Objective The aim was to examine the effectiveness of a group-based coaching intervention on office workers' leisure-time physical activity (LTPA) levels, and to examine potential differences in effect based on age, baseline physical activity status (BPAS), education, and gender. In addition, the objective was to determine participant's perceived satisfaction with the intervention. 

Method An intervention study with a one-group design with pre-and post-tests was conducted. Through a convenience sampling method, thirty-nine participants were enrolled in the study. LTPA was measured at pre-and post-tests, and the perceived satisfaction with the intervention was measured at post-test. The intervention consisted of four group-based meetings and one phone call. Thirty-five participants were included in the analysis.  

Results The mean perceived satisfaction with the intervention was 20.1, where 25 was the highest possible score. LTPA increased significantly with a large effect size, independent of age, BPAS, education, and gender, although increasing age was correlated with lower increases of LTPA. 

Conclusion The present intervention may effectively promote LTPA among office workers, independent of age, BPAS, education, and gender, although causal inferences cannot be determined due to methodological limitations. Thus, future RCT studies are warranted to determine the potential of the current intervention in promoting LTPA among office workers.