Compositional isotemporal substitution analysis of physical activity, sedentary behaviour and cardiometabolic biomarkers in US adults: A nationally representative study

ABSTRACT Substantial evidence links physical activity and sedentary behaviour (SB) with cardiovascular health. However, studies usually examine time‐use behaviours independently, rather than considering daily activities as a 24‐hour time‐use composition. This study aimed to use compositional data models to investigate how time reallocations from SB to moderate‐to‐vigorous physical activity (MVPA)/ light physical activity (LPA) were associated with changes in cardiometabolic biomarkers. Compositional isotemporal substitution analysis was conducted using data from a representative cross‐sectional sample of adults aged 20 years or older (n = 5213 full sample; n = 2221 fasting subsample) from the 2003–2004 and 2005–2006 cycles of the National Health and Nutrition Examination Survey. Overall as well as gender‐ and age‐specific estimates were obtained for reallocating time between the behaviours associated with cardiometabolic outcomes. Replacing SB with MVPA was associated with decreased levels of C‐reactive protein (CRP), white blood cells (WBCs), red blood cell distribution width (RDW), insulin, insulin resistance homeostasis model assessment (HOMA‐IR) and 2‐hour glucose, and increased high‐density lipoprotein cholesterol (HDL‐C), except for WBCs in older adults, insulin and HOMA‐IR in females and older adults, 2‐hour glucose in young and older adults, and HDL‐C in older adults. Substituting LPA for SB resulted in lower CRP in older adults, lower RDW in males and older adults, lower insulin in young and middle‐aged adults, lower HOMA‐IR in females and middle‐aged adults, and higher HDL‐C in males and young adults. Our findings provide new evidence for the potential benefits of LPA and MVPA in cardiovascular health and help make population‐specific recommendations for physical activity. Highlights Shorter sedentary behaviour (SB) time and longer active behaviours time are associated with a lower cardiovascular disease risk profile. Although replacing SB with MVPA has stronger positive health effects, LPA, as a simpler and more feasible activity, may has greater potential in promoting cardiovascular health. The expected changes in cardiometabolic biomarkers caused by time reallocations from SB to MVPA/LPA vary with gender and age, and physical activity guidelines with specific recommendations should be tailed to the subpopulations.