Epoch length and the physical activity bout analysis: An accelerometry research issue

Abstract

BackgroundThe purpose of the present investigation was to compare the bouts of daily physical activity (PA) determined by three different accelerometer epoch lengths under free-living conditions.MethodsOne hundred thirty-four adults (50 ± 7 years) wore an accelerometer (Lifecorder) for 7 consecutive days under free-living conditions in order to determine the time spent in physical activity of light intensity (LPA), moderate intensity (MPA), vigorous intensity (VPA), moderate to vigorous intensity (MVPA), and the total physical activity (TPA; sum of LPA, MPA and VPA). Additionally, all PA was divided according to the bout durations (sporadic, >3 min, >5 min, and > 10 min). These indices of PA were analyzed using three different epoch lengths (4 sec, 20 sec and 60 sec) derived from the accelerometer.ResultsThe LPA significantly increased in association with increases in the epoch length (48.7 ± 15.9 to 178.7 ± 62.6 min/day, p < 0.05). The amount of sporadic VPA determined by the shortest epoch length (2.9 ± 5.2 min/day) was significantly longer than the two remaining epoch lengths (1.1 ± 2.4 to 0.9 ± 2.5 min/day, p < 0.05). The times of the MVPA bouts lasting longer than 3 minutes determined using the 4-second epoch length (2.6 ± 5.4 to 7.7 ± 10.0 min/day) were significantly shorter than those determined using the other two settings (6.5 ± 10.5 to 13.8 ± 13.8 min/day, p < 0.05). The frequencies of the MVPA bouts lasting longer than 10 minutes determined using the 4-second epoch length (0.2 ± 0.3 bouts/day) were significantly lower than those determined using the other two settings (0.3 ± 0.4 bouts/day, p < 0.05).ConclusionThe epoch length setting of the accelerometer affects the estimation of the PA bouts under free-living conditions in middle-aged to older adults.

Movement behaviour in adults with haemophilia compared to healthy adults

“…The sample sizes of patients with severe haemophilia and healthy adults were sufficient to identify differences between those groups. Thirdly, previous studies show that different definitions of an active bout and differences in accelerometer settings (eg the interval at which postures and activities are determined) yield different results when evaluating the number and length of active bouts . Currently, there is no consensus on an optimal definition or settings to determine active bouts.…”

“…Thirdly, previous studies show that different definitions of an active bout and differences in accelerometer settings (eg the interval at which postures and activities are determined) yield different results when evaluating the number and length of active bouts. 26 Currently, there is no consensus on an optimal definition or settings to determine active bouts. When interpreting the data, the definition and accelerometer settings should therefore be taken into account.…”

The Scientific Foundation for the Physical Activity Guidelines for Americans, 2nd Edition

“…Recent research using device-measured physical activity and assessing a variety of cardiometabolic health indicators indicates that bouts of MVPA of any length (ie, time duration) contribute to the health benefits associated with the accumulated total volume of physical activity. [32][33][34][35][36][37][38][39][40][41][42][43][44][45][46] Of 40 comparisons within 14 studies, 78% (31 comparisons) indicated that bouts <10 minutes long were as good or better than bouts ≥10 minutes. 1 An additional 10% (4 comparisons) reported that bouts <10 minutes long were associated with risk reduction but did not make a direct comparison with bouts ≥10 minutes.…”

Interruption in physical activity bout analysis: an accelerometry research issue

“…Most of subjects are same as the previous publications [6], the details are not shown in the present paper. The characteristics of the participants are shown in Table 1.…”