Examining Psychosocial Mediators of Exercise Behavior

描述（由申请人提供）：缺乏运动与许多健康问题有关，包括心血管疾病、高血压和癌症的风险增加。尽管久坐不动的生活方式对健康造成了影响，但只有25%的美国人达到了建议的体育锻炼水平。研究人员假设，基于理论的干预措施通过改变被认为对行为改变很重要的理论结构（即潜在的中介），如自我效能感（即对身体活动能力的信心），有效地影响身体活动行为。不幸的是，以前的研究通常未能充分测试理论结构的中介作用，使用适当的统计中介分析，由主要的行为科学家和统计学家推荐。本研究的目的是基于跨理论模型（TTM）和社会认知理论（SCT）来检验理论构念的中介作用。我们提出的研究将解决以往研究的方法学、测量和统计局限性。我们将随机分配420名健康的久坐不动的人到基于理论的身体活动干预组或接触对照组。身体活动行为和潜在的中介将在12个月内每月进行评估。我们假设，基于TTM和SCT的构式（即行为过程、认知过程、自我效能和决策平衡）将中介群体分配（干预vs.接触控制）与身体活动行为之间的关系，因此，在控制中介因素的情况下，干预对身体活动行为的影响相对于接触对照组会减弱。我们还将研究不同人口群体（如年龄、性别）的特定中介的重要性，这将有助于为这些群体创造更有效的干预措施。最后，我们将进行成本分析，不仅告知政策制定者在我们的研究中提供干预措施的成本，而且还估计提供干预措施的每个组成部分（即中介）的成本。我们的分析将估算在本研究中纳入影响介质和身体活动的活性成分的未来精细干预措施的成本。总之，我们提出的研究将确定哪些介质（即理论结构）对增加身体活动最有效，这将对公共卫生产生重要影响，因为这可能导致更有效和更低成本的干预措施。

DESCRIPTION (provided by applicant): Physical inactivity is related to many health problems including increased risk of cardiovascular disease, hypertension, and cancer. Despite the health consequences of a sedentary lifestyle, only 25% of Americans meet the recommended levels of physical activity. Researchers postulate that theory-based interventions effectively influence physical activity behavior by changing theoretical constructs believed to be important for behavior change (i.e., potential mediators), such as self-efficacy (i.e., confidence in one's ability to be physically active). Unfortunately, previous studies have generally failed to adequately test the mediating effect of theoretical constructs using appropriate statistical mediator analyses as recommended by leading behavioral scientists and statisticians. The objective of our application is to examine the mediating effect of theoretical constructs based on the Transtheoretical Model (TTM) and Social Cognitive Theory (SCT). Our proposed study will address the methodological, measurement, and statistical limitations of previous studies. We will randomly assign 420 healthy sedentary individuals to either a theory-based physical activity intervention or a contact control group. Physical activity behavior and the potential mediators will be assessed monthly over 12 months. We hypothesize that constructs based on The TTM and SCT (i.e., behavioral processes, cognitive processes, self-efficacy, and decisional balance) will mediate the relationship between group assignment (intervention vs. contact control) and physical activity behavior, such that the effect of the intervention on physical activity behavior relative to the contact control group will be attenuated when controlling for the mediators. We will also examine the importance of particular mediators for different population groups (e.g., age, gender), which will help to create more effective interventions for these groups. Finally, we will conduct a cost analysis to not only to inform policy makers of the cost of delivering the intervention within our study but also to estimate the cost of delivering each component of the intervention (i.e., mediator). Our analysis will estimate the cost of future refined interventions that incorporate those active components that affect the mediators and physical activity in this study. In summary, our proposed study will identify which mediators (i.e., theoretical constructs) are most effective for increasing physical activity, which will have an important public health impact given that this will likely lead to more efficacious and less costly interventions.