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Guangyu Zhou, Dongmei Wang, Nina Knoll and Ralf Schwarzer

Background:

Often, motivation to be physically active is a necessary precondition of action but still does not suffice to initiate the target behavior. Instead, motivation needs to be translated into action by a self-regulatory process. Self-efficacy and planning are considered to be useful constructs that help to facilitate such translations.

Objective:

The aim is to examine the roles of motivation, planning, and self-efficacy as well as the mechanisms that operate in the change of physical activity levels.

Methods:

In a longitudinal observation study with 249 young adults, self-efficacy, planning, motivation, and physical activity were assessed at 2 points in time, 3 months apart.

Results:

Planning served as a mediator between self-efficacy and physical activity, controlling for baseline activity. In addition to this indirect effect, a moderator effect was found between self-efficacy and stages of change on planning. The mediation operated only in motivated, but not in unmotivated students.

Conclusions:

A mediation from self-efficacy via planning to physical activity seems to be likely only when people are motivated to become more active.

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Benjamin Reyes Fernández, Esteban Montenegro Montenegro, Nina Knoll and Ralf Schwarzer

Background:

Self-efficacy, action control, and social support are considered to influence changes in physical activity levels in older adults. This study examines the relationship among these variables and explores the putative mediating and moderating mechanisms that might account for activity changes.

Methods:

A longitudinal study with 54 older adults (≥ 50 years of age) was carried out in Costa Rica. In a moderated mediation analysis, action control was specified as a mediator between self-efficacy and physical activity, whereas social support was specified as a moderator between self-efficacy and action control. Baseline physical activity, age, and sex were specified as covariates.

Results:

Action control mediated between self-efficacy and physical activity. An interaction between social support and self-efficacy on action control pointed to a synergistic effect at the first stage of the mediating process.

Conclusions:

The effect of self-efficacy on physical activity was partly explained by action control, providing evidence of action control as a proximal mediator of physical activity. Moreover, the moderator role of social support was confirmed: high social support appeared to compensate for low levels of self-efficacy.