Validation of a smart chair and corresponding smartphone app as an objective measure of desk-based sitting.

OBJECTIVES: This study evaluated the validity of a smart chair and corresponding smartphone app (chair&app) to measure sitting time and sitting interruptions against camera-derived observation and activPAL.

METHODS: Belgian deskbound university employees (n = 28, 17 women, mean age 30 ± 7.5 years, mean BMI 22.1 ± 2.0 kg/m2 ) were provided with the chair&app in three conditions: a controlled condition (following a prescribed protocol), a free-living condition (conducting usual office work for 2 hours), and an extended free-living condition (conducting usual office work for three consecutive days). Total sitting time and the number of sitting interruptions were compared between the chair&app and criterion measures (camera observation and activPAL). Criterion validity was assessed using mean differences (95% CI) and intra-class correlation coefficients (ICC; 95% CI).

RESULTS: In the controlled condition, mean sitting time and number of sitting interruptions differed between chair&app and camera observation by 2.7 (-2.4, 7.9) minutes and -8.0 (-10.4, -5.6) interruptions, respectively. For the free-living condition, there was good agreement between chair&app and camera observation for both sitting time (ICC: 0.74; 0.28, 0.93) and sitting interruptions (ICC: 0.68; 0.10, 0.91). For the extended free-living condition, there was excellent agreement between chair&app and activPAL for sitting time (ICC: 0.89; 0.49, 0.97). Meanwhile, there was poor agreement between chair&app and activPAL for sitting interruptions (ICC: 0.38; -0.04, 0.70).

CONCLUSIONS: Chair&app generally provided reliable measures of desk-based sitting. Consequently, chair&app might be useful as a self-monitoring tool in the workplace context. Further research is needed to explore its usefulness in reducing adults' desk-based sitting.