Respiratory Effects of Obesity in Children: Longitudinal Consequences after 6 Years of Aging

Modified Project Summary/Abstract Section SUMMARY: Childhood obesity is one of the most common pediatric chronic diseases in the US. We have shown (HL136643) that over one year, children with obesity (CWO) can add four times as much fat weight as children without obesity (CWOO). However, it is unknown if this rate of increase in fat weight continues into adolescence, and whether respiratory function, exercise tolerance, or dyspnea on exertion (DOE) are progressively worsened by increasing obesity. Furthermore, there could be a sex difference in the effects of obesity, given the different growth characteristics for boys and girls. The overall objective of this proposal is to investigate the changes in body composition, lung function, exercise tolerance, and DOE after 6 years of aging in CWO and CWOO. In CWO, excess fat exerts an unfavorable burden on the respiratory system, particularly during exercise, potentially reducing exercise tolerance and leading to DOE. We have found that most of the respiratory effects in CWO are the result of low lung volume breathing, which exposes children to breathing limitations like expiratory flow limitation, gas exchange impairment, and greater perception of dyspnea. Our study approach will be to re-examine body composition, respiratory function, exercise tolerance, and DOE in CWO and CWOO who were originally studied as 8–12-year-olds (i.e., originally Tanner score ≤ 3; 90 participants; 26 CWOO & 64 CWO). Specific Aims: We will test the following hypotheses: Aim 1) CWO originally studied at 8-12 years old will demonstrate a greater increase in fat weight and lower respiratory function (i.e., altered pulmonary function & breathing mechanics at rest) than in CWOO originally studied at 8-12 years old; Aim 2) CWO originally studied at 8-12 years old will demonstrate lower exercise tolerance measured during graded cycle ergometry (peak V•O2 in ml/min/kg) than in CWOO originally studied at 8-12 years old, but not lower cardiorespiratory fitness (peak V•O2 in % of predicted based on ideal body wt.); and Aim 3) CWO originally studied at 8-12 years old will demonstrate greater DOE as evidenced by increased ratings of perceived breathlessness during constant load exercise cycling than in CWOO originally studied at 8-12 years old. These novel longitudinal results will have broad mechanistic relevance to our understanding of the effects of worsening obesity as children age.