Objective: This 14-day daily diary study tested a dual-process model of motivation to determine the between-person (time-invariant) and within-person (time-varying) processes associated with older adults' daily sedentary behavior. This model integrated the health action process approach (HAPA) with research on habit strength.
Method: Older adults (n = 100) answered questions regarding their motivation and behavior at the beginning and end of each day, respectively. Participants also wore ActivPAL3 activity monitors for the duration of the study.
Results: Multilevel models predicting behavior revealed that sedentary behavior was (a) negatively associated with planning to reduce sedentary behavior at the within-person (but not the between-person) level, and (b) positively associated with sedentary behavior habit strength. Plans to limit sedentary behavior were (a) positively associated with task self-efficacy at the within-person level, but (b) negatively associated at the between-person level, and (c) positively associated with intentions at the between- and within-person level. Intentions to limit sedentary behavior were (a) positively associated with task self-efficacy at the between and within-person level, but (b) not associated with light-intensity physical activity outcome expectations, sedentary behavior risk perceptions, or sedentary behavior habit strength.
Conclusions: This study was the first to systematically investigate a combination of controlled and automatic processes that are associated with daily fluctuations in older adults' sedentary behavior. Interventions aiming to reduce sedentary behavior in older adults should target the motivational constructs identified in this study to provide the best chance for behavior change.
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