Automatic vs. rational motives for adolescent physical activity: an ecological momentary assessment study

Objective The current study seeks to examine rational motivational variables central to self-determination theory (i.e., perceived competence, family social support, friend social support, autonomous motivation, controlled motivation, and amotivation) as moderators of the relationship between automatic motives (i.e., momentary affective states, fatigue, and energy) and physical activity (moderate-to-vigorous physical activity and sedentary behavior). Methods We conducted a 20-day ecological momentary assessment (EMA) study, in which 100 adolescents aged 13–18 years old were recruited locally February 2016 to March 2017 and were asked to indicate baseline social support, motivation, and competence for physical activity. Subsequently, participants wore an Actigraph accelerometer 24 h per day and answered EMA surveys assessing automatic motives 4 times per day using time-based signaling. Results There was a significant interaction between within-person positive affect and amotivation as a predictor of moderate-to-vigorous physical activity (MVPA) ( b = −0.02, p < 0.05) with 95% CI [−0.04, −0.01] and sedentary time ( b = 0.10, p < 0.01) with 95% CI [0.04, 0.16]. There was also a significant interaction between within-person negative affect and amotivation as a predictor of sedentary time ( b = −0.08, p < 0.05) with 95% CI [−0.14, −0.01]. Within-person fatigue interacted with friend social support ( b = 0.05, p < 0.01) with 95% CI [0.02, 0.08], amotivation ( b = 0.03, p < 0.05) with 95% CI [0.003, 0.06], and controlled motivation ( b = −0.03, p < 0.01) with 95% CI [−0.05, −0.01] in relation to MVPA. Conclusions Overall, findings from this study suggest that rational and automatic motives are intertwined and should be explored together as targets for physical activity intervention efforts.