Physical Activity and not Sedentary Time Influence on Metabolic Risk in Older Community-dwelling Women

Abstract

The risk of developing the metabolic syndrome increases by older age, where older women typically engage in less health-enhancing physical activity (PA) than men. Whether sedentary behaviors influence on metabolic risk and related components in older adults, and if so to what extent such relationships are independent of PA behavior, remain unclear. PURPOSE: To examine cross-sectional associations of objectively assessed PA and sedentary behaviors on metabolic syndrome components and clustered metabolic risk in a sample of older community-dwelling women. METHODS: Components of the metabolic syndrome including waist circumference (WC), systolic and diastolic blood pressures, fasting levels of plasma glucose, HDL-cholesterol and triglycerides were assessed in 120 community-dwelling older women (65-70 yrs). Total amount of PA (total counts per day), accumulated time spent in different intensities (sedentary, light (LPA), and moderate-to-vigorous PA (MVPA)), continuous bouts of sedentary time and breaks in sedentary time were assessed with accelerometers. Isotemporal substitution models were used to examine influence of PA and sedentary behavior on each component of the metabolic syndrome and on a clustered metabolic risk score. RESULTS:All associations between variables of sedentary behavior and metabolic risk were lost once variation in total accelerometer counts per day was adjusted for. Replacement of a 10-min time block of MVPA with either LPA or time in sedentary behaviors was related to an increase in WC and clustered metabolic risk score (zMS) (WC: β = 1.78 to 2.19 p < 0.01; zMS: β = 0.06 to 0.08, p < 0.05). CONCLUSIONS:Detrimental influence of a sedentary lifestyle on metabolic health is likely explained by variations in amounts of PA rather than sedentary time per se. Given our findings, increased amounts of PA with an emphasis on increased time in MVPA should be recommended in order to promote a favorable metabolic health profile in older women.