Table 2 Descriptive analysis of the articles included in the systematic review

Yao et al. [10] (2017) - China

To evaluate the effect of excess weight on lung function and FeNO in Asian children with a focus on changes in atopy

Smoking (Analysis was performed including and excluding individuals with asthma, but this was not an initial exclusion criterion)

Prospective cohort

1717 Asian children aged 5 to 18 years

Spirometry (Spiro Lab II, Medical International Research, Roma, Italy) FeNo (CLD 88 NO analyzer^®, Evo Medics, Duernten, Switzerland)

Spirometry: ATS – position not mentioned FeNO: ATS and ERS - position not mentioned

FVC, FEV₁, FEV₁/FVC, PEF, FEF_25–75%, FeNO

There were associations (+) of z-score of BMI with FVC, FEV₁, PEF and FEF_25–75% and (−) with FEV₁/FVC and FeNO. The associations occurred for the variables in the analysis with the entire group and excluding individuals with asthma

Excess weight changes lung volume and flow in a disproportionate manner, which reflects in the increase in FVC, FEV₁, PEF and FEF_25–75%, and reduction in FEV₁/FVC

Peng et al. [11] (2016) - China

To evaluate whether weight index is associated with high BP, reduced FVC, dental caries and low vision, as well as whether nutritional status can predict diseases in schoolchildren

Yes (individuals with chronic or infectious diseases, e.g., cardiovascular, renal, hepatic, diarrhea, pneumonia, upper respiratory tract infection and influenza)

Cross-sectional

12,297 children aged 6 to 18 years

Spirometry (model not mentioned)

Standardized instrument not mentioned - standing

FVC

Group 6 to 12 years - males compared to females: higher weight, WC, BMI, SBP, FVC, low weight, overweight and obesity, FVC/weight; and lower SAH and low vision. Group 13 to 18 years - males: higher weight and height, WC, BMI, SBP, FVC, FVC/weight, prevalence of underweight, overweight, obesity, abdominal obesity and poor FVC/weight; and lower DBP, SAH, caries and low vision. Group of individuals with underweight had the lowest value of WC, SBP, FVC and visual acuity; and better FVC/weight. Group of individuals affected by obesity presented higher value of WC, SBP, DBP and FVC; and lower number of caries and FVC/weight. Children with overweight and obesity were at increased risk of high BP and poor FVC/weight when compared to children with normal weight, while undernourished children were at higher risk of caries, and in both groups, there was a higher risk of low vision

Inadequate nutritional status was associated with BP, FVC, caries and visual acuity. The prevalence of common diseases in school-aged children is greater in children with altered weight. Thus, weight index is a potential marker to predict some diseases, reinforcing the importance of maintaining weight in the prevention of diseases in schoolchildren. However, the causal relationship and physiological mechanisms to explain the changes need to be further studied

LoMauro et al. [12] (2016) - Italy

To verify whether the thoracoabdominal volume of male adolescents with obesity during exercise has specific characteristics to deal with the increasing ventilatory demand and to investigate whether a short period of multidisciplinary program for weight loss, including respiratory muscle resistance training, can modify the geometry and volume of the rib cage

Not mentioned

Prospective and intervention

11 male adolescents (Tanner 3 to 5), with standard deviation of BMI > 2, in relation to the Italian standards

Spirometry (MedGraphics CPX/D, Medical Graphics Corp., Saint Paul, Minn., USA) and OEP (Smart System BTS, Milan, Italy)

Spirometry: ERS – standing

OEP: Standardized instrument and position not mentioned

FVC, FEV₁, FEV₁/FVC, PEF, total and compartmental volume in FRC and TLC, TV, RR, MV

FEV₁/FVC was greater than 80% predicted in the individuals, indicating the absence of OVD, but with a possible indication of a restrictive pattern. After the intervention, there was an improvement in the absolute and predicted values of FVC, and a reduction in IC of the lung and abdominal rib cage was observed

Hyperinsulflation of the abdominal rib cage occurs during incremental exercise from moderate intensity to peak intensity in order to recruit lung volume, being an adaptation of the ventilatory dynamics to deal with the overload of the chest wall due to obesity, optimizing the synergism between the diaphragm and the abdominal musculature. The system starts to function at high volume to optimize lung compliance. After training, there was reduction in abdominal load, pulmonary recruitment and thoracic cavity volume, improvement of physical performance, reduction in dyspnea and delay in dynamic hyperinsulflation of the abdominal thoracic cavity without ventilatory and metabolic requirements, which contributes to the improvement of exercise tolerance and inhibition of the cycle of inactivity and weight gain

Özgen et al. [13] (2015) - Turkey

To evaluate the relation between lung function tests and functional capacity during exercise in children with obesity

Yes (syndromic children with endocrine conditions added to obesity, history or evidence of cardiovascular, respiratory or hepatic metabolic diseases)

Cross-sectional

74 children with obesity (13.4 ± 2.3 years) and 36 children without obesity (12.7 ± 1.9 years)

Spirometry (Spiro Lab III, MIR^®, Rome, Italy)

ATS - position not mentioned

FVC, FEV₁, FEV₁/FVC, FEF_25–75%, PEF

Lower FEV₁, FEF_25–75% and distance covered in the 6MWT in the group with individuals affected by obesity. There was a (−) correlation of the distance covered in the 6MWT with the standard deviation of the BMI

Pulmonary and functional exercise capacity were lower among individuals with obesity

Kongkiattkul et al. [14] (2015) - Thailand

To evaluate the correlation between obesity indexes (anthropometry and bioimpedance) and lung function parameters and to identify whether the indexes correlate with abnormalities in lung function of children and adolescents with obesity

Yes (children with respiratory or neuromuscular diseases that could affect lung function assessment, respiratory infection within 2 weeks before the test, and inability to perform the tests)

Cross-sectional

45 individuals with obesity and aged 8 to 18 years

Spirometry and Body Plethysmography (Vmax 6200 Autobox™ diagnostic system - SensorMedics, Yorba Linda, CA, USA)

Standardized instrument and position not mentioned

FVC, FEV₁, FEV₁/FVC, FEF_25–75%, FRC, TLC

64.4% of the individuals with obesity had a reduction in FRC, 7% had OVD (FEV₁ < 80% and/or FEF_25–75% < 70% of predicted) and 2% RVD (TLC < 80% of predicted). There was a (−) correlation of FRC with BMI z-score, waist-height ratio, % of fat mass, fat mass index and % of fat in the trunk

FRC below normal was the most frequent alteration in lung function in the group of individuals affected by obesity. BMI z-score and obesity indexes that correlate with the central distribution of fat (waist-height ratio, % of fat mass, fat mass index and% of fat in the trunk) had a (−) correlation with FRC. The indices may help identify the reduction in FRC and should be used to assess obesity. The fat mass index > 17 kg/m² may be a screening tool in obesity, risk for low FRC, and the need for respiratory care to prevent pulmonary complications

Ferreira et al. [15] (2014) - Brazil

To assess the influence of obesity on physical and lung function of children and adolescents with obesity and to associate the variables with a control group

Yes (chronic and/or respiratory diseases, neurological and/or physical limitations)

Cross-sectional

38 individuals with obesity and 39 healthy individuals aged 5 to 17 years

Spirometry (CPFS/D - MedGraphics Saint Paul, Minnesota, USA)

ATS and ERS - standing

FVC, FEV₁, FEV₁/FVC, FEF_25%, FEF_50%, FEF_75%, FEF_25–75%, PEF, ERV

The group of individuals affected by obesity showed lower FEV₁/FVC, FEF_25%, FEF_50%, FEF_75%, FEF_25–75%, PEF, and distance covered in the 6MWT. Males were associated with lower FEF when compared to females in both groups

Changes in Spirometry associated with FEF alterations suggested obstructive change in 36.8% of individuals with obesity. The changes in lung function did not present a direct correlation with the performance in the 6MWT, but with the perception of effort in the exercise

Rastogi et al. [16] (2014) – United States of America

To investigate the association between total fat, trunk fat and metabolic abnormality with lung function of a sample of minority urban adolescents

Smoking [overweight individuals, chronic inflammatory conditions (rheumatologic, endocrine, gastrointestinal, or renal – study does not mention respiratory conditions)]

Cross-sectional

168 Hispanic and African adolescents aged 13 to 18 years (82 with obesity and 86 normal weight adolescents)

Spirometry and Body Plethysmography (SensorMedics, Yorba Linda, California)

ATS - position not mentioned

FVC, FEV₁, FEV₁/FVC, FEF_25–75%, TLC, RV, RV/TLC, ERV, FRC, IC

Individuals had Spirometry levels within the parameters of normality. However, when they were characterized by BMI and WC, adolescents with total and trunk adiposity had lower % of predicted rates for pulmonary volumes, including RV, RV/TLC, ERV and FRC and higher IC. In the univariate analysis, adiposity and metabolic abnormality were predictors of lung function; high HOMA-IR predicts reduction in FEV₁/FVC, RV, RV/TLC, ERV, FRC; and increased IC. Low HDL predicts low FEV₁/FVC and RV/TLC; and high IC. Patients with asthma presented lower FEV₁/FVC, without changes in lung volume. ERV was lower in males than in females. In the multivariate analysis adjusted for total fat and trunk, increasing HOMA-IR was a predictor of lower FEV₁/FVC and ERV, and low HDL had a (+) correlation with FEV₁/FVC. Total adiposity was predictor for IC, FRC, RV and RV/TLC; and adiposity in the trunk, RV and FRC. Among the covariates, asthma was a predictor for FEV₁/FVC, females for ERV, and Hispanics for ERV and IC

Mechanical overload caused by adiposity and some metabolic abnormalities (HOMA-IR and HDL) were independent predictors of adolescent lung function deficit. The findings suggest that the early assessment of metabolic risk in children affected by obesity may help identify individuals at risk of developing lung diseases. However, studies are needed to understand the influence of the pathophysiology of obesity on lung function

Faria et al. [17] (2014) - Brazil

To investigate lung function response during exercise in adolescents with non-morbid obesity and without respiratory diseases

Yes (history of acute or chronic respiratory diseases, thoracic or skeletal deformity, heart diseases and congenital diseases)

Cross-sectional

92 adolescents aged 10 to 17 years – 47 with obesity (23 males) and 45 HC (21 males)

Spirometry (CPFS/D - MedGraphics Saint Paul, Minnesota, USA), FMR (Gerar^®)

Spirometry: ATS and ERS - position not mentioned

Manuvacuometry: Standardized instrument not mentioned - sitting

FVC, FEV₁, FEV₁/FVC, IC, ERV, VC MVV, MIP, MEP

Baseline BP and HR were higher among individuals with obesity, while SpO₂ was lower. MVV, FVC and FEV₁ were lower in males with obesity when compared to HC. IC in the group of females + obesity was higher than in the group of females + control. ERV was lower in both sexes among individuals with obesity when compared to controls. There were no differences in lung function before and after exercise. RMS showed differences between the sexes, but not between individuals with obesity and HC

The distribution of body fat alters lung function in a sex-dependent manner among individuals with obesity and does not change after exertion

Davidson et al. [18] (2014) - Canada

To investigate the relationship between age, sex and BMI and lung volume of healthy individuals aged 6 to 17 years

Yes (children with cardiorespiratory or ribcage diseases, asthma and individuals with reversible obstruction in spirometry)

Retrospective

327 healthy individuals divided into 4 groups: underweight (pBMI < 5), normal weight (pBMI between 5 and 85), overweight (pBMI between 85 to 95) and individuals with obesity (pBMI ≥95)

Spirometry, Body Plethysmography [SensorMedics (Northridge, CA) Vmax 22 system with volume measurement by the 6200 autobox and Vmax Legacy Plethysmography software (Viasys, Yorba Linda, CA)]

ATS - position not mentioned

FEV₁, FVC, FEF_25–75%, TLC, VC, FRC, ERV, RV, D_LCO

Individuals with obesity showed lower values in the predicted % of FRC and ERV. RV was lower in the groups of individuals with overweight and obesity. Individuals with low weight had lower FVC and RV. In the group of individuals with obesity, there was lower FEV₁/FVC. Additionally, there was a (+) linear association of the BMI z-score with the % of predicted of FVC, VC and D_LCO and (−) linear association of the BMI z-score with the % predicted of FRC, ERV, RV and absolute value of FEV₁/FVC

Obesity was related to lower lung volume in children and adolescents. Changes in lung function may result in worsening respiratory symptoms and reduced functional capacity. Thus, there is a need to develop and implement effective strategies to prevent and manage obesity in childhood and adolescence

Gibson et al. [19] (2014) - Australia

To evaluate (i) whether children and adolescents with overweight or obesity can be submitted to submaximal exercise; (ii) respiratory limitations during exercise in children and adolescents with overweight and obesity compared to the control group

Yes (children with chronic cardiorespiratory problems or if it was not safe to exercise due to medical and/or musculoskeletal conditions)

Cross-sectional and prospective

26 individuals with obesity and 25 HC aged 10 to 18 years

Spirometry (SensorMedics, Yorba Linda, CA, USA), multi-breath nitrogen wash-out (Vmax 29, hardware and software - Sensormedics)

Spirometry: ATS - position not mentioned

FVC, FEV₁, FEF_25–75%, FRC, TLC, RV

There was no difference between the groups for TLC, FVC, FEV₁ and FEF_25–75%. However, the groups with individuals affected by overweight and obesity presented lower z-scores of the FRC and RV. The expiratory flow during the submaximal exercise was associated with the variables of weight (z-score BMI, weight and % of fat mass) and FEF_25–75%

Young individuals with overweight and obesity may perform submaximal tests, and they tend to have a higher limitation of expiratory flow during submaximal exercise than healthy children. The use of compensatory breathing strategies allows overweight individuals to exercise at this intensity without feeling short of breath

Rio-Camacho et al. [20] (2013) - Spain

To investigate the left ventricular mass (echocardiography) of children with obesity, with and without metabolic syndrome; to evaluate the association between the level of adipokine and circulating cytokine and the alteration of left ventricular mass and Spirometry; and to determine the best variable to predict cardiovascular risk

Yes (children with chronic diseases and/or Tanner = 5 (to avoid sexual dysmorphism of adipokines analyzed at this stage)

Cross-sectional and descriptive

41 individuals with obesity and over 8 years old (20 with metabolic syndrome criterion)

Spirometry (Frow Screen - Jaegger^®)

ATS - position not mentioned

FVC, FEV₁, FEV₁/FVC, FEF_25–75%

MCP-1, LAR and CRP were higher in the presence of metabolic syndrome. There were no differences between the groups, with and without metabolic syndrome, for Spirometry and left ventricular mass

Obesity with metabolic syndrome has a higher degree of inflammation, and CRP is the best predictor of vascular risk. However, left ventricular mass and Spirometry were not influenced by the chronic inflammatory state in children and adolescents with obesity

Berntsen et al. [21] (2011) - Norway

To evaluate whether lung function measured in standing position is higher in children with overweight and obesity, when compared to the sitting position

The study does not mention respiratory conditions, only organic causes or diseases that may lead to obesity, conditions that may restrict the ability of being physically active and the use of medication that acts on growth or weight gain

Randomized and cross-over

115 individuals with overweight and 92 individuals with obesity aged 7 to 17 years

Spirometry (Vmax Series, SensorMedics, Yorba Linda, CA, USA)

ERS - sitting and standing

FVC, FEV₁, FEF_50%, FEV₁/FVC, PEF

15% of the patients had asthma. Females, when compared to males, showed higher value of FEV₁ and FVC. FEV₁, FVC and FEF_50% were higher in Spirometry performed in the sitting position when compared to the evaluation in the standing position. In the linear regression analysis, the % of BMI, diagnosis of asthma, use of corticosteroids and sex were associated with changes in FVC, FEV₁, FEF_50% and PEF

FVC, FEV₁ and FEF_50% were higher in the sitting position when compared to the standing position. However, the increase had little clinical significance. In this way, the sitting position is the most appropriate posture to perform forced expiratory flow-volume maneuver

Chen et al. [22] (2009) - Canada

To evaluate WC as a predictor of lung function markers and to compare it with BMI in children and adolescents

Not mentioned (8 participants were excluded because they presented reduced lung function value and low reproducibility)

Cross-sectional

718 individuals aged 6 to 17 years

Spirometry (MedGrahics System CPFS - Medical Graphics Corporation, St. Paul, MN, 1992)

ATS - position not mentioned

FVC, FEV₁, FEV₁/FVC

WC had a (+) correlation with FVC and FEV₁, and (−) correlation with FEV₁/FVC. On average, 1 cm increase in WC was associated with an increase of 7 mL in FVC and 4 mL in FEV₁. The assessment of height showed no changes in the association between WC and lung function. However, by adding body weight, the 1 cm increase in WC was associated with an increase of 4 mL in FVC and 2 mL in FEV₁

The association (−) of WC and FEV₁/FVC may be related to adiposity and/or lower predictability of FEV₁ in relation to FEV₁/FVC in children. Thus, overweight and obesity is likely to be associated with reduced lung function in childhood

Kalhoff et al. [23] (2011) - Germany

To investigate whether overweight or obesity are associated with abnormalities in IOS in a random sample of pre-school children aged 6 years

Not mentioned

Cross-sectional

518 preschoolers aged 6 years

IOS (MasterScreen IOS - CareFusion, Höchberg, Germany)

ATS and ERS - position not mentioned

Airway resistance at 5 Hz and pulmonary reactance at 5 Hz

The study found no differences in resistance and reactance at 5 Hz in children with high BMI

In children aged 6 years, abnormalities in IOS were not associated with increased BMI. IOS requires little cooperation to have the test performed, unlike Spirometry. Therefore, this technique enables the analysis of pulmonary development with the age by measurements in series, from childhood to adolescence

Gundogdu et al. [24] (2011) - Turkey

To evaluate the effects of obesity on lung function and to define the relation of BMI as independent variable and PEF as dependent

Yes (children who had major dysfunctions - cardiac, respiratory, renal or hematological or those with asthma symptoms)

Cross-sectional

1439 children aged 6 to 14 years

PFE (Mini Wright Peak Flow)

GINA, 2005 - standing

PEF

Simple multiple linear regressions showed reduced PEF associated with an increase in BMI category. PEF was lower in the group of individuals affected by obesity when compared to individuals without obesity

PEF was lower in children with obesity than in children with normal weight. As PEF is an indicator of pulmonary airflow resistance, there was an increase in respiratory resistance in children with obesity. The association of high BMI with reduced PEF indicated that obesity is a risk factor for reduced airflow and lung function. Reduced prevalence of asthma may be a result of the patients´ awareness and obesity prevention, i.e., prevention of obesity can reduce respiratory symptoms

Ferreira et al. [25] (2017) - Brazil

To evaluate lung function of children and adolescents with obesity (without asthma) by Spirometry and VC and to compare them to HC of the same age group

Yes (children with a history of respiratory diseases – asthma, obstructive sleep apnea or chronic obstructive pulmonary disease)

Cross-sectional

38 individuals with obesity and 39 HC aged 5 to 17 years

Spirometry (CPFS/D - Medical Graphics Corp., MN, USA and software Breeze PF 3.8 - Medical Graphics Corp., MN, USA) and VolC (CO2SMO - Dixtal, São Paulo, Brazil)

Spirometry: ATS and ERS - position not mentioned VolC: Standardized instrument not mentioned - sitting

FVC, FEV₁, FEV₁/FVC, FEF_75%, FEF_25–75%, ERV, MV, MV_alv, TV, TV_alv, DSV, DSV/TV, IC EtCO₂, VCO₂, RR, SpO₂, Slp₂, Slp₃, Slp₂/TV, Slp₃/TV

The lowest z-score of FEV₁/FVC, FEF_75% and FEF_25–75% occurred in the group of individuals with obesity, and 36.8% of individuals affected by obesity had FEF_25–75% lower than 70% (OVD by flow), and changes did not occur in the control group. In CV, the group of individuals with obesity showed lower DSV/TV and Slp₃/TV. In the linear regression, the BMI z-score influenced FVC, FEV₁/FVC, FEF_75%, FEF_25–75%, TV_alv, DSV/TV, VCO₂, Slp3 and Slp3/TV. There was no response to BD among individuals with obesity. In the division by age group (5 to 11 years or > 11 years) there were changes of FEV₁/FVC in both groups and only in the older individuals for expiratory flow and pulmonary volume

Even without the diagnosis of asthma by clinical criteria and without response to BD, individuals with obesity show lower FEV₁/FVC and FEF, indicating an obstructive process. In CV, in the group with individuals with obesity, there was higher TV_alv, with no alteration in ventilation homogeneity, suggesting that these individuals have altered flow, but no changes in lung volumes

Del-Rio Navarro et al. [26] (2013) - Mexico

To compare bronchial hyperreactivity by the methacholine challenge testing in Mexican children with normal weight. In addition, to associate the group with normal weight with children with obesity or morbid obesity

Yes (underweight children, chronic respiratory diseases – including asthma and rhinitis, acute respiratory infection in the last month, endocrine diseases, dysmorphic dysfunction or exposure to tobacco)

Cross-sectional

229 children aged 10 to 18 years (40 – normal weight, 116 – with obesity and 73 – with morbidly obesity)

Spirometry (Vmax, Sensor Medics, Anaheim, CA), methacholine challenge testing (provocholine, 100 mg, Methaparm, Inc., Coral Springs, Fl) performed with dosimeter (Mark Salter Labs, Arvin, CA)

Spirometry: ATS - sitting

FVC, FEV₁, FEF_25–75%, PEF

In the group with obesity or morbid obesity, there was higher FVC and lower FEF_25–75%, when compared to children with normal weight. Individuals with obesity, when compared with morbidly obese ones, had lower FEF_25–75%. PEF was higher among children with obesity when compared to children with normal weight or with morbid obesity. During the methacholine challenge testing, FEV₁ was lower among children with obesity than in children with morbid obesity, starting from a dose of 0.25 mg/mL up to a dose of 16 mg/mL. In the comparison of group of individuals with normal weight with the group of individuals with obesity, there was higher value of FEV₁ during methacholine challenge testing with 0.25 and 1 mg/mL of methacholine and lower with 4 and 16 mg/mL in the control group

Obesity did not change aerobic responsiveness due to the use of methacholine and studies should be performed to confirm the findings

Spathopoulos et al. [27] (2009) - Greece

To evaluate the effect of obesity on lung function in a cohort of children aged 6 to 11 years and to associate obesity, atopy and asthma

Yes [high or low respiratory infection, exacerbation of asthma in the last 3 weeks, uncontrolled asthma (GINA), congenital heart abnormality, thoracic deformity or neuromuscular diseases]

Cohort

2715 children aged 6 to 11 years, (1978 – normal weight, 357 – with overweight and 300 – with obesity)

Spirometry (Vitalograth 2120)

ATS and ERS - position not mentioned

FVC, FEV₁, FEV₁/FVC, FEF_25–75%

Among overweight individuals, FVC, FEV₁, FEF_25–75% and FEV₁/FVC levels were lower when compared to controls. Although the diagnosis of atopy and asthma is frequent in children with overweight and obesity, there was no difference in lung function in individuals with and without asthma. High BMI was an independent variable to predict reduction in Spirometry (mainly for FEF_25–75%) and a risk factor of asthma and atopy. When separated by sex, high BMI was associated with FVC in females and FEV₁/FVC in males

High BMI is a marker of obesity in children that can be easily measured and can determine the reduction in Spirometry measures, risk of atopy (both sexes) and asthma among females

Jeon et al. [28] (2009) – South Korea

To evaluate the factors that influence lung function in female adolescents, focusing on the hormonal factors of the menstrual cycle and obesity

Not mentioned

Cross-sectional

103 Korean high school children aged 15 to 18 years

Spirometry (Super Spiro, Micro Medical LTD, Kent, UK)

Standardized instrument and position not mentioned

FVC, FEV₁, FEF_25–75%, FEV₁/FVC

FEV₁/FVC was lower in females with obesity, when compared to HC of the same gender. The individuals who were evaluated in the menstrual period had lower FEV₁, FEV₁/FVC and FEF_25–75%

The literature is scarce on the study of asthma, lung function and puberty. In the study, there was a limitation of airflow associated with obesity, allergy, menstrual cycle and sensitization by inhaled allergens. Studies should be conducted to evaluate the relationship between gender hormones, leptin, lung function and asthma

He et al. [29] (2009) - China

To evaluate the relationship of obesity and asthma, asthma symptoms and lung function of Chinese schoolchildren using the definition of overweight and obesity of a Chinese group

Not mentioned

Cross-sectional

2179 children (1138 boys and 1041 girls) aged 8 to 13 years

Spirometry (Minato AS-505 portable electric spirometer - Minato Ltd., Tokyo, Japan)

ATS - sitting

FVC, FEV₁, FEF_25–75%, FEF_75%, FEF_25%

2% of the sample had asthma. Overweight children had higher FVC than in HC. Men with overweight and women with obesity had higher FEV₁ than controls

Lung function was not altered by obesity; however, there was a higher prevalence of respiratory symptoms in individuals with overweight or obesity. Longitudinal studies need to assess the cause-effect relationship between overweight, obesity and lung function

Silva et al. [30] (2011) - Brazil

To assess the onset of EIB in children and adolescents, without asthma and overweight

Yes (acute and chronic lung diseases, cardiopathy, diabetes, musculoskeletal deformity and pain, steroidal and non-steroidal anti-inflammatory medication, symptoms of viral infection (cold or flu) in the last 6 weeks and FEV₁/FVC < 80%, FEV₁ and PEF < 70% of predicted

Cross-sectional

69 school children aged 8 to 15 years (39 children with obesity without asthma and 30 HC without respiratory diseases)

Spirometry (EasyOne^® model 2001 - Zurich, Switzerland) and PFE (Peak flow meter Healthscan^® Personal Best)

ATS - position not mentioned

FEV₁, PEF, FVC, FEV₁/FVC, FEF_25–75%

The prevalence of EIB was 62% in the group of individuals with obesity and 16% in the control group. There was no difference in Spirometry between groups, except for PEF, which was lower in the group of individuals with obesity

PFE was important in EIB diagnosis. Possibly, different etiologies are related to EIB and studies of pathophysiology of the central and peripheral airways and the onset of EIB in children and adolescents with excess weight should be performed

Bekkers et al. [31] (2013) – The Netherlands

To associate WC and BMI with lung function in 8-year-old children

Not mentioned

Cohort

1,106 children aged 7.4 to 9.2 years

Spirometry (Jaeger pneumotachograph - Viasys Healthcare, San Diego, CA)

ATS and ERS - sitting

FVC, FEV₁, FEV₁/FVC

Children with lower or higher WC showed lower FVC and FEV₁ than those with normal WC. Children with low or high BMI had lower FVC and FEV₁ when compared to normal BMI. Following the adjustments for confounding parameters, there were no differences between groups. Males with high BMI had lower FEV₁/FVC when compared to the same sex with normal BMI. After adjustments for BMI, females with higher WC presented lower FEV₁/FVC

In patients aged ~ 8 years, higher BMI or increased WC were not associated with FEV₁ or FVC, demonstrating that this association may change over the course of childhood to adulthood

Assumpção et al. [32] (2017) - Brazil

To compare IOS parameters of children with normal weight, overweight and obesity

Yes (history of wheezing, respiratory diseases, respiratory tract infection in the last 2 weeks prior to assessment, muscle disorder, passive smoker, neurological diseases, asthma and/or allergic rhinitis [ISAAC - ≥ 5 (6 to 9 years) and 6 (10 to 14 years) for asthma and ≥ 4 (6 to 9 years) and 3 (10 to 14 years) for allergic rhinitis]. Visual, auditory or cognitive impairment, and individuals who did not understand the evaluation procedures

Cross-sectional, analytical and comparative

81 children aged 6 to 14 years: 30 – HC, 21 – with overweight and 30 – with obesity

IOS and Spirometry (IOS Jaeger™ - MasterScreen™ IOS, Erich Jaeger, Germany)

IOS: ATS - position not mentioned Spirometry: ATS and ERS - position not mentioned

Z5, R5, R20, X5, AX, Fres, FVC, FEV₁, PEF, FEV₁/FVC, FEF_25–75%

Spirometry markers were within normal range and no differences between the 3 evaluated groups were determined. However, IOS in the group of individuals with obesity presented higher value than in the control group for: absolute value of Z5, and absolute value and % of predicted of R5, Fres and AX. The group with individuals with overweight presented higher value than the control group for % of predicted value of R5, Fres and AX and for absolute Fres

Children with obesity had higher IOS value, which represents obstruction of the airway in comparison with children with normal weight. Some changes occurred among children with overweight

Cibella et al. [33] (2015) - Italy

To investigate the effects of weight on lung function of healthy children in a sample registered in 2 cross-sectional surveys with selected age group

Yes (history of wheezing, night cough or cough due to exercise)

Cross-sectional

2,393 Caucasian individuals aged 10 to 17 years (51.1% boys)

Spirometry (Microloop, Miro Medica, Chatham Maritime, Kent, UK)

ATS and ERS - position not mentioned

FVC, FEV₁, FEV₁/FVC, FEF_25–75%, FEF_25–75% /FVC

In the control of the variables weight, height, age and sex in the multiple linear regression, the weight B coefficient was (+) for FVC and FEV₁, being higher for FVC, and (−) for FEV₁/FVC and FEF_25–75%/FVC. In the division by age group (<  11, 12, 13 and > 14 years), there was a (+) association of the B weight coefficient with FVC and FEV₁ and a (−) association with FEV₁/FVC and FEF_25–75% /FVC (association of FEF_25–75% and B weight coefficient did not occur in the group < 11 years). Among individuals with obesity and overweight, the % of predicted for FVC and FEV₁ was higher and the absolute value of FEV₁/FVC and FEF_25–75%/FVC was lower than in HC

FVC and FEV₁ were positively associated with weight, when corrected for height. However, due to a different magnitude in the effect of weight on FVC and FEV₁, FEV₁ showed a disproportionately smaller growth with weight gain when compared to FVC. Therefore, in individuals with a high BMI, there is a reduction of FEV₁/FVC and FEF_25–75%/FVC, and this change does not depend on respiratory symptoms

Silva et al. [34] (2015) - Brazil

To evaluate the effects of posture on thoracoabdominal kinematics of children with obesity and to compare them with a control group with normal weight

Yes (pulmonary or neuromuscular diseases)

Cross-sectional

35 children aged 8 to 12 years (18 with obesity and 17 with normal weight)

Spirometry (Micromedical Microloop MK8, Kent, England), RMS (digital manometer - MVD Globalmed 300, São Paulo, Brazil), OEP (OEP - BTS Bioengineering, Italy)

Spirometry: ATS and ERS - sitting; maximum respiratory pressure - sitting; OEP: Aliverti and Pedotti, 2003 - sitting and supine

FVC, FEV₁, FEV₁/FVC, MEP, MIP, TV variation, VTRCp, VTRCa, VTAB, VTRCp%, VTRCa%, VTAB%, Ti, Te, MV, RR, TV and θ

MIP, MV and TV were higher among individuals with obesity. The posture influenced TV (total and compartmental). There was higher TV, VTRCp and VTRCa in the sitting position, while VTAB was higher in supine position among children with obesity. TV was more influenced by the compartments VTRCp% and VTRCa% in the sitting position, while VTAB% was higher in the supine position. In addition, VTAB% was higher among individuals with obesity

The study demonstrated that the thoracoabdominal kinematics of children with obesity is influenced by the supine position, with an increase in abdominal contribution and reduction in the contribution of the rib cage to ventilation, suggesting that supine areas of pulmonary hypoventilation may occur. However, the thoracoabdominal kinematics was not different in the sitting position between the groups. Sitting posture is recommended during therapeutic procedures to achieve better distribution of regional rib cage volume and pulmonary ventilation

Torun et al. [35] (2014) - Turkey

To compare lung function in children with normal weight, overweight, obesity or morbid obesity and to evaluate the effects of degree of obesity on lung function

Yes (atopy or chronic lung diseases, asthma or family history of asthma, atopic dermatitis, food intolerance or syndrome)

Cross-sectional

170 individuals (30 – with overweight, 34 – with obesity, 64 – with morbid obesity and 42 – with normal weight) aged 9 to 17 years

Spirometry (MIR, Spirolab III colour, Roma, Italy)

Standardized instrument and position not mentioned

FVC, FEV₁, FEV₁/FVC, FEF_25–75%, PEF

Overweight, obesity and morbid obesity showed lower FEF_25–75% and PEF, when compared to the group of individuals with normal weight

The study considered FEV₁/FVC < 80% of predicted as OVD. Thus, despite the difference, the study did not identify an obstructive abnormality in the group of individuals with obesity or morbid obesity individuals, when compared to controls with normal weight individuals and pointed out that longitudinal studies should investigate the effect of obesity degree and weight loss on lung function among individuals with obesity

Khan et al. [36] (2014) - Canada

To associate anthropometric measures and lung function in children

Not mentioned

Cross-sectional

1583 children aged 6 to 17 years (males: 573 – with normal weight, 216 – with obesity; females: 626 – with normal weight and 168 – with obesity)

Spirometry (Koko)

ATS and ERS - sitting

FVC, FEV₁, FEV₁/FVC, FEV_0,75

There was higher FVC, FEV_0.75 and FEV₁ in males than in females, and the opposite occurred in FEV₁/FVC. When the variable was adjusted according to the sex of the participants, there was association of BMI and WC with residual FVC in males and FVC and residual FEV₁ in females. Both sexes had an inverse correlation of BMI with residual FEV₁/FVC. In the division by body mass, in the individuals with normal weight, there was a (+) effect of the BMI on FVC, FEV_0.75 and FEV₁, and a (−) effect on FEV₁/FVC. WHR had a (+) correlation with FVC and FEV₁ and a (−) correlation with FEV₁/FVC. The WHR presented a (−) correlation with FEV₁/FVC. In children with overweight and obesity, there was a (−) association of WC and WHR with FVC and FEV₁. In this group, there was a (−) correlation of the skinfold of the triceps, biceps, iliac crest and medial calf with FVC, FEV_0.75 and FEV₁, and the same was observed for the subscapular fold and the sum of all folds, adding the association with FEV₁/FVC. In HC, there was a correlation between: (i) triceps skinfold and FVC; (ii) iliac crest fold and FEV₁/FVC; (iii) sum of the 5 folds (triceps, biceps, subscapular, iliac crest and medial calf) and FEV₁/FVC

In males, there was worsening of lung function with overweight. Lung function was altered by abdominal and subcutaneous fat, and skinfolds were more sensitive to measure adiposity when compared to anthropometric data. The best indicator of adiposity in the analysis of lung function in males was the triceps skinfold

Rosa et al. [37] (2014) - Brazil

To evaluate RMS by maximum respiratory pressure in healthy, schoolchildren with overweight and obesity, and to identify whether the anthropometric and respiratory variables are related to the outcomes

Yes (ISAAC)

Cross-sectional

90 school children aged 7 to 9 years (30 – with obesity, 30 – with overweight and 30 – HC

Spirometry (PIKo-1, Spire Health, USA) and RMS (one-way valve digital manovacuometer (MVD 300, G-MED, Brazil)

Spirometry: ATS/ERS - sitting FMR: ATS - sitting

FEV₁, MIP, MEP

There was higher MIP in HC when compared to the others. The correlation of age with FEV₁, MIP and MEP was (+), and of MIP with BMI (−). MIP and MEP correlated with each other and, with less intensity, with the FEV₁. MEP had a (+) correlation with height and FEV₁. In the individual analysis of the groups, there was correlation of age with weight and height, except in the group of individuals with overweight; weight with height and BMI; MIP with age in the HC group, FEV₁ in the group of individuals with obesity and MEP in the 3 groups; MEP with age and height in the HC group and FEV₁ in the 3 groups; FEV₁ with age in the 3 groups, and weight and height in the HC group and in the group of individuals with overweight

Obesity and overweight were associated with lower MIP when compared to HC. There was a correlation between MIP and MEP with age and FEV₁, mainly, obesity. MIP correlated with BMI and MEP with height, mainly in HC. Thus, possibly, the anthropometric variables may influence RMS in children, as well as in the relation between strength and FEV₁

Assunção et al. [38] (2014) - Brazil

To describe pulmonary functional alterations in asymptomatic and overweight children and adolescents

Yes (history of wheezing, cough, chest pain, or known lung diseases)

Cross-sectional and descriptive

59 individuals aged 8 to 18 years (4 – with overweight, 28 – with obesity and 27 – with morbid obesity)

Spirometry (Koko Digidoser - Ferraris Respiratory, Louisville, CO, USA) and helium washout (mass flow sensor Vmax 21) (Viasys Healthcare, Palm Springs, CA, USA)

Spirometry: ATS and Brazilian Society of Pulmonology and Phthisiology - position not mentioned helium washout - Standardized instrument and position not mentioned

FVC, FEV₁, RV, TLC, FEV₁/FVC, FEF_25–75%

30.3% of individuals had TLC < 80% of predicted and 3.5% TLC > 120%. In the sample, 25.5% of the individuals had a (+) response to BD in FEV₁, most of them with morbid obesity. Individuals with (+) response to BD had FEV₁/FVC < than LLN, therefore, OVD. Regarding the use of BD and FVC, 2 individuals had a (+) response. Other findings were: 32.2% of individuals with OVD (15.2% - with overweight or obesity and 16.9% - morbid obesity) 25.4% with RVD (11.8% - with overweight or obesity and 13.5% - morbid obesity), and 6.7% with MVD (3.3% - with overweight or obesity and 3.3% - with morbid obesity). In addition, there was a (−) correlation between BMI with WC and FEV₁/FVC in the MVD group

Asymptomatic respiratory individuals with excess weight had a high prevalence of ventilatory disorders, predominantly OVD. Additionally, there was a (+) response to the BD, higher than that reported in the literature, most frequently in morbid obesity

Van de Griendt et al. [39] (2012) – The Netherlands

To evaluate the effects of weight reduction on lung function in children with morbid obesity in children aged 8 to 18 years

Yes (asthma or regular use of inhaled corticosteroids)

Longitudinal

112 children aged 8 to 18 and with BMI ≥ 30 Kg/m² with comorbidities or BMI ≥ 35 Kg/m²

Spirometry and Body Plethysmography (MasterScreen PFT + body box - Jaeger Viasys, Wuerzburg, Germany)

Standardized instrument and position not mentioned

FEV₁, FEF_50%, ERV, FRC, TLC and FuncVC

After 6 months of treatment to reduce weight, there was an increase of 3.08% in FuncVC, 2.91% in FEV₁, 2.27% in TLC and 14.8% in ERV. WC had a (−) correlation with ERV. Changes in BMI score correlated with ERV

Weight reduction in children with morbid obesity may improve lung function, especially for ERV and airflow limitation

Alghadir et al. [40] (2012) – Saudi Arabia

To investigate the relationship between severity of obesity and parameters of lung function, comparing lung function in Saudi men with overweight and obesity with individuals with normal weight, and to compare the value found with the reference values for Caucasian individuals

Not mentioned (an interview and questionnaire about the medical history of lung infection were conducted, but did not mention this factor as exclusion criterion)

Cross-sectional

60 male individuals aged 6 to 13 years (20 in each group: with obesity, with overweight and with normal weight)

Spirometry (Pony FX - COSMED, Italy

Spirometry: ATS – sitting

FEV₁, FVC, FEV₁/FVC

The more fat a child has, the more compromised the lung function will be. Saudi children had lower value than predicted for height and age. In the group of individuals with obesity and overweight, there was a lower (predicted) value for FVC and FEV₁ and higher for FEV₁/FVC. Lung function of children with obesity was lower than that of the other groups, and the difference between the % of the measured value and the % of the predicted showed higher value in obesity for FVC and FEV₁ than in HC or individuals with overweight

Lung function of male Saudi Arabians with obesity or overweight was lower than that of children of the same age range in the HC group. The difference in relation to the predicted for their ages may indicate restriction in thoracic expansion and affect exercise capacity

Paralikar et al. [41] (2012) - India

To evaluate lung function in adolescents with obesity in the city of Baroda, Gujarat

Yes (cough)

Cross-sectional

60 male individuals aged 12 to 17 years (30 – with obesity and 30 – HC)

Spirometry (MEDI: SPIRO - Maestros Mediline Systems Ltd., Navi Mumbai, India)

Spirometry: ATS and ERS - sitting

FEV₁, FVC, FEV₁/FVC, PEF, FEF_25–75%, MVV

The mean % of predicted FEV₁ was lower in the group of individuals affected by obesity, as well as the mean absolute value and % of predicted FEV₁/FVC and MVV values. However, no individuals had OVD. Weight, BMI and WC had a (−) correlation with FEV₁/FVC, MVV and FEF_25–75%, and WHR with MVV and FEF_25–75%

Lung function among individuals with obesity was lower than that of the HC, being obesity a health risk in the evaluated age group. Despite the difference between groups, no individual had OVD or RDV. Longitudinal studies are needed to understand the relationship between increased body weight and lung function

Supriyatno et al. [42] (2010) - Indonesia

To determine the prevalence of abnormalities in lung function among Indonesian male adolescents and young people with obesity

Yes (children with exacerbated asthma)

Cross-sectional

110 children with obesity aged 10 to 12 years

Spirometry (PS7 Spirometer)

Spirometry: Polgar, 1971 - position not mentioned

FVC, FEV₁, FEV₁/FVC, FEF_25%, FEF_50%

In the sample, there was history of 29.1% asthma, 41.8% allergic rhinitis, 58.2% abnormality in lung function (30% MVD (obstructive and restrictive), 25.5% RVD and 2.7% OVD]

Abnormalities in lung function occur in obesity in early adolescence, with the most frequent change being MVD. There was no correlation between BMI and lung function. Studies are needed to assess the association of the degree of obesity and abnormalities in lung function with more accurate measures to assess body fat and with HC