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Descriptive Epidemiology of Ambulatory Activity in Rural, Black South Africans

COOK, IAN1; ALBERTS, MARIANNE2; BRITS, JOHANNA S.1; CHOMA, SOLOMON R.2; MKHONTO, STHEMBISO S.1

Medicine & Science in Sports & Exercise: July 2010 - Volume 42 - Issue 7 - p 1261-1268
doi: 10.1249/MSS.0b013e3181ca787c
BASIC SCIENCES: Contrasting Perspectives

Purpose: We investigated the distribution of objectively measured ambulation levels and the association of ambulation levels to adiposity levels in a convenience sample of adolescent and adult, rural black South Africans.

Methods: We analyzed 7-d pedometry data, collected over a period of nine consecutive days, in 789 subjects (women, n = 516; men, n = 273). Adiposity measures included body mass index (BMI) and waist circumference (WC). Obesity was defined as BMI ≥ 30 kg·m−2 or WC ≥ 102 cm for men and WC ≥ 88 cm for women.

Results: The average age- and BMI-adjusted 7-d ambulation level was 12,471 steps per day (95% confidence interval (CI) = 12,107-12,834). Ambulation levels differed between sexes (P = 0.0012), and weekday ambulation differed from weekend ambulation (P = 0.0277). Prevalences, age adjusted to the world population, for sedentarism (SED; <5000 steps per day), low active-somewhat active (5000-9999 steps per day), and active-very active (ACT; ≥10,000 steps per day) were 8.0%, 25.5%, and 66.6%, respectively. In contrast, published self-reported national prevalences for physical inactivity, insufficient physical activity, and physically active have been estimated to be 43%-49%, 20%-27%, and 25%-37%, respectively. After adjusting for sex and age, adiposity measures remained significantly associated with steps per day (BMI, r = −0.08; WC, r = −0.12; P < 0.03). Adjusting for sex, age, village, and season, SED increased the risk of obesity by more than twofold compared with ACT (P < 0.05). Achieving <10,000 steps per day compared with ACT was associated with an increased multivariate-adjusted obesity risk of 86%-89% (P < 0.001).

Conclusions: Ambulation levels were high for this rural African sample, and prevalences for SED and ACT differed from published self-reported estimates.

1Physical Activity Epidemiology Laboratory, University of Limpopo, Turfloop Campus, Polokwane, SOUTH AFRICA; and 2Department of Medical Sciences, University of Limpopo, Turfloop Campus, Polokwane, SOUTH AFRICA

Address for correspondence: Ian Cook, B.Sc. (Med.) Hons., Physical Activity Epidemiology Laboratory, University of Limpopo, Turfloop Campus, PO Box459, Fauna Park, 0787, Polokwane, South Africa; E-mail: ianc@ul.ac.za.

Submitted for publication June 2009.

Accepted for publication October 2009.

©2010The American College of Sports Medicine