Effects of an "Active-Workstation" Cluster RCT on Daily Waking Physical Behaviors.

PURPOSE Evaluate the effects of sit-to-stand and treadmill desks on sedentary behavior during a 12-month, cluster-randomized multi-component intervention with an intent-to-treat design in overweight office workers. METHODS Sixty-six office workers were cluster-randomized into a: control (N=21; clusters=8), sit-to-stand desk (N=23; clusters=9) or treadmill desk (N=22; clusters=7) group. Participants wore an activPALTM accelerometer for 7 days at baseline, month-3, month-6 and month-12 and received periodic feedback on their physical behaviors. The primary outcome was total daily sedentary time. Exploratory outcomes included total daily and workplace sedentary, standing and stepping time, and the number of total daily and workplace sedentary, standing and stepping bouts. Intervention effects were analyzed using random intercept mixed-linear-models accounting for repeated measures and clustering effects. RESULTS Total daily sedentary time did not significantly differ between- or within-groups after 12-months. Month-3 gains were observed in total daily and workplace standing time in both intervention groups (sit-to-stand desk: mean Δ±SD= 1.03±1.9 h/day and 1.10±1.87 h at work; treadmill desk: mean Δ±SD= 1.23±2.25 h/day and 1.44±2.54 h at work). At month-3 the treadmill desk users stepped more at the workplace than the control group (mean Δ±SD= 0.69±0.87 h). Month-6 gains in total daily stepping were observed within the sit-to-stand desk group (mean Δ±SD= 0.82±1.62 h/day) and month-3 gains in stepping at the workplace were observed for the treadmill desk group (mean Δ±SD= 0.77±0.83 h). These trends were sustained through month-12 in only the sit-to-stand desk group. CONCLUSIONS Active-workstation interventions may cause short-term improvements in daily standing and stepping. Treadmill desk users engaged in fewer sedentary bouts but sit-to-stand desks resulted in more frequent transitions to upright physical behaviors.