The purpose of the study is to re-examine body composition, respiratory function, exercise tolerance, and dyspnea on exertion (DOE) in children with obesity (CWO) and children without obesity (CWOO) who were originally studied as 8-12-year-olds between 2016-2023 (i.e., originally Tanner score ≤ 3; 90 participants; 26 CWOO & 64 CWO).

The prevalence of childhood obesity increases with age (20.7% aged 6-11 & 22.2% aged 12-19; NHANES 2017-2020). CWO, compared with CWOO, are more likely to have chronic health conditions.

Results from the investigator's prior grant (HL136643) show that over one year, CWO can add four times as much fat weight as CWOO. However, it is unknown if this rate of increase in fat weight continues into adolescence and early adulthood, and whether respiratory function, exercise tolerance, or 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 investigator's long-term objective is to investigate the effects of 6 years of aging on body composition, respiratory function, exercise tolerance, and DOE in CWO and CWOO.

Specific Aims: The investigators will test the following hypotheses in CWO and CWOO after 6 years of aging:

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 (as evidenced by peak V • O2 in ml/min/kg, i.e., physical fitness) than in CWOO originally studied at 8-12 years old, but not lower cardiorespiratory fitness (as evidenced by peak V • O2 in % of predicted based on ideal body wt., i.e. cardiorespiratory fitness);

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; and

Inclusion Criteria:

The participants originally studied as 8-12-year-olds between 2016-2023 as part of the investigator's R01 HL136643.

Exclusion Criteria:

1. Children not able to follow directions, adequately perform procedures (e.g., pulmonary function tests), or keep appointments (e.g., no shows for testing).
2. If a child developed an abnormal ECG, showed other signs of clinical exercise intolerance, or signs of cardiovascular/lung disease during the exercise test, testing was terminated, and the child was referred to their personal physician for further evaluation.
3. Women who are pregnant or could possibly be pregnant (i.e. not using approved birth control measures and sexually active) will be excluded because of changes in body size during pregnancy and because unforeseeable risks to the fetus.
4. Presence of significant disease defined as a disease which in the opinion of the investigator may put the subject at risk because of participation in the study or a disease that may influence the results of the study or the subject's ability to participate in the study.
5. Patients who are non-English speaking will be excluded from the study because the tests performed are very effort dependent, detailed and require technical communication between the staff and the patient. The investigators feel that a translator would not be able to translate the technical terms fast enough to instruct the patient in the testing.

The participants originally studied as 8-12-year-olds between 2016-2023 as part of the investigator's R01 HL136643.