Visceral adiposity and respiratory outcomes in children and adults: a systematic review.

BACKGROUND: This review aimed to examine the associations of visceral adipose tissue (VAT) with pulmonary function and asthma in children and adults, and chronic obstructive pulmonary disease (COPD) in adults. METHODS: Five databases were searched up to February 12, 2021, to identify articles that described associations of VAT with pulmonary function, asthma, and COPD. Information on participant characteristics, study design and assessment, and key findings were retrieved. RESULTS: A total of 43 studies were considered eligible, of which most studies were cross-sectional and in adults. The quality of included studies was generally moderate. In adults, strong evidence was found that a higher abdominal VAT was associated with asthma, and a higher intrathoracic VAT was associated with lower forced expiratory volume in the first second and forced vital capacity. Inconclusive results were found although a substantial number of studies suggested inverse association of abdominal VAT with pulmonary function. There is a limited number of studies addressing the relationship between VAT and COPD. CONCLUSION: The literature to date provides strong evidence in adults for the associations of higher abdominal VAT with asthma, and higher intrathoracic VAT with lower lung function parameters. Future high-quality studies are warranted that adjust sufficiently for key confounding factors such as fat distribution.

Associations of physical condition with lung function and asthma in adolescents from the general population.

BACKGROUND: The relation of physical condition with respiratory outcomes in adolescents is unclear. We examined the hypothesis that adolescents with a lower physical condition represented by a lower cardiorespiratory fitness and physical activity, and a higher screen time have a lower lung function and higher risk of asthma. METHODS: In a population-based prospective cohort study on 4854 children aged 13 years, we assessed cardiorespiratory fitness by using the peak work rate measured by the steep ramp test. Information on physical activity and screen time was obtained by self-reported questionnaires. Lung function was measured by spirometry and current asthma was assessed by a parental-reported questionnaire. RESULTS: Taking sociodemographic, lifestyle, and growth-related confounders and multiple hypothesis testing into account, a 1 SD lower cardiorespiratory fitness was associated with a lower FEV1 , FVC, and FEF75 (Z-score difference (95% CI): -0.31 (-0.35, -0.28), -0.30 (-0.33, -0.26), -0.13 (-0.17, -0.10), respectively), and a higher risk of asthma (Odds Ratio (95% CI) 1.25 (1.06, 1.46)). A 1 SD higher screen time was associated with a lower FVC (Z-score difference (95% CI): -0.06 (-0.10, -0.03)). Physical activity and screen time were not related to asthma. Results did not materially change after additional adjustment for respiratory outcomes at an earlier age. CONCLUSION: Adolescents with a lower cardiorespiratory fitness had a lower lung function and a higher risk of asthma. Those with a higher screen time had a lower FVC. Further studies are needed to explore the effect of improvements in physical condition on long-term respiratory outcomes.