Physical Activity Behaviors of a Middle-Age South African Cohort as Determined by Integrated Hip and Thigh Accelerometry.

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Micklesfield, Lisa K 
Smith, Antonia 
Kufe, Clement N 
Mendham, Amy E 

PURPOSE: Descriptive studies of objectively measured physical activity behaviors in African populations are rare. We developed a method of combining hip and thigh accelerometery signals to quantify and describe physical behaviors in middle-age South African men and women. METHODS: We integrated signals from two triaxial accelerometers worn simultaneously during free-living, in a subsample of the Middle-age Soweto Cohort ( n = 794; mean (SD) age, 53.7 (6.3) yr). Acceleration time series from the accelerometers were combined and movement-related acceleration was derived using Euclidean Norm Minus One (in milligrams), to determine total movement volume (mean Euclidean Norm Minus One) and nonmovement time (<28 m g ), light-intensity physical activity (LPA; 28-85 m g ), and moderate- to vigorous-intensity physical activity (MVPA; >85 m g ); thigh pitch angle and a sleep diary were used to divide nonmovement time (in minutes per day) into sleep, awake sitting/lying, and standing. Sociodemographic factors were self-reported, and weight and height were measured. RESULTS: Mean (SD) wear time was 128 (48) h. Movement volume was 15.0 (6.5) m g for men and 12.2 (3.4) m g for women. Men spent more time in MVPA and sitting/lying, whereas women spent more time standing. Age was inversely associated with movement volume, MVPA, and LPA. When compared with their normal-weight counterparts, men who were overweight or obese spent less time in MVPA, whereas women who were overweight or obese spent less time in LPA and more time sitting/lying. Socioeconomic status was inversely associated with total movement volume, MVPA, and time spent sleeping, and positively associated with time spent sitting/lying, in both men and women. CONCLUSIONS: Integrating signals from hip and thigh accelerometers enables characterization of physical behaviors that can be applied in an African population.

Accelerometry, Exercise, Female, Humans, Male, Middle Aged, Obesity, Overweight, South Africa, Thigh
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Med Sci Sports Exerc
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Ovid Technologies (Wolters Kluwer Health)
Cambridge University Hospitals NHS Foundation Trust (CUH) (146281)
MRC (MC_UU_00006/4)
Medical Research Council (MC_UU_12015/3)
National Institute for Health and Care Research (IS-BRC-1215-20014)
The study was funded by the South African Medical Research Council (SAMRC) with funds received from the South African National Department of Health, the UKMRC (via the Newton Fund), and GSK Africa Non-Communicable Disease Open Lab (via a supporting Grant project no: ES/N013891/1). Supplementary funds were also received from the South African National Research Foundation (Grant no: UID:98561). KWe and AS were supported by the NIHR Cambridge Biomedical Research Centre (IS-BRC-1215-20014). TL, KWi, and SB were supported by the Medical Research Council (MC_UU_12015/3, MC_UU_00006/4). We are grateful to all MASC participants as well as DPHRU field staff.