“Sedentary behavior” is defined as sitting or lying with low energy expenditure (SBRN, 2012). In isolation, energy expenditure provides no reliable information about body posture (e.g. sitting vs. standing), an essential component of assessing sedentary behavior (Holtermann, et al., 2017). Conversley, assessing body posture alone cannot provide insights into energy expenditure, e.g. machine sewing while sitting, crane operators, lifting weights in the gym (Holtermann, et al., 2017). To accurately determine sedentary behaviour requires the assessment of both body posture and energy expenditure.

Reliable methods to measure and assess "sedentary behavior"

• Case 1: Known environment – e.g. no possibility to stand and all low physical activity ≙ sitting. In this case attaching a sensor at the hip (Move 3) provides only a rough estimation of sedentary behavior.
• Case 2: Differentiating between sitting/lying & standing. By attaching a sensor (Move 3) to the thigh, the different angles of the axis allow differentiation between sitting/lying and standing. But it is not possible to differentiate between sitting and lying (Byrom, Stratton, McCarthy, & Muelhausen, 2016).
• Case 3: Assessing changes in time distribution of sedentary behavior – requiring the precise distribution of sedentary behavior and physical activity intensity. This case requires the assessment of both body posture and energy expenditure. This is possible by attaching one sensor (Move 3) at the thigh (sitting/lying vs. standing) and one (Move 3) at the upper body/hip (standing/sitting vs. lying). Additionally, the sensor at the upper body/hip provides the data necessary to estimate energy expenditure (Holtermann, et al., 2017)
• Case 4: Assessing changes in time distribution of sedentary behavior with a static load. In this case the use of an ecg-sensor provides additional data to assess energy expenditure. Initially the ecg-sensor requires calibration to estimate energy expenditure with additional load. Attaching one sensor (Move 3) at the thigh (sitting/lying vs. standing) and one physical activity and ecg-sensor (EcgMove 3) at the upper body (standing/sitting vs. lying) provides acceleration data from two positions, and the additional ecg-signal allows improved energy expenditure estimations during static work, due to the linear relationship between cardiorespiratory stress and energy expenditure (Holtermann, et al., 2017).
• Case 5: If an intervention is necessary, or if the research requires additional subjective parameters, we offer the possibility to trigger a questionnaire with our experience sampling platform movisensXS via our SensorTrigger. After the application detects 30 minutes (customizable by the researcher) of sedentary behaviour (<1.5MET) from the sensor, the trigger displays a form on a smartphone app prompting the participant to answer a questionnaire. This offers the possibility to obtain detailed feedback and insights into the daily routine of the study participant.