centre-of-pressure parameters. Subjects and Methods: Subjects included 171 children (113 with neutral posture (70 boys and 73 girls), mean age: 10.7 ± 1.1 years (range: 9–13), and 68 with bad posture (22 boys and 46 girls), mean age: 10.7 ± 1.2 (range: 9–13)). The parameters were derived from the motion of the centre of pressure on a platform equipped with pressure sensors, on which the subjects were standing for 60 s with both feet and open eyes. Results: When comparing the two groups, the load distribution difference between the legs and the medium–high-frequency band power ratio in the mediolateral direction showed a significant difference out of 17 centre-of-pressure parameters. However, the other 15 parameters did not show any significant differences. Conclusion: There is no clearly significant degradation of postural control in children with bad posture, as the effects of altered posture are continuously corrected by the central nervous system. The asymmetric load between the two sides may further degrade muscular imbalance; thus, correcting bad posture is an important task of physiotherapy.

Full text

ORTHOPEDICS | RESEARCH ARTICLE
Does bad posture affect the standing balance?
Gergely Nagymáté
1
*, Mária Takács
2
and Rita M. Kiss
1
Abstract: Introduction: Bad posture is a well-known problem in children and
adolescents, and it has a negative effect in adulthood. It can be hypothesized that
due to bad posture, changes in the body’s position cause changes in standing
balance.
Objective: The objective of the study is to determine the influence of bad posture
on the standing balance of school-aged children based on independent time–dis-
tance- and frequency-based foot centre-of-pressure parameters.
Subjects and Methods: Subjects included 171 children (113 with neutral posture (70
boys and 73 girls), mean age: 10.7 ± 1.1 years (range: 9–13), and 68 with bad posture (22
boys and 46 girls), mean age: 10.7 ± 1.2 (range: 9–13)). The parameters were derived
from the motion of the centre of pressure on a platform equipped with pressure sensors,
on which the subjects were standing for 60 s with both feet and open eyes.
Results: When comparing the two groups, the load distribution difference
between the legs and the medium–high-frequency band power ratio in the medio-
lateral direction showed a significant difference out of 17 centre-of-pressure para-
meters. However, the other 15 parameters did not show any significant differences.
Conclusion: There is no clearly significant degradation of postural control in
children with bad posture, as the effects of altered posture are continuously cor-
rected by the central nervous system. The asymmetric load between the two sides
may further degrade muscular imbalance; thus, correcting bad posture is an
important task of physiotherapy.
Subjects: Biomedical Engineering; Physiotherapy and Sports Medicine; Orthopedics;
Rehabilitation Medicine; Physiotherapy
Keywords: standing balance; COP; children; bad posture
ABOUT THE AUTHOR
Gergely Nagymáté The Motion Laboratory is part
of Department of Mechatronics, Optics and
Mechanical Engineering Informatics at Budapest
University of Technology and Economics. The
main research focus of the laboratory is motion
analysis using optical motion capture systems,
stabilometry and equilibrium analysis after sud-
den perturbation in healthy subjects and in
patients with different orthopaedic diseases. The
other focus of the research group is the devel-
opment and validation of different motion ana-
lysis methods. The laboratory regularly works
together with hospitals in special studies and
basic studies.
PUBLIC INTEREST STATEMENT
Bad posture is a well-known problem in children
and adolescents, and it has a negative effect in
adulthood. It can be hypothesized that due to
bad posture, changes in the body’s position cause
changes in standing balance. The goal of the
study is to determine the influence of bad posture
on the standing balance of school-aged children
based on time–distance- and frequency-based
foot centre-of-pressure parameters.
Nagymáté et al., Cogent Medicine (2018), 5: 1503778
https://doi.org/10.1080/2331205X.2018.1503778
© 2018 The Author(s). This open access article is distributed under a Creative Commons
Attribution (CC-BY) 4.0 license.
Received: 13 March 2018
Accepted: 19 July 2018
First Published: 23 July 2018
*Corresponding author Gergely
Nagymáté, Department of
Mechatronics, Optics and Mechanical
Engineering Informatics, Budapest
University of Technology and
Economics, H-1111 Budapest
Műegyetem Rakpart 3, Hungary
Email: nagymate@mogi.bme.hu
Reviewing editor:
Omid Khaiyat, Liverpool Hope
University, UK
Additional information is available at
the end of the article
Page 1 of 12

1. Introduction
Keeping balance is a dynamic central nervous system (CNS)-controlled process, which could be
affected by visual, vestibular and various orthopaedic lesions (Pauk, Daunoraviciene, Ihnatouski,
Griskevicius, & Raso, 2010). According to the definition, standing balance (or static postural control)
is the ability to keep the body “motionless”in a given circumstance and in a given position, i.e., to
stabilize and minimize the movements of the centre of mass (COM) (Hasan et al., 1996;Panzer,
Bandinelli, & Hallett, 1995). With the help of the inverted pendulum principle, it can be proved that
during standing, the movement of the COM can be characterized properly by the movement of the
foot centre of pressure (COP) (Hasan et al., 1996). During standing, COP excursionsare computedfrom
the ground reaction forces, which provide an indication of postural control during quiet standing.
Numerous COP parameters can be derived from the acquired two-dimensional COP coordinates
during the measurement interval (Scoppa, Capra, Gallamini, & Shiffer, 2013; Verbecque, Vereeck, &
Hallemans, 2016). The posture and standing balance in children and in young adults are usually
characterized by the postural index (PI), which is assessed by dropping a vertical plumb line from the
C7 vertebral body centre and quantifying the distance of other anatomical landmarks from this
vertical. Several studies have shown that spinal deformities in children and in young adults have a
significant influence on standing balance, which is characterized by the PI (Dubousset, 1994;El
Fegoun et al., 2005; Glassman et al., 2005; Jackson, Peterson, McManus, & Hales, 1998).
Bad posture is a well-known problem in children and young adults, and it has a negative effect in
adulthood (Aggarwal, Anand, Kishore, & Ingle, 2013; Schmidt et al., 2014). With bad posture, there
is no structural abnormality on the spine; thus, the child is able to briefly produce normal posture
with attention. Bad posture is the most widespread two-dimensional spine deformity. The abnor-
mal curvature of the spine occurs only in the sagittal plane. The clinical characteristics are forward-
falling shoulders, protruding scapula and protruding belly. The child is capable of moving out from
the bad posture but find the long-term maintenance of the correct posture challenging. However,
on the basis of the results of non-invasive measurement, it can be established that the posture
significantly affects spinal curvatures (thoracic kyphosis (TK) and lumbar lordosis (LL)), inclination
(total trunk inclination (TTI) and lateral inclination (LI)), (Takács, Rudner, Kovács, Orlovits, & Kiss,
2015) and the postural index (PI) (Ludwig, Mazet, Mazet, Hammes, & Schmitt, 2016).
Even small deviations in body position are regulated by postural adjustments relying on both
feedback and feedforward control mechanisms (Bottaro, Casadio, Morasso, & Sanguineti, 2005;
Collins & De Luca, 1993). This regulation is obtained through appropriate torques produced by the
feet on the base of support (Morasso & Schieppati, 1999).
Ludwig (2017) established that there is no significant correlation between PI and the sway path
length calculated from COP movements. His research proved that due to bad posture, the sway path
lengths calculated from the COP values measured in a 20-s-long bipedal open-eyed position did not
show any significant differences. No other research has been found on the analysis of the effect of bad
posture on standing balance in children. However, this topic is very important, as standing balance is
constantly evolving and significantly changing in childhood (Verbecque et al., 2016). The aim of this
study is to investigate whether bad posture influences standing balance parameters among school-
aged children compared to those of school-aged children with neutral posture. It is hypothesized that
bad posture significantly affects standing balance, which is reflected in COP motion. In the present
study, 17 independent time–distance- and frequency-based parameters determined from COP motion
were used to characterize standing balance (Nagymáté & Kiss, 2016a,2016b).
2. Materials and methods
2.1. Subjects
The basic criterion for the subjects was being 6–14 years of age. A total of 347 children were
screened for the study (102 boys and 245 girls). Conditions for exclusion included the following:
any minor orthopaedic lesion of the lower limbs, surgery in the past 6 months, lower extremity
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injury, spine deformity (scoliosis, Scheuermann’s disease), pronated (pes planus) or supinated foot
structure, cerebral palsy, cerebral concussion, visual or vestibular disorder, ±5 dioptres of vision
correction, inner ear infection at the time of the examination, upper respiratory infection or head
cold. We also excluded children who regularly performed exercises that improve balancing ability
at high levels (e.g., ballet, sailing, tai chi). The research was authorized by the Research Ethics
Committee of MÁV Hospital (license number: FI/5-93/2007). The parents of the subjects received
detailed verbal and written information in each case before they signed the consent form.
The children who had been selected as described above were divided, using a physical ortho-
paedic examination, into two groups based on their posture. During the body’s natural posture, if
no spinal deformity, asymmetry on the trunk, abnormal shoulders or shoulder blades were
observed, the child was considered to have normal body posture. Children with protruding shoulder
blades, rounded shoulders and protruding abdomen were classified into the bad posture group.
Body posture can be characterized by TK and LL angles. X-ray images were not taken in children
with normal or bad posture. The body posture characterizers TK, LL, TTI and LI were determined
with a non-invasive method, the ZEBRIS spine examination method (Takács et al., 2015), after the
groups had been formed. Two groups—one with 113 children of neutral posture and another with
58 children of bad posture—were formed.
2.2. Measurement method
Standing balance measurements were carried out with a Zebris FDM-S multifunctional Force
Distribution Measuring plate (320 mm × 470 mm measuring surface with 1504 pcs. load cells)
(ZEBRIS GmbH, Isny, Germany) at the Biomechanical Laboratory of MÁV Hospital (Szolnok,
Hungary). Vertical force distribution was recorded by the Zebris WinPDMS processing software
(v1.2, ZEBRIS GmbH, Isny, Germany) at 100 Hz.
Each subject performed 60-s trials of barefoot bipedal stances with their eyes open in daylight.
The subjects were positioned in a relaxed bipedal standing, while the distance between the two
ankle joint centres was equal to the distance between the right and left anterior superior iliac
spines. Both limbs were in full knee extension, the heels were aligned in a line, the feet were
parallel and faced forward and the arms were resting by the sides. The subjects focused on a black
mark placed approximately 3 m away at eye level on a white wall in front of them. Correct feet
placement had to be held throughout the examinations because changes could affect stabilome-
try parameters (Chiari, Rocchi, & Cappello, 2002). Every subject was asked to perform the required
60-s bipedal standing as motionlessly as possible. Subjects were given one practice and one test
trial, with 1-min rest periods between the consecutive trials. The trials were accepted only when
the subjects maintained the required position for a minimum of 60 consecutive seconds. If they
were not able to keep balance, they could repeat the measurements once more. If they could not
succeed, they were excluded from the study.
2.3. Calculated parameters
Further data processing and COP parameter calculations were carried out on exported raw
measurement data in a custom application written in LabVIEW v2013 (National Instruments
Inc., Austin, Texas). The calculated instantaneous COP coordinates were filtered with a
Butterworth low-pass digital filter with a cut-off frequency of 10 Hz, as recommended by Ruhe,
Fejer, and Walker (2010). From the COP position signals, a power spectrum was obtained using the
fast Fourier transformation (FFT) with a Hanning filtering window. A total of 17 time–distance- and
frequency-based parameters were calculated from the COP position (Table 1), which are recom-
mended as independent parameters (Nagymáté & Kiss, 2016a,2016b).
2.4. Statistical methods
To analyse the impact of bad posture, the average and standard deviation of the selected
parameters were calculated for both groups as basic statistical features. Normal distributions of
the samples were tested with the Shapiro–Wilk normality test. As each of the parameters failed to
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fit the hypothesized normal distribution of the data (p< 0.05 in the Shapiro–Wilk test), the Mann–
Whitney U test was used to compare means. The effect size was calculated according to Cohen
(1988)asr=Z/√N, where Zis the value from the Mann–Whitney U test and Nis the overall sample
size. The means were compared between the control group and the bad posture group for mixed
genders and also by gender. These analyses were carried out with SPSS Statistics version 22 (IBM
Corporation, New York, USA). The achieved statistical power for the mixed group comparisons and
the significant deviations in the gender-wise comparison was calculated from the effect size and
group sample sizes for two-tailed Wilcoxon–Mann–Whitney test by G*Power version 3.1.9.2 (Faul,
Erdfelder, Lang, & Buchner, 2007)
3. Results
A total of 347 children were screened for the study. According to the inclusion and exclusion
criteria, 12 children were excluded due to minor orthopaedic lesions, surgery or injuries; 24
were excluded due to scoliosis or Scheuermann’s disease; 91 children due to pes planus
(pronated, flat arched); 28 children due to supinated foot type; 3 due to cerebral concussions
or visual or vestibular disorders; 2 due to a visual correction of ±5 dioptres; and 6 due to the
regular performance of exercises that greatly improve balancing ability. The remaining 181
children were divided into two groups according to posture. A neutral posture group with 113
children and a bad posture group with 68 children were formed. The characteristics of the
subjects in the two groups (neutral and bad posture) are shown in Table 2. Anthropometric
data (age, height and weight), TK and TTI did not differ significantly, whereas LL and LI differed
significantly in the two groups.
All subjects in the neutral group (113) were able to perform the 60-s bipedal open-eyed standing
activity on their first attempt, whereas the test had to be repeated due to a loss of balance in the
case of 12 out of 68 children in the bad posture group. However, nobody was excluded. The
average and standard values of the selected parameters in both groups are shown in Table 3.
When the means of the control group and the bad posture group were compared, significant
differences were found in the load distribution difference (LDD) between the legs (p= 0.021) and in
the mediolateral directional medium–high-frequency band power ratio (ML MHR) (p= 0.002). For
the other parameters, the differences were not significant (p≥0.108). From gender comparisons
(Table 4), it can be seen that not many parameters show differences compared to the mixed
group; however, COP path length is significantly longer in the bad posture group for girls (p= 0.041,
power = 0.16) and did not show significant differences in the mixed group or for the boys. On the
other hand, the AP LA parameter shows improvement (p= 0.039, power = 0.15) in boys with bad
posture compared to the boys in the control group (Table 4).
4. Discussion
Bad posture was found in 68 out of 347 subjects based on the inclusion and exclusion criteria.
Significant differences were found in the case of LL and LI, which indicate the differences in the
posture of the groups (Table 2). This finding is consistent with our previous research findings
(Takács et al., 2015). It is also known from the literature that even a slight change in body
posture can be detected in the standing balance (Bottaro et al., 2005; Collins & De Luca, 1993).
The aim of the study is to investigate whether bad posture influences the standing balance
parameters in school-aged children compared to neutral posture. By studying the literature, it
can be stated that only one research study analysed standing balance in children with bad
posture on the basis of sway path length; however, the results were not compared to the
results of children with neutral posture (Ludwig, 2017). Our study characterizes the standing
balance of children with bad posture using 17 independent parameters (Nagymáté & Kiss,
2016a,2016b) based on the results of 68 children’smeasurements(Table3).
In the neutral group, the maximum velocity, the 95% CE area and the path length (Table 3) are
consistent with the results previously found in young subjects (Sakaguchi, Taguchi, Miyashita, &
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Table 1. Studied parameters
Parameter name Dimension Description
Time–distance parameters
Confidence ellipse area (CE area) mm
2
The area of the 95% confidence ellipse around the COP
trajectory (Oliveira, Simpson, & Nadal, 1996).
Confidence ellipse axis ratio (CE axis ratio) 1 The ratio between the major and the minor axes of the 95%
confidence ellipse that describes the shape of the COP’s
trajectory expansion.
Path length mm The length of the total COP trajectory during the
measurement.
Maximum path velocity mm/s The filtered maximum distance between consecutive COP
points divided by the sampling interval.
AP–ML range ratio 1 The ratio of the largest COP path expansions in the
anteroposterior (AP) and mediolateral (ML) directions that
describes the relation of the largest random errors of
postural control between the two anatomical directions.
Anterior (AP+) and posterior (AP-) maximum deviations mm The maximum excursions in the anterior and posterior
direction relative to the average COP point in the AP–ML
plane
Largest amplitude during balancing (LA) mm The largest continuous motion in both the AP and the ML
directions, which are not necessarily equal to the
corresponding COP range. This parameter is similar to the
sub-movement size that was defined by Hernandez, Ashton-
Miller, and Alexander (2012) for targeted COP movements.
Frequency parameters
Frequency power ratios between low–medium- and
medium–high-frequency bands (LMR, MHR)
1 Provide information about the power distribution of postural
sway in the frequency domain. The defined limits of the
compared frequency bands are low- (0–0.3 Hz), medium-
(0.3–1 Hz) and high-frequency (1–5 Hz) bands (Nagy et al.,
2004).
(Continued)
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Table1. (Continued)
Parameter name Dimension Description
Mean power frequency (MPF) Hz A weighted-average frequency where f
j
frequency
components are weighted by their P
j
power. Mis the number
of frequency bins. MPF is calculated as proposed by Oskoei
and Hu (2008), according to the following equation:
MPF ¼P
M
j¼1
fjPj=P
M
j¼1
Pj
Spectral power ratio (SPR) 1 The ratio of the total spectral power in the AP direction and
the total spectral power in the ML direction. SPR characterizes
the rate of the power distribution of postural sway
frequencies in the AP/ML directions.
Other
Load distribution difference (LDD) % Shows the difference in the weight load on the lower limbs.
This parameter is not derived from COP motion, but it is used
by the original Zebris WinPDMS software, together with the
COP parameters, and is proven to be very useful in
biomechanical analyses (Duffell, Gulati, Southgate, &
McGregor, 2013; Nagymate, Pethes, Szabo, Bejek, & Kiss,
2015).
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Katsuno, 1994). To our knowledge, this is the first article on standing balance analysed with
distance-, time- and frequency-based parameters and calculated from the results of 60-s mea-
surements of children with bad posture. Thus, there were no reference values for many examined
time–distance- and frequency-based parameters published earlier in the literature (Verbecque
Table 2. Data of the subjects (mean ± standard deviation)
Neutral posture group Bad posture group
N113 68
40 boys 73 girls 22 boys 46 girls
Age (years) 10.78 ± 0.95 (range:
9–13)
10.73 ± 1.17 (range:
9–13)
10.82 ± 0.96 (range:
10–13)
10.67 ± 1.27 (range:
9–13)
Weight (kg) 41.85 ± 9.23 50.77 ± 23.07 39.91 ± 8.93 42.54 ± 11.73
Height (cm) 151.08 ± 7.42 145.96 ± 25.16 149.91 ± 11.55 153.43 ± 9.58
Thoracic kyphosis
(degree)
40.44 ± 8.67 40.08 ± 8.34 44.84 ± 9.68 38.06 ± 8.34
Lumbar lordosis
(degree)
30.37 ± 9.81 36.25 ± 8.63 31.30 ± 13.55 32.55 ± 9.31
Total trunk
inclination (degree)
5.04 ± 2.56 4.12 ± 2.62 4.11 ± 2.83 4.23 ± 2.48
Lateral inclination
(degree)
2.34 ± 2.02 1.99 ± 1.67 1.91 ± 1.62 1.81 ± 1.43
Table 3. Statistical comparison of the standing balance of the neutral and bad posture groups
based on COP parameters (mean ± standard deviation)
Neutral group Bad posture Mann–Whitney U
test significance
level (p)
Observed power
95% CE axis ratio 1.70 ± 0.59 1.59 ± 0.48 0.285 0.079
95% CE area [mm
2
] 289.83 ± 209.67 279.67 ± 204.33 0.967 0.05
Path length [mm] 923.13 ± 350.32 975.95 ± 326.67 0.158 0.102
Max velocity [mm/s] 130.22 ± 79.86 158.89 ± 167.85 0.329 0.074
AP–ML range ratio 1.28 ± 0.59 1.23 ± 0.38 0.68 0.054
LDD [%] 6.25 ± 5.19 8.15 ± 5.9 0.021 0.192
AP LA [mm] 31.13 ± 17.24 28.45 ± 12.32 0.633 0.056
ML LA [mm] 26.92 ± 14.91 26.64 ± 16.32 0.788 0.052
A max. dev. [mm] 28.86 ± 14.23 27.39 ± 12.97 0.489 0.062
P max. dev. [mm] 28.35 ± 13.09 28.24 ± 14.06 0.763 0.052
AP MPF [Hz] 0.15 ± 0.07 0.16 ± 0.07 0.56 0.059
ML MPF [Hz] 0.19 ± 0.07 0.19 ± 0.09 0.484 0.063
SPR 2.22 ± 3.14 1.90 ± 1.92 0.341 0.073
AP LMR 10.69 ± 9.50 9.80 ± 10.08 0.427 0.066
AP MHR 11.72 ± 6.25 10.37 ± 5.52 0.108 0.118
ML LMR 6.54 ± 5.85 7.59 ± 7.19 0.486 0.062
ML MHR 11.53 ± 5.00 9.18 ± 4.25 0.002 0.05
CE: confidence ellipse; AP: anteroposterior; ML: mediolateral; LDD: load distribution difference between legs; LA:
largest amplitude; A: anterior; P: posterior; max. dev.: maximum deviation; MPF: mean power frequency; SPR: spectral
power ratio; LMR: low-medium band power ratio; MHR: medium–high-frequency band power ratio; bold: significant
difference.
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et al., 2016) because those results were calculated from only 30-s measurements, despite the
standardization recommendations of 60-s measurements (Scoppa et al., 2013).
Balance is a multidimensional motor skill (Sousa, Silva, & Tavares, 2012). Balance regulation is based
on the interaction of sensory information and its processing in the CNS (Chiba, Takakusaki, Yozu, &
Haga, 2016; Kouzaki & Masani, 2012). The proprioceptive function of the sensorimotor control system
matures at 3 to 4 years of age and is stabilized at 6 years (Steindl, Kunz, Schrott-Fischer, & Scholtz,
2006). Therefore, it can be stated that the sensorimotor control of the children involved in the study
(Table 2) is stable and no difference in balance due to age should occur (age range 9–13 years).
Based on our results (Table 3), the standing balance of children with bad posture is similar to that
of children with neutral posture; however, significant differences were found in LDD and in ML MHR.
The other parameters did not show any significant deviations (Table 3), meaning that our hypothesis
is not fully justified. In a previously published study (Ludwig, 2017), only the change of the path
length was analysed. Our results are similar to those of Ludwig (2017): the path length value is
increased due to bad posture, but the difference is not significant (Table 3). When the means are
compared by gender, interesting differences can be observed. The boys with bad posture balance
better than the girls with bad posture. While boys introduced improvement in the AP LA parameter,
showing smaller COP deviations in the AP direction, the girls yielded elongated COP path length. Both
of these parameters are considered reliable COP measures (Nagymáté, Orlovits, & Kiss, 2018);
therefore, these significant differences are remarkable. On the other hand, due to the effect size
and sample count, these results are supported by poor statistical power.
Table 4. Statistical comparison of the standing balance of the neutral and bad posture groups
by gender (mean ± standard deviation)
Difference of
means for boys
[bad posture—
control]
Difference of
means for girls
[bad posture—
control]
Mann–Whitney U test p-value
Boys Girls
95% CE axis ratio −0.23 −0.06 0.317 0.548
95% CE area [mm
2
]−111.84 44.19 0.066 0.128
Path length [mm] 3.46 85.58 0.702 0.041
Max velocity [mm/s] 33.45 27.44 0.791 0.321
AP–ML range ratio −0.01 −0.07 0.769 0.823
LDD [%] 1.49 2.13 0.245 0.036
AP LA [mm] −4.78 −1.48 0.257 0.781
ML LA [mm] −3.27 1.53 0.185 0.416
A max. dev. [mm] −5.85 0.96 0.039 0.471
P max. dev. [mm] −4.37 2.24 0.096 0.377
AP MPF [Hz] 0.01 0.01 0.67 0.559
ML MPF [Hz] 0.03 −0.02 0.659 0.247
SPR −0.23 −0.39 0.537 0.448
AP LMR −2.22 −0.31 0.724 0.422
AP MHR −1.27 −1.5 0.402 0.166
ML LMR −1.48 2.3 0.825 0.31
ML MHR −4.38 −1.32 0.001 0.138
CE: confidence ellipse; AP: anteroposterior; ML: mediolateral; LDD: load distribution difference between legs; LA:
largest amplitude; A: anterior; P: posterior; max. dev.: maximum deviation; MPF: mean power frequency; SPR: spectral
power ratio; LMR: low-medium band power ratio MHR: medium–high-frequency band power ratio; bold: significant
difference.
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It is known from the literature (Ludwig, 2017; Nourbakhsh & Arab, 2002) that bad posture is a
consequence of neuromuscular imbalance. Body posture and standing balance are both complex
and controlled processes influenced by biomechanical and neurophysiological mechanisms (Sousa
et al., 2012). The effect of muscular imbalance is counterbalanced by feedback mechanisms and
by sensory reweighting (Assländer & Peterka, 2014; Peterka, 2002). It can be hypothesized that the
CNS tries to keep the COP in place, in spite of the different positions of the body segments
(forehead, shoulders, projecting shoulder blades, pretensioned abdomen), so the movements of
the COP change only a little in spite of the weak muscles and the altered body posture (Park,
Reimann, & Schöner, 2016). The reason for bad posture is also that maintaining balance in the
improper posture takes less work. This idea is reflected in the measurement of the boys, whose TK
is 6° larger compared to girls, yet the path length does not show degradation, while the AP LA
shows improvement. The observed worsening of distance-type parameters, which is not significant
(p≥0.158) (Table 3), shows that the CNS can properly correct balancing problems caused by the
change in body posture. This finding also confirms the hypothesis that bad posture is primarily a
result of the inadequate condition and weakness of the muscles, which children can still correct
with care. The compensatory role of the CNS may occur in the frequency-specific ML MHR para-
meter, which is significantly lower in the case of bad-postured subjects than in healthy subjects
(p= 0.002) (Table 3). This change represents relatively increased motion in the middle-frequency
range (0.3–1 Hz) (Nagymáté & Kiss, 2016b) in the ML direction compared to higher frequencies.
Additionally, the decrement in the SPR parameter, which is a ratio of AP to ML, indicates the
relatively greater degree of motion in the ML direction as the CNS compensates.
A change of LI (Table 2) is clearly shown by the fact that the LDD value—which is the difference
between the loadings of the two sides—increased significantly (p= 0.021) (Table 3). As a result of
altered inclination caused by bad posture, the symmetrical load between the two sides is over-
turned, and the load on one side is significantly increased. This draws attention to the fact that as a
result of bad posture, an asymmetric load develops, which further deteriorates muscular balance.
The large number of subjects (347) made it possible to determine exclusion criteria accurately
and to create homogenous groups. The present study is unique because the values of the para-
meters characterizing standing balance were determined according to various criteria in a large
number of children with bad posture. Based on the statistical analysis of the results (Table 3), bad
posture significantly affects only the LDD between the legs (p= 0.021) and the medium–high-
frequency band power ratio in the mediolateral direction (ML MHR) (p= 0.002) of the 17 para-
meters. However, the other 15 time–distance- and frequency-based parameters do not show any
significant differences. Based on this, it cannot be clearly stated that bad posture significantly
worsens standing balance. The (non-significant) differences in most parameters between the two
groups (Table 3) show that standing balance parameters are deteriorating due to muscular
imbalance. The effects of the altered posture are continuously corrected by the CNS, which is
indicated by the significant change in the medio-lateral directional medium–high-frequency band
power ratio (ML MHR) parameter. In addition, changes in the spectral power ratio indicate
increased motion in the mediolateral direction as a result of CNS compensation. A significant
change in LI appears in the significant increase in the LDD parameter. An asymmetric load
between the two sides may further degrade muscular imbalance, so correcting it is an important
task of physiotherapy.
The limitation of this study was the fact that the examinations were not performed during a
single leg stance with eyes open and closed, as well as during a bipedal stance with closed eyes
due to accident prevention considerations.
5. Conclusions
There is no clearly significant degradation of postural control in children with bad posture, as
the effects of altered posture are continuously corrected by the CNS. Some differences could
be found in postural control, but these deviations are weakly justified. Due to bad posture,
Nagymáté et al., Cogent Medicine (2018), 5: 1503778
https://doi.org/10.1080/2331205X.2018.1503778
Page 9 of 12

the asymmetric load between the two sides may further degrade muscular imbalance. The
correction of bad posture is an important task of physiotherapy, which should improve the
posture and balance.
Acknowledgements
The authors would like to express their gratitude to phy-
siotherapists Ildikó Nagy and Gábor Szabó for their valu-
able work on the biomechanical measurements, as well
as to Ervin Rudner, MD, for his selfless assistance in clinical
practice.
Funding
This work was supported by the Hungarian Scientific
Research Fund OTKA [K115894] and BME-Biotechnology
FIKP grant of EMMI (BME FIKP-BIO).
Author details
Gergely Nagymáté
1
E-mail: nagymate@mogi.bme.hu
ORCID ID: http://orcid.org/0000-0002-3327-5049
Mária Takács
2
E-mail: rtakacsmaria@gmail.com
Rita M. Kiss
1
E-mail: rikiss@mail.bme.hu
1
Department of Mechatronics, Optics and Mechanical
Engineering Informatics, Budapest, University of
Technology and Economics, Hungary.
2
Department of Orthopedics, MÁV Hospital Szolnok,
Verseghy Street 6-8, Szolnok 5000, Hungary.
Supplementary material
Supplementary material for this article can be accessed
here.
Citation information
Cite this article as: Does bad posture affect the standing
balance?, Gergely Nagymáté, Mária Takács & Rita M. Kiss,
Cogent Medicine (2018), 5: 1503778.
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