Examining Psychosocial Mediators of Exercise Behavior

Study Overview
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Brief Summary
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The purpose of this study is to examine psychosocial mediators of exercise behavior.

Detailed Description
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BACKGROUND: 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 percent 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. DESIGN NARRATIVE: The study will examine the mediating effect of theoretical constructs based on the Transtheoretical Model (TTM) and Social Cognitive Theory (SCT). The study will address the methodological, measurement, and statistical limitations of previous studies. The investigators 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. They 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. They 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, they will conduct a cost analysis to not only 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). The 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, the 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.

Official Title
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Examining Psychosocial Mediators of Exercise Behavior

Conditions
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Cardiovascular Diseases, Heart Diseases

Intervention / Treatment
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* Behavioral: Physical activity
* Behavioral: Wellness


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: In good health Living a sedentary lifestyle

Ages Eligible for Study
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Maximum Age: 100 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 1<br>Tailored print-based intervention in which participants complete questionnaires and receive tailored feedback based on responses to the questionnaires. The intervention is delivered monthly during the first month, bi-monthly during months 2 and 3, and monthly during months 4-6. The intervention is completed through the mail. | Behavioral: Physical activity<br>* Tailored print-based intervention in which participants complete questionnaires and receive tailored feedback based on responses to the questionnaires. The intervention is delivered monthly during the first month, bi-monthly during months 2 and 3, and monthly during months 4-6. The intervention is completed through the mail.<br>|
| Active Comparator: 2<br>Participants receive wellness materials delivered through the mail on the same schedule as the experimental condition. Physical activity materials are given to this group upon completion of the study. | Behavioral: Wellness<br>* Participants receive wellness materials delivered through the mail on the same schedule as the experimental condition. Physical activity materials are given to this group upon completion of the study.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Physical activity |  | Measured at baseline, 6, and 12 months |