Patterns of Accelerometer-Assessed Sedentary Behavior in Older Women

Purpose To examine characteristics of accelerometer-assessed sedentary behavior among older women.

Methods An ancillary study to the Women’s Health Study is collecting 7 days of accelerometer-assessed (Actigraph GT3X+) physical activity and sedentary behavior data in ~15,000 women. This analysis includes data from the first 5,032 (mean age, 70.1 yr) women with ≥4 days of ≥10 hours of wear per day (93% of sample). The cutpoint of <100 counts per min (cpm) was used to define sedentary behavior time. We then investigated bouts of sedentary behavior, defined as a period of at least 1, 5,10, 20, or 30 consecutive minutes where cpm was <100 cpm. We calculated the median number of sedentary bouts per day that were at least 1, 5, 10, 20, or 30 minutes’ duration, as well as the median percent of total sedentary bouts per day in these bout duration categories.

Results Women wore the accelerometer for a mean of 14.3 (SE = + 0.02) hours. The median duration of wear time spent in sedentary behavior was 67.5% (10th, 90th percentile: 56.1%, 77.9%), which was equivalent to 9.6 hours per day. The median number of sedentary bouts per day was 79.3. A median of 27.9 sedentary bouts per number of sedentary bouts per day was 79.3. A median of 27.9 sedentary bouts per day were of at least 5 minutes, representing 35.6% of total sedentary bouts per day. A median number of 15.2 of sedentary bouts per day were at least 10 minutes (19.4%); 6.7 at least 20 minutes (8.5%); and 3.6 at least 30 minutes (4.6%) (Table).

Conclusions Based on accelerometer measures, these older women spent about two-thirds of waking time in sedentary behavior. Most of this sedentary time occurred in bout durations of < 10 min.

Supported in part by NIH CA154647