The escalating pace of urbanization has made chronic stress and attentional fatigue significant public health challenges. This study employed a randomized controlled trial (\(N=80\)) to investigate the psychophysiological restorative effects of a standardized 30-minute walk in an urban forest environment (Outdoor Green) compared to a laboratory setting (Indoor Control). Cognitive function was assessed via the Digit Span Task, affective states were evaluated using the Profile of Mood States (POMS) and self-esteem measures, and physiological stress responses were objectively quantified through salivary cortisol and heart rate variability (HRV-RMSSD). Results indicated that the Outdoor Green group exhibited significantly greater improvements in directed attention (\(p <0.001\)) and total mood disturbance (\(p <0.001\)) compared to the Indoor Control group. Physiologically, the outdoor group showed a more pronounced reduction in salivary cortisol (interaction \(p =0.001\)) and a greater increase in parasympathetic activity (HRV-RMSSD, interaction \(p <0.001\)). Furthermore, mediation analysis revealed that the alleviation of negative affective states partially mediated the relationship between environmental exposure and cognitive restoration. These findings demonstrate that green exercise exerts synergistic benefits across cognitive, affective, and physiological domains, providing robust evidence for nature-based interventions as effective strategies for mental health promotion.
