Influence of Cut-Points on Patterns of Accelerometry-Measured Free-Living Physical Activity in Rural and Urban Black South African Women

Background: We describe the effect of 2 different accelerometer cut-points on physical activity (PA) patterns in rural and urban black South African women. Methods: Hip-mounted uni-axial accelerometers were worn for 6 to 7 days by rural (n = 272) and urban (n = 16) participants. Twenty-hour (4 AM to 12 AM) PA counts (cts) and volumes (min.day(-1)) were extracted: sedentary (SED, <100 cts.min(-1)), light (100-759 cts.min-1), moderate-1 (MOD1, 760-1951 cts-min(-1)), moderate-2 to vigorous (MOD2VG, >= 1952 cts.min(-1)), and bouts >= 10 min for >= 760 cts.min(-4) (MOD1 VGbt) and >= 1952 cts.min(-1) (MOD2VGbt). Results: Valid data were obtained from 263 rural women and 16 urban women. Total counts and average counts were higher (+80,399 cts.day(-1), +98 cts.min(-1).day(-1)) (P < .01), SED lower (-61 min.day(-1), P = .0042), MOD 1 higher (+65 min-day(-1), P < .0001), and MOD I VGbt higher (+19 min-day(-1), P = .0179) in rural women compared with urban women. Estimated adherence (>= 30 min-day-1 for 5 days.wk(-1)) was 1.4-fold higher in rural women than urban women for MOD-1VGbt, but 3.3-fold higher in urban women than rural women for MOD2VGbt. Conclusions: Rural women accumulate greater amounts of PA. than urban women within a particular count band. Depending on which moderate PA cut-point was used to estimate PA public health adherence, rural women could be classified as less physically active than urban women.