10-year Changes In Accelerometer-determined Physical Activity And Sedentary Time During Midlife

Abstract

PURPOSE: Describe the 10-year race/sex specific changes in accelerometer-determined physical activity (PA) and sedentary time in a midlife cohort. METHODS: Data are from 881 Coronary Artery Risk Development in Young Adults (CARDIA) participants aged 18 to 30 years at baseline (1985-86) who wore the accelerometer and had valid wear (≥4 of 7 days, ≥10 hours per day) at the Year 20 (2005-06; ages 38-50) and Year 30 (2015-16; ages 48-60) exams. At Year 20, accelerometer measures were first collected using the ActiGraph 7164; at Year 30 the ActiGraph wGT3X-BT model was used. A calibration factor (counts divided by 1.088, based on a subset who simultaneously wore both devices at Year 30) was applied to Year 30 data to account for differences in models. All 10-year change estimates are expressed as median (25th, 75th percentiles). Wilcoxon Rank Sum tests were used to examine 10-year changes overall and within the four race/sex groups. RESULTS: Over 10 years, participants experienced significant reductions in average accelerometer counts [-46.7 (-122.7, 31.1 ct·min·d-1; p<0.001]. This reduction was shown within each race/sex group, with the greatest decline observed in black men (all p<0.001). Sedentary time significantly increased overall (32.9 min[BULLET OPERATOR]d-1), with the largest increases shown in black women (56.9 min[BULLET OPERATOR]d-1) followed by black men (50.2 min[BULLET OPERATOR]d-1), white women (28.9 min[BULLET OPERATOR]d-1) and men (19.0 min[BULLET OPERATOR]d-1); all p<0.001. Light intensity PA decreased (-29.2 min[BULLET OPERATOR]d-1), with black men having the greatest reductions (-38.3 min[BULLET OPERATOR]d-1), followed by white (-35.3 min[BULLET OPERATOR]d-1) and black (-26.6 min[BULLET OPERATOR]d-1) women, then white men (-25.6 min[BULLET OPERATOR]d-1); all p<0.001. Moderate to vigorous intensity PA (MVPA) also declined (-5.5 min[BULLET OPERATOR]d-1) with the largest reductions shown in black men (-7.3 min[BULLET OPERATOR]d-1), then white men (-6.9 min[BULLET OPERATOR]d-1), and white (-4.9 min[BULLET OPERATOR]d-1) and black (-4.3 min[BULLET OPERATOR]d-1) women; all p<0.001. Of note, black women had the lowest accumulated MVPA at Year 20. Finally, median time spent in MVPA bouts lasting ≥8 of 10 consecutive minutes slightly increased in white men and women (2.3 and 0.60 min[BULLET OPERATOR]d-1, respectively; both p<0.01), which was not shown in black participants. CONCLUSIONS: We found a decline in overall PA during the midlife transition. This reduction was largely attributable to increases in sedentary time and reductions in light intensity PA.