Background: This study documents and compares temporal patterns of physical behaviours, assessed using accelerometry, on working and non-working days among normal-weight (body mass index [BMI] <25 kg/m2) and overweight (BMI ≥25 kg/m2) office workers who were either working exclusively at the office (WAO) or exclusively from home (WFH) during the COVID-19 pandemic.

Methods: In this cross-sectional study, behaviours were measured over 7 days using a thigh-worn accelerometer in 43 workers WAO (21 normal-weight and 22 overweight) and 73 workers WFH (33 normal-weight and 40 overweight). 24-hour behaviours were completely described in terms of sitting in short (≤5 min), moderate (>5 and ≤30 min) and long bouts (>30 min), non-sitting in short (≤5 min) and long bouts (>5 min), and time-in-bed. These behaviour compositions were transformed into five isometric log-ratios (ilr) coordinates according to compositional data analysis procedures. Differences between workplace (WAO vs. WFH) and BMI groups (normal-weight vs. overweight) were tested using ANCOVA with adjustment for age and gender.

Results: Compared to workers WAO, workers WFH spent more time-in-bed relative to time awake during working days, more time sitting relative to non-sitting, less time in short bouts of sitting relative to moderate and long bouts, less time in moderate bouts of sitting relative to long bouts, and more time non-sitting in short bouts relative to long bouts. Effect sizes [ηp2] were between 0.05 and 0.21 and p-values between <0.001 and 0.04. Irrespective of workplace, overweight workers spent less time sitting in short relative to moderate and long bouts (ηp2=0.06, p=0.01) than normal-weight workers, while differences in the other ilr coordinates were insignificant. During non-working days, behaviours did not differ significantly by workplace, while overweight workers spent more time sitting relative to non-sitting (ηp2=0.10, p<0.001), less time sitting in short relative to moderate and long bouts (ηp2=0.13, p<0.001), and less time sitting in moderate relative to long bouts (ηp2=0.04, p=0.03) than normal-weight workers. We found no interactions between workplace and BMI.

Conclusions: Our findings suggest that WFH and being overweight predispose to more time sitting and less temporal variation in behaviours, thus reinforcing that these workers could likely benefit from interventions to reduce prolonged sitting time and increase variation.