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Abstract

Pedometers are useful tools for monitoring ambulatory physical activity (PA), typically measuring total steps/day. There is however little information concerning dose-response for health outcomes, in relation to intensity or duration of sustained steps. We aimed to examine this relationship, along with factors that mediate it, among employed adults. A convenience sample, recruited from work-site health risk screening (N=312, 37±9 yrs), wore a pedometer for at least 3 consecutive days. Steps were classified as ?aerobic? (≥100 steps/minute and ≥10 consecutive minutes) or ?non-aerobic? (<100 steps/minute and/ or <10 consecutive minutes). Health outcomes (blood pressure (BP), body mass Index (BMI), percentage body fat (%BF), waist circumference (WC), blood cholesterol and blood glucose) were associated with volume, intensity and duration of steps. Analyses of co-variance (ANCOVA), adjusting for age, gender and total steps/day were used to compare groups according to volume and intensity-based steps categories. A further analysis compared the mediation effect of body fat estimates (%BF, BMI and WC) independently on the association between steps and health outcomes. Our findings showed that the average steps/day accumulated were 6,574±3,541; total steps/day and average daily aerobic time were inversely associated with body fat estimates and systolic BP (p<0.05) in the expected direction. An ANCOVA showed a similar relationship between aerobic steps categories and health outcomes. Of the 3 body fat measures, %BF emerged as the strongest mediator of the relationship between steps and outcomes, whilst BMI showed the least mediation effect. Establishing appropriate pedometer-based recommendations that incorporate volume, intensity and duration of PA is, therefore an area of emerging importance.

Biography

Julian David Pillay has completed his Ph.D. at the age of 37 years from the University of Cape Town, South Africa. He is an academic in the Department of Basic Medical Sciences at the Durban University of Technology at present. He currently has published 6 papers in reputed journals, all of which relate to his master?s and Ph.D. work.