Assessing the Effects of Interpersonal and Intrapersonal Behavior Change Strategies on Physical Activity in Older Adults: a Factorial Experiment

Abstract

Background: Little is known about which behavior change strategies motivate older adults to increase their physical activity.

Purpose: The purpose of this study was to assess the relative effects of two sets of behavior change strategies to motivate increased physical activity among older adults: interpersonal and intrapersonal.

Methods: Community-dwelling older adults (N = 102, mean age = 79) were randomized in a 2 × 2 factorial experiment to receive interpersonal (e.g., social support, friendly social comparison; no, yes) and /or intrapersonal (e.g., goal setting, barriers management; no, yes) behavior change strategies, combined with an evidence-based, physical activity protocol (Otago exercise program) and a physical activity monitor (Fitbit One™).

Results: Based on monitor data, participants who received interpersonal strategies, compared to those who did not, increased their average minutes of total physical activity (light, moderate, vigorous) per week, immediately (p = .006) and 6 months (p = .048) post-intervention. Similar, increases were observed on measures of functional strength and balance, immediately (p = .012) and 6 months (p = .003) post-intervention. The intrapersonal strategies did not elicit a significant increase in physical activity or functional strength and balance.

Conclusions: Findings suggest a set of interpersonally oriented behavior change strategies combined with an evidence-based physical activity protocol can elicit modest, but statistically and clinically significant, increases in older adults' physical activity and functional strength and balance. Future research should replicate these findings and investigate the sustained quantity of physical activity elicited by these strategies and their impact on older adults' quality of life and falls. Trial Registration The ClinicalTrials.gov registration identifier is NCT02433249.

Keywords: Accidental falls; Aged; Behavioral intervention; Factorial design; Motivation; Multiphase optimization strategy; Physical activity.

Conflict of interest statement

Authors of this manuscript, McMahon, Lewis, Oakes, Wyman, Guan, and Rothman, declare that they have no conflicts of interest. See full Conflict of Interest and Ethical Compliance statement in file titled, Compliance with Ethical Standards

Figures

Figure 1

Intervention Conceptual Model

Figure 2

Consort Flow Diagram

Figure 3

Marginal Means of the interpersonal behavior change strategy set on average weekly minutes of total physical activity (light, moderate, vigorous intensities) captured via physical activity monitor (Fitbit One™) immediately post-intervention and 6 months post-intervention

Figure 4

Marginal Means of the intrapersonal behavior change strategy set on average weekly minutes of total physical activity (light, moderate, vigorous intensities) captured via physical activity monitor (Fitbit One™) immediately post-intervention and 6 months post-intervention.