Not just a walk: Mood-dependent effects of walking in a park on the mucosal immunity and psychological states in postmenopausal women

Background Walking is known to benefit emotional well-being and physical health, yet its effects on the psychoneuroimmune system remain unclear. Psychological distress is common in postmenopausal women. Objectives This study examined the influence of mood on psychoneuroimmune responses to walking in this population. Methods Twenty-four postmenopausal women were stratified into happy (n = 12) and unhappy (n = 12) groups based on baseline scores of the Happiness and Life Satisfaction Scale. All participants completed a single 60-min walking session in a park. Pre- and post-walking assessments included heart rate variability (HRV), blood pressure, and salivary biomarkers (cortisol, α-amylase, lactoferrin, immunoglobulin A, total protein, and mitochondrial DNA [mtDNA]). Psychological status was evaluated using the Profile of Mood States (POMS). Results Salivary α-amylase/total protein (TP) significantly increased in both groups, while lactoferrin/TP rose only in the unhappy group. Salivary mtDNA decreased in both groups, with a larger reduction in the unhappy group. Following walking, both groups showed reductions in systolic blood pressure and RR intervals, along with an elevation in heart rate. At both measurement time points, the unhappy group consistently presented higher mean heart rate and lower root mean square of successive differences (RMSSD) compared with the happy group. Psychological outcomes improved in both groups. The unhappy group had greater reductions in confusion, fatigue, tension, and anger, whereas the happy group showed increased vigor and self-esteem, along with reduced anger and depression. Conclusions A single 60-min park walk modulated mucosal immunity and enhanced psychological well-being in postmenopausal women. Baseline mood influenced the magnitude of responses, with greater benefits observed in the unhappy group, highlighting the therapeutic potential of walking in natural environments.