Ambulatory Tasks and Journeys: A Framework for Free-Living Behaviour

Area of Science:

• Physical activity research
• Behavioral science
• Biomedical engineering

Background:

• Standard activity monitors do not differentiate between types of upright behavior.
• A new Ambulatory Behaviour Framework distinguishes between Ambulatory Tasks (standing/short stepping) and Ambulatory Journeys (longer stepping).

Purpose of the Study:

• To introduce and validate a novel framework for classifying upright behaviors using accelerometer data.
• To investigate the relationship between different types of upright behaviors and sitting time.

Main Methods:

• Analysis of thigh-worn accelerometer data from 3545 participants in the 1970 British Cohort Study.
• Development of event-based algorithms to classify upright events into Ambulatory Tasks or Ambulatory Journeys.
• Linear models used to assess associations with sitting time, sex, and BMI.

Main Results:

• Ambulatory Tasks comprised 90.6% of upright time, while Ambulatory Journeys accounted for 9.4%.
• Each hour of Ambulatory Tasks reduced sitting time by 0.61 hours; each hour of Ambulatory Journeys reduced sitting time by only 0.04 hours.
• Women spent more time in Ambulatory Tasks and less time sitting than men; both behaviors decreased with higher BMI.

Conclusions:

• Ambulatory Tasks are effective in displacing sitting time, unlike Ambulatory Journeys.
• Interventions aimed at reducing sedentary behavior should focus on promoting frequent, short bouts of activity.
• The proposed framework provides interpretable, sensor-agnostic metrics for behavior change and mobility research.