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.
Highlights
Obesity is a major global public health problem among both children and adults, and its prevalence continues to increase [1,2,3]
A comparison of 6-minute walk test (6-MWT) distance, spirometry, and respiratory muscle strength (RMS) between the obese and normal-weight groups revealed that the obesity group had a significantly shorter 6-MWT distance (472.1 ± 66.2 vs. 513.7 ± 72.9 m; p = 0.02), lower forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) (85.3 ± 6.7 vs. 90.8 ± 4.5%; p < 0.001), lower FEF25−75% (89.8 ± 23.1 vs. 100.4 ± 17.3 %predicted; p = 0.04), and lower peak expiratory flow (PEF) (81.2 ± 15.0 vs. 92.5 ± 19.6 %predicted; p = 0.01) compared to the normal-weight group (Table 2)
Our study showed that the obesity group had a significantly shorter 6MWT distance compared to the normal-weight group, which is consistent with previous studies [6, 8, 9]
Summary
Obesity is a major global public health problem among both children and adults, and its prevalence continues to increase [1,2,3]. Most previous studies of pulmonary function testing (PFT) in children and adolescents with obesity used spirometry or lung volume testing, neither of which is measured during physical activity. The 6-minute walk test (6-MWT) is a PFT that measures how many meters a person can walk in 6 min This test is simple and inexpensive, and it is both a cause of fatigue and a method for helping to measure it in obese individuals. It is helpful for assessing functional capacity and an individual’s ability to perform activities of daily living [4, 5]. Most studies of the 6-MWT were conducted in adults, with only a few conducted in obese children and adolescents [6,7,8,9,10,11]
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