n South African Journal of Sports Medicine - Effect of body mass and physical activity volume and intensity on pedometry-measured activity energy expenditure in rural black South Africans in the Limpopo Province : original research article




. We developed a novel approach to investigate patterns of pedometry-measured total weekly activity energy expenditure (EE) in rural black South Africans in the Limpopo Province.

. We analysed 7-day pedometry data in 775 subjects (female: =508; male: =267). Variance components models for EE were used to estimate the variance explained by body mass (BM), total weekly steps (volume) and estimated intensity (kcal. kg-1.step-1). Univariate General Linear Models, adjusting for age, BM and physical activity (PA) volume, were used to determine if EE was primarily affected by volume or intensity.
. BM (13.1%), PA intensity (24.4%) and PA volume (56.9%) explained 94.4% of the variance in EE. Adjusted EEdid not differ between sexes (78 kcal.week-1, =0.2552). There were no significant differences across activity categories (sedentary to very active) for adjusted EE (62 - 287 kcal.week-1, p>0.1). Adjusted EE for 6 - 7 days of compliance (≥10 000 steps.day-1) differed significantly from 1 - 2 days of compliance (266 - 419 kcal.week-1, <0.04). Obese (body mass index ≥30 kg.m-2) and normal weight (body mass index 18.5 - 24.9 kg.m-2) women did not differ significantly across activity categories for EE (200 - 592 kcal.week-1, >0.30).
. We have highlighted an intensity effect for days of compliance and at very active ambulatory levels (≥12 500 steps. day-1). A volume effect appeared to dominate between sexes, across activity categories and weight-by-activity categories. It is important that statistical adjustments be made for body mass and PA volume when comparing EE across groups.


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