RESUMO
BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a complex, heterogeneous disease with multiple extrapulmonary manifestations, among which vitamin D deficiency and insufficiency are very common in COPD and are associated with the health status and clinical outcomes of COPD patients. OBJECTIVES: This paper aims to analyze the impact of leisure-time physical activity (LTPA) and daily sitting time (DST) and their interactions on serum vitamin D in patients with COPD. MATERIAL AND METHODS: Participants aged ≥40 years from the National Health and Nutrition Examination Survey (NHANES) in the USA from 2007 to 2012 who had undergone pulmonary function tests and vitamin D tests were selected as the study participants. Participants' LTPA and DST were assessed using the General Practice Assessment Questionnaire (GPAQ). Multivariate logistic regression analysis was used to analyze the relationship between serum vitamin D, LTPA, DSA and the combination of the 2 in patients with COPD, and the results were expressed as odds ratio (OR) and 95% confidence interval (95% CI). RESULTS: This study included 1,448 samples. The mean vitamin D concentration of the samples was (68.27 ±26.78) nmol/L; 360 participants (24.86%) had vitamin D deficiency and 539 participants (37.22%) had vitamin D insufficiency. Vitamin D and 25(OH)D3 expression levels differed across the 4 groups (150 min/week and DST > 8 h revealed the highest vitamin D expression levels, while LTPA 8 h showed the lowest. Vitamin D was weakly correlated with FEV1, FVC, BMI, age, and LTPA (p < 0.01), but not with DST. Body mass index (BMI) was weakly positively correlated with DST (r = 0.142, p < 0.01). CONCLUSIONS: Serum physical activity and DST independently affect vitamin D levels in COPD patients; therefore, increasing physical activity and minimizing DST may help improve vitamin D levels and prevent vitamin D deficiency.
