Level and sociodemographic correlates of maximum acceptable physical activity increase among Japanese adults

Goal setting is an important step in planning physical activity promotion strategies. Based on the dose-response relationships between physical activity and health and the goal-setting theory, setting higher goals without exceeding people's acceptance is desirable. Understanding maximum acceptance of physical activity increases is helpful for enabling such goal setting. Nonetheless, the level of maximum acceptance of physical activity increase and its sociodemographic differences remain unclear. This study examined the level and sociodemographic correlates of maximum acceptable physical activity increase among Japanese adults.

A web-based cross-sectional questionnaire survey was conducted with 2259 Japanese adults aged 20-64 years. Based on the Capability, Opportunity, Motivation, and Behavior model, the acceptable time for increasing physical activity in a day was examined from three perspectives: capabilities, opportunities and motivations. For motivation, two definitions were employed: definition I regarded unchanged motivation as acceptable, and definition II regarded it as unacceptable. The maximum acceptable physical activity increase was identified by combining the responses of these subcomponents. This study measured sociodemographic factors such as gender, age, current marital status, current working status, educational background, annual household income and current physical activity duration.

The means (95% confidence intervals) and standard deviations of maximum acceptable physical activity increase were 17.0 (16.3-17.7) and 16.9 min per day in definition I and 9.0 (8.4-9.6) and 13.9 min per day in definition II. Across both definitions, multiple regression analyses showed that younger age, greater levels of annual household income and longer current physical activity duration were significantly associated with longer maximum acceptable physical activity increases.

From the findings, an increase in physical activity of approximately 10-15 min per day might be an important option in goal setting, and setting higher goals would be feasible for younger adults, adults with higher household incomes, and physically active adults.