Physical activity and mood in daily life – a multi-burst ambulatory assessment study disentangling state and trait components of within-person associations

$\textbf{Background}$
Physical activity (PA) and mood are associated in daily life. Prior studies showed that these associations are moderated by contextual factors (e.g., weather conditions) and differ between individuals. Yet, it remains unclear to what extent associations between PA and mood reflect stable, person-specific characteristics or fluctuate over time.

$\textbf{Methods}$
We examined the temporal stability of within-person PA–mood associations derived from three one-week ambulatory assessments across three consecutive years in 65 adolescents and young adults. Mood was assessed via e-diaries, and PA was recorded with accelerometers. Multilevel models estimated the effects of preceding PA on mood. Between-person differences and within-person stability were quantified by random-effect variances and correlations across participants and weeks.

$\textbf{Results}$
As hypothesized, PA was positively associated with subsequent energetic arousal (β = 4.88, p < .001) and valence (β = 1.27, p = .042) but negatively with calmness (β = −1.86, p = .003). Intraclass Correlation Coefficients indicate that 64%, 44%, and 80% of variance of the weekly PA-mood associations of individuals are attributable to between-person differences, while 36%, 56%, and 20% of variance are accounted for by within-person fluctuations in associations of PA with energetic arousal, valence, and calmness, respectively.
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$\textbf{Conclusions}$
For the first time, we show that PA–mood associations reflect a combination of both stable ‘trait’ components (between subjects) and ‘state’ variability (within subjects). Both have important implications for personalized and context-sensitive intervention approaches, such as just-in-time adaptive interventions. Future research is needed to unravel which situational components and person characteristics shape the variability of associations.