JMIR Publications

ABSTRACT

Background:

Sedentary behavior has received much attention in the scientific community over the past decade. There is growing evidence that sedentary behavior is negatively associated with physical and mental health. However, an in-depth understanding of the social and environmental context of sedentary behavior is missing. Information such as how everyday sedentary behavior occurs throughout the day (e.g., number and length of sedentary bouts), where, when, and with whom it takes place, and what people are doing while being sedentary is useful to inform the development of interventions aimed at reducing sedentary time. However, examining everyday sedentary behavior requires specific methods.

Objective:

The purpose of this paper was (i) to introduce sedentary triggered Ecological Momentary Assessment (EMA) as a methodological advancement in the field of sedentary behavior research and (ii) to examine the accuracy of sedentary triggered EMA in three different studies in healthy adults. Moreover, we estimated the added value of sedentary triggered EMA compared to a simulation of a random-trigger design.

Methods:

Sedentary triggered EMA comprises continuous assessment of sedentary behavior via accelerometers and repeated contextual assessments via electronic diaries (i.e., an application on a smartphone). More specifically, the accelerometer analyzes and transfers data regarding body position (sitting/lying or upright) via Bluetooth Low Energy (BLE) to a smartphone in real-time and triggers the deployment of questionnaires. Each time a participant spends a specified time (e.g., 20 min) in a sedentary position, the e-diary triggers contextual assessments. To test the accuracy of this method, we calculated a percentage score for all triggered prompts in relation to the total number of bouts that could trigger a prompt.

Results:

Based on the accelerometer recordings, 29.3% of all sedentary bouts were classified as moderate-to-long (20-40 min) and long bouts (≥ 41 min). On average, the accuracy by participant was 82.77% (SD: ± 21.01%), ranging from 71 to 88.22% on the study level. Compared to simulations of random prompts (every 120 min), the accuracy of the sedentary triggered EMA was up to 47.9% higher. Nearly 40% of all prolonged sedentary bouts (≥ 20 min) occurred during work, and in 57% of all bouts, the participants were not alone.

Conclusions:

Sedentary triggered EMA is an accurate method for collecting contextual information on sedentary behavior in daily life. Given the growing interest in sedentary behavior research, this sophisticated approach offers a real advancement as it can be used to collect social and environmental contextual information or to unravel dynamic associations. Furthermore, it can be modified to develop sedentary triggered mHealth interventions.