Accelerometer-Determined Steps/Day and Metabolic Syndrome
ABSTRACT There is a lack of knowledge about the relationship between objectively measured physical activity and the odds of having metabolic syndrome (MetS) and cardiovascular (CVD) risk factors.
This study aims to investigate associations between accelerometer-determined steps/day and the odds of having MetS and its individual CVD risk factors in the U.S. population.
Adults in 2005-2006 NHANES with accelerometer-determined steps/day and measurements necessary to determine MetS by AHA/NHLBI were included (n=1446, 48.2% men, 33.5% with MetS, mean age=47.5 years, mean BMI=28.7 kg/m(2)). Logistic regression was used to estimate the odds of having MetS or abnormal CVD risk factors from incrementally higher levels of steps/day.
MetS prevalence decreased as steps/day increased (p<0.0001), with 55.7% of participants in the lowest categoric level of steps/day and 13.3% in the highest level having MetS. The odds of having MetS were 10% lower for each additional 1000 steps/day (OR=0.90, 95% CI=0.86, 0.93). The likelihood of having MetS was OR=0.28 (95% CI=0.18, 0.44) for active to highly active and 0.60 (0.43, 0.82) for low to somewhat-active compared to sedentary adults (p<0.0001). Adults who took more steps/day tended to have lower waist circumference, higher high-density lipoprotein (HDL) cholesterol level, and lower levels of triglycerides.
Adults who maintain an active lifestyle by accumulating more steps are likely to have a lower prevalence of MetS and its individual CVD risk factors. Although other concomitant lifestyle behaviors may influence this lower prevalence, the evidence presented here on steps/day and metabolic syndrome, and elsewhere on physical activity and other health and disease states, suggest that it is a fundamental component of daily living.
- SourceAvailable from: Dane Van Domelen[Show abstract] [Hide abstract]
ABSTRACT: Accelerometers are a valuable tool for measuring physical activity (PA) in epidemiological studies. However, considerable processing is needed to convert time-series accelerometer data into meaningful variables for statistical analysis. This article describes two recently developed R packages for processing accelerometer data. The package accelerometry contains functions for performing various data processing procedures, such as identifying periods of non-wear time and bouts of activity. The functions are flexible, computationally efficient, and compatible with uniaxial or triaxial data. The package nhanesaccel is specifically for processing data from the National Health and NutritionExamination Survey (NHANES), years 2003–2006. Its primary function generates measures of PA volume, intensity, frequency, and patterns according to user-specified data processing methods. This function can process the NHANES 2003–2006 dataset in under one minute, which is a drastic improvement over existing software. This article highlights important features of packages accelerometry and nhanesaccel and demonstrates typical usage for PA researchers.The R Journal 12/2014; 6(2):52-62. · 0.90 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Step counting (using pedometers or accelerometers) is widely accepted by researchers, practitioners, and the general public. Given the mounting evidence of the link between low steps/day and time spent in sedentary behaviours, how few steps/day some populations actually perform, and the growing interest in the potentially deleterious effects of excessive sedentary behaviours on health, an emerging question is "How many steps/day are too few?" This review examines the utility, appropriateness, and limitations of using a reoccurring candidate for a step-defined sedentary lifestyle index: <5000 steps/day. Adults taking <5000 steps/day are more likely to have a lower household income and be female, older, of African-American vs. European-American heritage, a current vs. never smoker, and (or) living with chronic disease and (or) disability. Little is known about how contextual factors (e.g., built environment) foster such low levels of step-defined physical activity. Unfavorable indicators of body composition and cardiometabolic risk have been consistently associated with taking <5000 steps/day. The acute transition (3-14 days) of healthy active young people from higher (>10 000) to lower (<5000 or as low as 1500) daily step counts induces reduced insulin sensitivity and glycemic control, increased adiposity, and other negative changes in health parameters. Although few alternative values have been considered, the continued use of <5000 steps/day as a step-defined sedentary lifestyle index for adults is appropriate for researchers and practitioners and for communicating with the general public. There is little evidence to advocate any specific value indicative of a step-defined sedentary lifestyle index in children and adolescents.Applied Physiology Nutrition and Metabolism 02/2013; 38(2):100-14. DOI:10.1139/apnm-2012-0235 · 2.23 Impact Factor
Conference Paper: Hypergraph partitioning with fixed vertices[Show abstract] [Hide abstract]
ABSTRACT: We empirically assess the implications of fixed terminals for hypergraph partitioning heuristics. Our experimental testbed incorporates a leading-edge multilevel hypergraph partitioner and IBM-internal circuits that have recently been released as part of the ISPD-98 Benchmark Suite. We find that the presence of fixed terminals can make a partitioning instance considerably easier (possibly to the point of being “trivial”): much less effort is needed to stably reach solution qualities that are near best-achievable. Toward development of partitioning heuristics specific to the fixed-terminals regime, we study the pass statistics of flat FM-based partitioning heuristics. Our data suggest that with more fixed terminals, the improvements in a pass are more likely to occur near the beginning of the pass. Restricting the length of passes-which degrades solution quality in the classic (free-hypergraph) context-is relatively safe for the fixed-terminals regime and considerably reduces run time of our FM-based heuristic implementations. We believe that the distinct nature of partitioning in the fixed-terminals regime has deep implications (i) for the design and use of partitioners in top-down placement, (ii) for the context in which VLSI hypergraph partitioning research is pursued, and (iii) for the development of new benchmark instances for the research communityDesign Automation Conference, 1999. Proceedings. 36th; 02/1999