Background. Excessive sitting is an increasing concern in working life. Negative health effects may, to some extent, be mitigated by interrupting prolonged sitting by standing or more active behaviours, like walking. Alternations between these behaviours may also influence variation in neck-shoulder-arm exposures, and thus musculoskeletal disorder risks. This study examined time spent sitting, standing and active among office workers, and determined the extent to which these behaviours differed by gender and age.

Methods. Ninety-nine workers at a Swedish government agency (50/49 men/women; mean(SD) age 47.1(9.0) years) wore a thigh accelerometer (Actigraph GT3X) for five working days. Data were processed to give the percentage of time spent sitting in short (<30 min) and long (≥30 min) bouts, in standing, and in more active behaviours. In adding up to 100%, such data are constrained and inherently dependent. This requires further examination to be performed using Compositional Data Analysis (CoDA). Thus, Isometric Log-transformed Ratios were constructed, describing sitting vs. non-sitting (sit/nonsit), short-bout vs. long-bout sitting (shortsit/longsit), and standing vs. active (stand/active). These ratios were examined for pairwise correlations, and for associations with gender and age.

Results. On average, workers spent 28.9%, 42.2%, 21.6%, and 7.3% time in shortsit, longsit, standing, and active. Sit/nonsit correlated negatively with shortsit/longsit (r=–0.49) and stand/active (r=–0.64); shortsit/longsit correlated positively with stand/active (r=0.19). Gender showed small associations with all three ratios (partial-ƞ²=0.01-0.03; p=0.08-0.43). Stand/active increased with increasing age (partial-ƞ²=0.07; p=0.01), while sit/nonsit and shortsit/longsit were very weakly associated with age (partial-ƞ²=0.01 and 0.01; p=0.26 and 0.40).

Conclusions. Workers spending more time sitting also spent a larger part of that time in long, uninterrupted sitting bouts. However, when not sitting, these workers were more physically active than workers who sat less. These behaviours differed little by gender and age, besides older workers being relatively less active during non-sitting periods.