Everyday Associations Between Older Adults' Physical Activity, Negative Affect, and Cortisol

Objective: Experimental research has demonstrated that individuals with higher physical activity levels show reduced cortisol responses to psychosocial stress. The present study takes this research out of the lab and it extends these findings by investigating whether older adults' physical activity also moderates everyday-life within-person associations between momentary negative affect and concurrent salivary cortisol. Methods: A sample of 162 older adults aged 60 to 87 years (M age = 71 years; 50% women; 57% Caucasian) completed affect assessments and provided concurrent salivary cortisol samples 4 times per day over 7 consecutive days. Hip-worn accelerometers objectively recorded step counts during this period. Data were analyzed using multilevel models, controlling for diurnal cortisol changes and relevant individual difference variables (e.g., age, gender, body mass index, person-average negative affect). Results: Increased momentary negative affect was associated with higher concurrent cortisol levels. Average daily steps moderated these negative affect-cortisol associations in such a way that participants who exhibited higher average daily steps showed a less pronounced increase in momentary cortisol in moments when they reported higher momentary negative affect. Conclusions: Individual differences in older adults' average daily steps may buffer cortisol secretion in moments of heightened negative affect. Findings underpin that physical activity modulates associations of negative affect with neuroendocrine activity in everyday life. Consequently, physical activity promotion may mitigate negative health ramifications associated with cortisol dysregulation in old age.