Associations of low- and high-intensity light activity with cardiometabolic biomarkers

PURPOSE: Light-intensity physical activity (LIPA) accounts for much of adults' waking hours (≈40%) and substantially contributes to overall daily energy expenditure. Encompassing activity behaviours of low intensity (standing with little movement) through to those with a higher intensity (slow walking), LIPA is ubiquitous, yet little is known about how associations with health may vary depending on its intensity. We examined the associations of objectively assessed LIPA, categorized as either low- or high- LIPA, and MVPA, with cardiometabolic risk biomarkers. METHODS: Cardiometabolic biomarkers were measured in 4614 US adults (47±17 yrs) who participated in the 2003-04 and 2005-06 National Health and Nutrition Examination Survey (NHANES) cycles. Multiple linear regression analyses examined associations of three accelerometer-derived physical activity (SD increment/day) intensity categories (low-LIPA [LLPA: 100-761 counts·min]; high-LIPA [HLPA: 762-1951 counts·min]; moderate [MPA: 1952-5724 counts·min] and, vigorous [VPA: ≥5725 counts·min]) with cardiometabolic biomarkers, adjusting for potential socio-demographic, behavioral, and medical confounders. RESULTS: All intensities of physical activity were beneficially associated with waist circumference, C-reactive protein, triglycerides, fasting insulin, β-cell function and insulin sensitivity (P<0.05); only some activity intensities showed significant associations with systolic blood pressure (LLPA), body mass index, high-density lipoprotein cholesterol, fasting and 2 hour plasma glucose (HLPA, MPA, VPA). Generally, size of effect increased with PA intensity. Overall, further adjustment for waist circumference attenuated associations with MPA and VPA to a greater extent than with LLPA and HLPA. CONCLUSIONS: These cross-sectional findings provide novel evidence for the potential benefits of increasing both LLPA and HLPA; they further reinforce the established importance of MVPA - the mainstay of public health recommendations.