Validation of the W@WApp + MetaWearC sensor to monitor occupational sitting, standing and stepping in office employees. (Preprint)

BACKGROUND Replacing occupational sitting time with active tasks has several proposed health benefits for office employees. Smartphones and motion sensors can provide objective information in real time on occupational sitting behaviour. However, the validity and feasibility of using mHealth devices to quantify and modify occupational sedentary time is unclear. OBJECTIVE To validate the new Walk@Work-Application (W@WApp) - including an external motion sensor (MetaWearC) attached to the thigh - for measuring occupational sitting, standing and stepping in free-living conditions against the activPAL3M. METHODS Twenty office-workers, 16 females (80%, 39.5±8.1 years old) downloaded the W@WApp to their smartphones, wore a MetaWearC attached to their thigh in a tailored band and wore the activPAL3M for three to eight consecutive working hours. Differences between both measures were examined using paired samples t-tests and Wilcoxon signed-rank tests. Agreement between measures were examined using concordance correlation coefficients (CCC), 95% confidence intervals, Bland-Altman plots (mean bias, 95% Limits of Agreement - LoA) and equivalence testing techniques. RESULTS The median recording time for the W@WApp+MetaWearC and the activPAL3M were 237.5±132.8 and 240.0±127.5 minutes respectively (P<.001). No significant differences between sitting (P=.53), standing (P=.12) and stepping time (P=.61) were identified. CCC identified substantial agreement between both measures for sitting (CCC=0.98, 95% CI: 0.96, 0.99), moderate agreement for standing (CCC=0.93, 95% CI: 0.81, 0.97) and poor agreement for stepping (CCC=0.74, 95% CI: 0.47, 0.88). Bland-Altman plots indicated that sitting time (mean bias = -1.66 minutes, 95% LoA: -30.37, 20.05) and standing time (mean bias = -4.85 minutes, 95% LoA: -31.31, 21.62) were under-reported. For stepping time, a positive mean bias of 1.15 minutes (95% LoA: -15.11, 17.41) was identified. Equivalence testing identified that the estimates obtained from the W@WApp+MetaWearC and the activPAL were considered equivalent for all variables excluding stepping time. CONCLUSIONS The W@WApp+MetaWearC is a low-cost tool with acceptable levels of accuracy that can objectively quantify occupational sitting, standing, stationary time and upright time in real-time. Due to the feedback available to users, this tool could positively influence occupational sitting behaviours in future interventions. CLINICALTRIAL Registration Clinical Trials: NCT04092738.