Obesity Indices for Predicting Functional Fitness in Children and Adolescents With Obesity

Abstract

Objectives: We aimed to determine the obesity indices that affect 6-min walk test (6-MWT) distance in children and adolescents with obesity and to compare the 6-MWT distance of obese subjects with that of normal-weight subjects.Methods: Obese children and adolescents aged 8–15 years and normal-weight age- and gender-matched controls were enrolled. All participants performed the 6-MWT; respiratory muscle strength (RMS), including maximal inspiratory pressure and maximal expiratory pressure; and spirometry. Data between groups were compared. In the obesity group, correlation between obesity indices and pulmonary function testing (6-MWT, RMS, and spirometry) was analyzed.Results: The study included 37 obese and 31 normal-weight participants. The following parameters were all significantly lower in the obesity group than in the normal-weight group: 6-MWT distance (472.1 ± 66.2 vs. 513.7 ± 72.9 m; p = 0.02), forced expiratory volume in one second/forced vital capacity (FEV1/FVC) (85.3 ± 6.7 vs. 90.8 ± 4.5%; p < 0.001), forced expiratory flow rate within 25–75% of vital capacity (FEF25−75%) (89.8 ± 23.1 vs. 100.4 ± 17.3 %predicted; p = 0.04), and peak expiratory flow (PEF) (81.2 ± 15 vs. 92.5 ± 19.6 %predicted; p = 0.01). The obesity indices that significantly correlated with 6-MWT distance in obese children and adolescents were waist circumference-to-height ratio (WC/Ht) (r = −0.51; p = 0.001), waist circumference (r = −0.39; p = 0.002), body mass index (BMI) (r = −0.36; p = 0.03), and chest circumference (r = −0.35; p = 0.04). WC/Ht was the only independent predictor of 6-MWT distance by multiple linear regression.Conclusions: Children and adolescents with obesity had a significantly shorter 6-MWT distance compared with normal-weight subjects. WC/Ht was the only independent predictor of 6-MWT distance in the obesity group.

Effect of Threshold Inspiratory Muscle Training on Functional Fitness and Respiratory Muscle Strength Compared to Incentive Spirometry in Children and Adolescents With Obesity: A Randomized Controlled Trial

“…No significant difference among the IMT, IS, and control groups was found for any variable relative to change from baseline to after 8 weeks of respiratory muscle training (Table 2). Several studies reported reduced RMS and functional fitness in children and adolescents with obesity (5)(6)(7)(8)(9). This is attributed to excessive fat deposition on the chest wall and abdomen, which contributes to dysfunction of the inspiratory muscles (especially the diaphragm), reduced chest wall compliance, reduced lung volume, and impaired lung mechanics that collectively lead to decreased functional fitness (8,39).…”

“…Several studies reported reduced RMS and functional fitness in children and adolescents with obesity ( 5 – 9 ). This is attributed to excessive fat deposition on the chest wall and abdomen, which contributes to dysfunction of the inspiratory muscles (especially the diaphragm), reduced chest wall compliance, reduced lung volume, and impaired lung mechanics that collectively lead to decreased functional fitness ( 8 , 39 ).…”

“…The effects of obesity on the respiratory system include altered pulmonary function and exercise intolerance, and comorbid obesity can also worsen both asthma and obstructive sleep apnea (4). Several studies reported reduced functional fitness and reduced respiratory muscle strength (RMS) in children and adolescents with obesity (5)(6)(7)(8)(9), and these deficiencies may contribute to dyspnea on exertion. The principle pillar of treatment for obesity is weight reduction.…”