The Correlation between Body Mass Index, Maximum Inspiratory

Pressure, and Vital Capacity in Elementary School Children

Virna Agustriani

, Anitta Paulus

, Tresia Tambunan

Department of Physical Medicine and Rehabilitation, Dr. Cipto Mangunkusomo General Hospital,

University of Indonesia, Jakarta, Indonesia

Department of Physical Medicine and Rehabilitation, Persahabatan Hospital., Jakarta, Indonesia

Keywords: Inspiratory Muscle Strength, Body Mass Index, Vital Capacity.

Abstract: This study aimed to assess the correlation between Body Mass Index (BMI), Maximum Inspiratory Pressure

(MIP) and Vital Capacity (VC) of elementary school children aged 8-12 years old. A cross sectional study

was conducted to measure BMI, MIP, and VC among children residing in Central Jakarta. Exclusion criteria

included a history of surgery in the chest area, neuromuscular disease, and cardiorespiratory problems. 27

subjects, who were eligible for the study, were divided into two groups, classified as normal or abnormal

BMI group. MIP and VC were measured by digital manometer and spirometer respectively. Data were

analyzed by the T-test and Pearson test. The differences of MIP and VC value in the normal and abnormal

BMI group was found tend to higher of MIP in normal BMI group, i.e. 75.71 + 12.83 and 70.55 +16.4, and

higher of VC in normal BMI group, i.e. 1.69 ± 0.27 amd 1.91± 0.47(p=0.025). There was moderate positive

correlated between BMI and VC (r= 0.652, p<0.001), in contrast between BMI and MIP (r= 0.352, P =

0.071). Children with normal BMI has higher VC, while the higher of BMI has correlation with the higher

of VC.

1 INTRODUCTION

Childhood is the age span ranging from birth to

adolescence. In this stage, children’s growth and

development status were rapidly emerging. The

growth of the children can be measured by the Body

Mass Index (BMI) as a reflection of their nutritional

status. Nutritional Status divided by 3

classifications such as normal, underweight,

overweight, and obesity. In 2012, it was reported

that all over the world, more than 40 million

children aged ≥5 years were overweight or obese.

(da Jung and Schivinski, 2014)

Nowadays, obesity has become one major health

issue in the world. Overweight and obesity has

increased rapidly in populations and associated with

several complications, such as hypertension,

diabetes, psychosocial disorders which related to

acceptance in the group, or removal of group

activities, sleep apnea, and increased ventilatory

demand. Obesity increased ventilatory demand

which often accompanied by fatigue upon exertion

and limitations to carry out some activities of daily

living. (da Jung and Schivinski, 2014), which will

lowered affected children’s quality of life.

According to the physiology of respiratory

function, obese people may have an altered

ventilation distribution, with the risk of manifesting

gas exchange abnormalities. There will be a

reduction in spirometry test variables of functional

residual capacity and expiratory reserve volume due

to the presence of adipose tissue accumulation

around the thoracic and abdominal surfaces.

Furthermore, obesity will induce fat deposition in

compartments, reduction of pulmonary compliance,

damage to mechanical ventilation due to increased

respiratory effort, potential inefficient respiration,

and decreased ability to generate strength for

breathing. On the other hand, underweight children

have smaller muscle mass, which may affect the

strength of respiratory muscle and diminishing lung

capacity.

Respiratory function was influenced by the

skeletal structure, respiratory muscle strength, and

lung volume. Respiratory muscle strength can be

Agustriani, V., Paulus, A. and Tambunan, T.

The Correlation between Body Mass Index, Maximum Inspiratory Pressure, and Vital Capacity in Elementary School Children.

DOI: 10.5220/0009089502850289

In Proceedings of the 11th National Congress and the 18th Annual Scientiﬁc Meeting of Indonesian Physical Medicine and Rehabilitation Association (KONAS XI and PIT XVIII PERDOSRI

2019), pages 285-289

ISBN: 978-989-758-409-1

285

measured by Maximum Inspiratory Pressure (MIP)

and Maximum Expiratory Pressure (MEP). MIP

interpreted the strength of diaphragm and inspiratory

muscle, meanwhile, MEP interpreted the strength of

the abdominal muscles and expiratory muscles.

(Heinzmann-Filho et al., 2012)

Nevertheless, it is still controversial that obesity

may generate a reduction in lung volumes and

increased airway resistance. Many studies are

conducted to seek any relationship between obesity

and respiratory muscle strength, although without

showing any conclusive results. Studies with

children samples were also limited. (da Rosa et al.,

2017). A study by Redding (2017) showed that there

was a relationship between MIP and VC in early

scoliosis children, but with no differentiation for

each BMI classification. (Redding et al., 2017)

Hence, in this study, we would like to assess the

correlation between various BMI status and

respiratory muscle strength along with vital capacity.

We hypothesized that abnormal BMI will be

lowering the MIP value and vital capacity (VC).

2 METHODS

A cross sectional study was conducted to analyze the

Body Mass Index (BMI), Maximum Inspiratory

Pressure (MIP), Vital capacity among healthy

elementary children residing in Central Jakarta. The

study was ethically approved by the Research Ethics

Department of Cipto Mangunkusumo Hospital,

Faculty of Medicine University of Indonesia. The

inclusion criteria included children aged 8-12 years,

meanwhile, the exclusion criteria included a history

of surgery in the chest area and upper abdomen,

chest deformities, history of neuromuscular disease,

and other cardiorespiratory problems.

The subjects were screened and their

anthropometric status was measured. The body

weight was evaluated by digital portable device,

body height was measured with shoorboard and BMI

was calculated by dividing the weight by height in

meters squared (kg/m2). It was then categorized into

normal BMI and abnormal BMI based on the criteria

legalized by the Ministry of Health of Indonesia.

Maximum Inspiratory Pressure was measured by

a digital manometer (microrpm) with muller’s

maneuver. First, the subject was asked to inhale as

much as possible meanwhile the maximum

inspiration was measured in MIP. This examination

was repeated 3 times and the highest value was

recorded along with the difference between the

highest and the lowest result <20%. (Heinzmann-

Filho et al., 2012). Vital capacity was measured by a

spirometer. A comparison of MIP and Vital capacity

between groups were analyzed by the Unpaired T-

test and Pearson correlation test.

3 RESULTS

There were 27 subjects were enrolled in this study,

19 boys and 8 girls. The mean age was 9.67 ± 0.17

years old. 7 subjects with normal BMI and 20

subjects with abnormal BMI. Mean of BMI for the

obesity, overweight and underweight groups was

25.43±0.76, 21.33±0.69 and 13.67±0.07

respectively.

MIP values in elementary school children within

normal BMI was higher than in the abnormal BMI

group (75.71 ± 12.83 and 70.55 ±16.41), but with no

significant difference (p=0.358). Vital capacity in

children with normal BMI and abnormal BMI was

not statistically significant (1.69+ 0.27 vs 1.91 +

0.47, p=0.025).

Table 1. Comparison of BMI with MIP and VC.

Normal BMI

n= 7

Abnormal

BMI

n= 20

Value

MIP 75.71 ± 12.83 70.55 ±16.41 0.358

VC 1.69 ± 0.27 1.91± 0.47

0.025

*T test

BMI, body mass index; MIP, maximum inspiratory

pressure; VC, vital capacity. *P <0.05.

The BMI value had a positive correlation with

vital capacity (r= 0.652, p<0.001), but showed

insignificantly very weak positive correlation with

respiratory muscle strength (r=0.124, p=0.539). MIP

value had an insignificantly weak correlation with

lung vital capacity.

Table 2. Correlation between MIP, BMI, and VC.

Pearson’s

correlation

coefficient

p-value n

BMI-

MIP

0.124 0.539 27

BMI –

0.652 0.000* 27

MIP -

0.352 0.071 27

*pearson test

KONAS XI and PIT XVIII PERDOSRI 2019 - The 11th National Congress and The 18th Annual Scientiﬁc Meeting of Indonesian Physical

Medicine and Rehabilitation Association

286

4 DISCUSSIONS

Obesity affects the respiratory system by several

mechanisms, including direct mechanical changes

due to fat deposition in the chest wall, abdomen, and

upper airway. The function of the respiratory

muscles may be impaired with increasing obesity,

possibly due to the load imposed on the diaphragm.

The observed dysfunction of the respiratory muscles

can be partially explained by the increased resistance

imposed by the presence of excess fatty tissue on the

chest and abdomen, which causes mechanical

disadvantage to these muscles. (Mafort et al., 2016)

Respiratory muscle strength can be assessed by

measuring MIP and MEP. (Mafort et al., 2016) In

obese individuals, both MIP and MEP may be

reduced. The impairment of respiratory muscles is

multifactorial; there are ineffective muscle

contractions and premature fatigue, indicating that

the reduction in MIP and MEP may be due to

distension of the diaphragmatic muscles, increased

respiratory effort, and ineffective muscle

biomechanics caused by fat deposition in the

thoracic and abdominal regions. (Chlif M,

Keochkerian D, Choquet D, Vaidie A, 2009; Arena

R, 2014)

In the present study, we found that MIP values in

elementary school children with normal BMI are

higher than abnormal BMI values (75.71 + 12.83

and 70.55 +16.41, p=0.358). Weak positive

correlation with respiratory muscle strength

(r=0.124, p=0.539) was also revealed in our study as

in the previous study. (Rosa and Schivinski, 2014)

Another study has shown an increment of MIP in the

adult obese group compared to the non-obese group.

They explained there was an increment in thoracic

impedance in obese adults due to fat deposition on

the diaphragm. This may reduce the Functional

residual capacity (FRC) and it requires high

ventilation, hence it increases the respiratory force

and pressure during ventilation. (Shinde et al., 2017)

A negative correlation was also revealed from the

study comparing MIP of obese women before and

after gastrectomy surgery. (Weiner et al., 1998) A

preliminary study used skeletal muscle mass index

(SMI) correlated to respiratory muscle in sarcopenia

patients. muscle index was determined as skeletal

muscle mass, it was measured by bioelectrical

impedance analysis. This study has shown positive

correlations between MIP and SMI. This study

probably more accurately predicts respiratory

muscle function than BMI alone, but still, need

further investigation. (Ro et al., 2015)

Individuals with obesity presented with a

reduction in lung volume and capacity as compared

to healthy individuals, which means that the

presence of a restrictive respiratory pattern

associated with obesity. There are several potential

mechanisms by which BMI might lead to reduce

VC, which was broadly divided into mechanical and

inflammatory. (Liu et al., 2017)

Visceral adipose tissue influences circulating

concentrations of interleukin-6, tumor necrosis

factor alpha, leptin, and adiponectin, which are

cytokines that may act via systemic inflammation to

negatively affect pulmonary function.(Paralikar et

al., 2012) As BMI continues to rise, the fat content

rises gradually, Intra-peritoneal fat deposits and

accumulation may impede the descent of the

diaphragm during inspiration, which would affect

the lung's breathing function.(Liu et al., 2017)

Vital capacity in children with normal BMI and

abnormal BMI was insignificant difference (1.69+

0.27 vs 1.91 + 0.47, p=0.358). However, BMI has

positive correlation with vital capacity (r= 0.652,

p<0.001). The previous study in Italian school

children has shown a positive correlation between

FVC and body weight. They hypothesized that

weight behaves as an index of body growth and in

turn increases the lung volume. In addition, BMI

may not truly reflect adiposity, rather a simpler

epidemiological measure. (Cibella et al., 2015) A

study conducted in children 8-12 years of age

reported children with higher BMI and larger waist

circumference have the higher vital capacity.

(Bekkers et al., 2015) A similar result also proved

through a meta-analysis that there was no significant

association between BMI and vital capacity in

children and was negatively associated with FVC in

adults. There was a slight increase in FVC in

overweight or obese children but also increased risk

of airway dysanapsis- a phenomenon in which an

asymmetrical growth of the lungs and airways lead

to higher FEV1 and FVC but with a more

pronounced effect on FVC. Nevertheless,

overweight and obese adults have lower vital

capacity, this is probably due to BMI in adult only

represents adiposity and not growth. (Forno et al.,

2018)

We found only weak correlation between MIP

and lung vital capacity. Previous studies in early-

onset scoliosis children with no muscle weakness,

MIP%, and MEP% were significantly correlated

with FVC. (Redding et al., 2017) Another study

showed anterior pelvic tilt position muscle

alignment was better for increasing vital capacity,

however no specific measurement of respiratory

The Correlation between Body Mass Index, Maximum Inspiratory Pressure, and Vital Capacity in Elementary School Children

287

muscle strength was done by the researcher. (Jang

and Lee, 2015) In neuromuscular disorder, FVC has

been used to evaluate an intervention in patients.

However, the result may also be affected by factors

that are independent of respiratory muscle

dysfunction and measuring MIP could be a

complement to spirometry. Furthermore, MIP may

be more sensitive than FVC for assessing respiratory

muscle function since spirometry test results are

influenced by many factors. (Schoser et al., 2017)

5 CONCLUSIONS

Children inspiratory muscle strength was influenced

by their anthropometric status, as it is better in

children with normal BMI. Obesity caused

mechanical compression of the diaphragm, resulting

in increased pulmonary resistance and reduction of

pulmonary muscle strength.

Higher BMI increased the dimensions of the lung

which is described by increased VC. In this study,

there was no correlation between BMI and children's

lung compliance. Further research with more

subjects was recommended to produce a better result

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