Using "stages of behavioral change" constructs to measure the short-term effects of a worksite-based intervention to...

We evaluated a three-level incentive program to promote regular, moderate physical activity among employees working in a federal agency. The objective was to assess the short-term effects of the intervention by examining the stages people go through as they attempt to make permanent changes in physical activity. Indicators of the process by which changes in physical activity take place were based on a modified version of the Transtheoretical Model of Behavior. A one-group pretest/posttest design was used to ascertain which of the stages the 1,192 participants were in both before and after the intervention. Analysis indicated that, of the 1,192 participants, 6.5% regressed one or more stages, 30.3% did not regress or progress from one stage to another, 27.7% remained in the maintenance stage, and 35.4% progressed one (21.1%) or more (14.3%) stages during the 50-day intervention. Among those who progressed, the most common change was from preparation to late preparation (20.8%) and from late preparation to action (19.4%). Findings reinforce the notion that the stages of change concept can serve as indicators of the change process which in turn, can be used as evidence of the short-term effectiveness of interventions. Findings also indicate this type of intervention holds promise for increasing physical activity among willing participants of a worksite population.