How bout variables are derived by ActiPASS - Ergo-Tools/ActiPASS GitHub Wiki

How physical activity (PA), sedentary behaviour (SB) or intensity-class (SED, LPA, MVPA, VPA etc.) bouts are derived by ActiPASS

A "bout" refers to a period of time during which a specific behaviour is performed. Bouts can either be defined based on specific behaviours like bouts of sitting, standing, walking etc. or based on periods of different intensity classes such as bouts of sedentary time (SED), low intensity physical behaviour (LPA), moderate to vigorous physical behaviour (MVPA) etc.

ActiPASS has an epoch length of 1 second. This means that ActiPASS produces a behaviour class every second (however, the effective epoch-length for activities/behaviours varies between around 2 seconds up to 20 seconds depending on the activity/behaviour). A consequence of this high time resolution is that within a specific behaviour (as perceived by us: for example, a 20-minutes walking-period) many intermittent short breaks (for example standing or running) can exist in ActiPASS output. Still, we perceive the walking period as a continuous bout.

In the default ProPASS mode of ActiPASS, a bout is defined by:

a) the bout length (bouts are defined which are longer than 1, 2, 3, 4, 5, 10 and 30 minutes)

b) a maximum duration (default 20 seconds) of other behaviours which is needed to break the bout

Thus, a bout of a particular behaviour or intensity-class in ActiPASS is derived by considering a minimum continuous duration allowing small intermittent breaks.

Example:

image

  • The 40s and 32s non-walk periods in the beginning and end define the start and stop of the bout because they are longer than 20s, the other non-walk periods will not break the bout as they are shorter than 20s.
  • This episode will be included in 1,2 and 3 min bouts as 227 seconds is less than 4 minutes.

To be aware of:

  1. Any no-walk activities will break the walking bout. This means that not only activities with lower intensity than walking but also activities with higher intensities than walking such as running will break a walking bout.
  2. In extreme cases there could be a large number of intermittent breaks that occurs within a bout period. Then the actual time of the activity will be considerably smaller than that particular bout duration. Then we do not perceive that time period as a bout.

An example: We want to find walking bouts that are larger than 5 minutes. Say that one such particular bout is 309 seconds long but actual walking time within that bout is only 200 seconds (because the person has been walking and stopping repeatedly) (see example below) This situation is perhaps not generally perceived as a walking bout larger than 5 minutes.

image

One solution to this is to add an additional criterion called a bout-threshold. This is available as an option in the advanced mode in ActiPASS but not in the default ProPASS mode.

A bout-threshold is the actual time of a particular behaviour/intensity-class as a percentage of the length of the particular bout concerned. In the example above the 309 seconds walking bout contains 200 seconds of actual walking, then bout-threshold is 200/309=64%. If ActiPASS bout threshold is used (and set to default 80%) then above 309 seconds bout will be ignored.