Physical activity motivation across stages of change in older adults

Abstract

Objectives: The objectives of this project were to: 1) establish what factors exist within collected data from a physical activity motivational measure developed from the perspective of self-determination theory (Deci & Ryan, 1985); and 2) determine the key variables, among these six factors, which differentiate exercise stages of change (Prochaska & DiClemente, 1983) in older adults. Methods: A clinic based sample of 645 adults 50-79 years old (Mage = 63.8) provided survey data. Measures included exercise stage-of-change scale (Marcus, Rossi, Selby, Niaura, & Abrams, 1992b ), 44 items from the Exercise Motivations Inventory - Revised (EMI-2: Markland & Ingledew, 1997), and demographic profiles. In Study #1, the psychometric properties of the EMI-2 were examined using exploratory factor analysis, including principal components analyses with orthogonal rotation. In Study #2, MANOVA tested for group differences between three activity levels (Inactives, Actives, Sustained Maintainers) while adjusting for interactions between activity level, age, and gender, followed up by both post-hoc multiple comparisons univariate and discriminant function analyses. Results: Exploratory factor analysis yielded six factors/subscales consisting of 37 items with eigenvalues greater than 1.0, accounting for 70.3% of the total variance. The six factors were labeled Health & Fitness, Social/Emotional Benefits, Weight Management, Stress Management, Enjoyment, and Appearance. Cronbach's reliability coefficients ranged from .86 to .94. Pearson correlations between subscales ranged from .36 to .68. Gender invariance was also demonstrated. Study #2 results of MANOVA yielded main effects for activity level, gender, and age (p < .001), but no interaction effects among these three factors. Follow-up analyses between paired activity level groups indicated that enjoyment, associated with intrinsic motivation, contributed to differentiating activity levels more than any extrinsic motives. Self-determined extrinsic motives of health and fitness, and social/emotional benefits also discriminated activity levels in certain population subgroups. Nonself-determined extrinsic motives of weight management and appearance did not differ between activity levels. Conclusions: Intrinsic motivation and self-determined extrinsic motivation differentiate higher from lower activity levels in older adults. Results support future research that examines self-determination's role as a mediator of exercise behavior change, and its utility in tailored interventions to.effect exercise behavior change in older adults.