Effects of Self-efficacy, Planning, and Self-efficacy+Planning Interventions on Body Fat Among Adolescents

Summary

This longitudinal experimental study tested the effects of three brief interventions: (1) prompting the formation of plans (or implementation intentions), (2) prompting self-efficacy beliefs, and (3) prompting planning + self-efficacy in adolescents aged 14-18 years relative to an active 'education only' control group.

It was hypothesized that participants assigned to the interventions would exhibit a smaller increase in body fat at 14-month follow-up compared to controls. The study also investigated whether the combined planning + self-efficacy intervention would have larger effects on the main outcome (body fat) than single-component interventions. Second, it was hypothesized that the effects of the intervention conditions on body fat at 14-month follow-up would be mediated by their respective psychological and behavioral constructs: self-efficacy and planning at T2 (Mediator 1), and by moderate-to-vigorous physical activity (MVPA) at T3 (Mediator 2). It was expected that the effects of the interventions including the planning component (i.e., planning intervention and self-efficacy + planning intervention) would be mediated by respective cognitions, i.e. planning, whereas the effects of the interventions including self-efficacy component (i.e., self-efficacy intervention and self-efficacy + planning intervention) would be mediated by self-efficacy. Finally, it was explored whether the effects of the intervention (both direct and indirect effects, via their respective psychological variables and MVPA) on body fat would be moderated by the presence of built PA facilities, located in the proximity of schools.

Conditions

• Adolescent Behavior

Interventions

BEHAVIORAL

Self-Efficacy

The introductory part included an abbreviated version of the education materials used in the control group. The self-efficacy materials and forms had four sections: (a) definitions of self-efficacy beliefs, (b) information on the importance of self-efficacy for goal pursuit, (c) recollecting a mastery experience, (d) persuasive statements evoking self-persuasive statements about self-efficacy beliefs. The materials ended with instructions for the following 7 days to recollect self-efficacy enhancing statements every morning. The procedures are based on a self-efficacy intervention by Luszczynska, Tryburcy et al. (2007). Group and individual components were included. Setting: secondary and high schools.

BEHAVIORAL

Planning

The introductory part included an abbreviated version of the education materials used in the control group. The planning materials and forms had four sections: (a) information on the importance of planning, including examples of how planning works and what it affects, (b) instructions of what should be included in a good plan (the when, where, and how components), (c) formulating action and coping plans. The materials ended with instructions for the following 7 days to recollect/redo plans every morning.The procedures are based on a planning intervention by Luszczynska, Sobczyk, et al. (2007). Group and individual components were included. Setting: secondary and high schools.

BEHAVIORAL

Education

Participants received a set of educational materials about types of physical activity (PA), PA intensity, exercise calorie expenditure, myths about PA, strength and endurance training, stretching, and general healthy nutrition guidelines. The materials excluded planning and self-efficacy statements. The materials ended with instructions for the following 7 days to recollect forms of MVPA every morning. Group and individual components were included. Setting: secondary and high schools.

Sponsors & Collaborators

• University of Zurich

  collaborator OTHER

• Free University of Berlin

  collaborator OTHER

• Curtin University

  collaborator OTHER

• University of Social Sciences and Humanities, Warsaw

  lead OTHER

Principal Investigators

• Aleksandra Luszczynska, PhD · University of Social Sciences and Humanities

Study Design

Allocation

RANDOMIZED

Purpose

PREVENTION

Masking

DOUBLE

Model

PARALLEL

Eligibility

Min Age

14 Years

Max Age

18 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2009-05-31

Primary Completion

2015-06-30

Completion

2015-06-30

Countries

• Poland

Study Locations