Longitudinal Associations between 24-H Movement Behaviors and Cardiometabolic Biomarkers: A Natural Experiment over Retirement.

INTRODUCTION: Physical activity, sedentary behavior and sleep, that is, 24-h movement behaviors, often change in the transition from work to retirement, which may affect cardiometabolic health. This study investigates the longitudinal associations between changes in 24-h movement behaviors and cardiometabolic biomarkers during the retirement transition.

METHODS: Retiring public sector workers (n = 212, mean age 63.5 years, SD 1.1) from the Finnish Retirement and Aging study used a thigh-worn Axivity accelerometer and filled out a diary to obtain data on daily time spent in sedentary behavior (SED), light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA) and sleep before and after retirement (one year in-between). Cardiometabolic biomarkers, including LDL-cholesterol, HDL-cholesterol, total:HDL-cholesterol ratio, triglycerides, C-reactive protein (CRP), fasting glucose and insulin, were measured. Associations between changes in 24-h movement behaviors and cardiometabolic biomarkers were analyzed using compositional robust regression and isotemporal substitution analysis.

RESULTS: Increasing LPA in relation to remaining behaviors was associated with an increase in HDL-cholesterol and decrease in total:HDL-cholesterol ratio (p < 0.05 for both). For instance, reallocation of 30 min from sleep/SED to LPA was associated with an increase in HDL-cholesterol by 0.02 mmol/l. Moreover, increasing MVPA in relation to remaining behaviors was associated with a decrease in triglycerides (p = 0.02). Reallocation of 30 min from SED/sleep to MVPA was associated with 0.07 - 0.08 mmol/l decrease in triglycerides. Findings related to LDL-cholesterol, CRP, fasting glucose and insulin were less conclusive.

CONCLUSIONS: During the transition from work to retirement, increasing physical activity at the expense of passive behaviors was associated with a better lipid profile. Our findings suggest that life transitions like retirement could be utilized more as an optimal time window for promoting physical activity and health.