Psychophysiological Effects of Green Exercise in Outdoor Green vs. Indoor Control

Study Overview and Theoretical Framework This randomized controlled trial (RCT) aims to investigate the psychophysiological restorative effects of green exercise. The study is grounded in Attention Restoration Theory (ART) and Stress Recovery Theory (SRT). It specifically tests a "Sensory-to-Appraisal" model, which proposes that the restorative benefits of nature are driven by an initial stage of objective sensory information harvesting, followed by subjective restorative appraisal. Experimental Design A total of 80 healthy young adults (aged 18-35) were recruited and randomly assigned to one of two groups with a 1:1 allocation ratio. 1. The Outdoor Green group: Participants performed a standardized 30-minute walk along a pre-defined route in a forest park environment. 2. The Indoor Control group: Participants performed a 30-minute walk on a treadmill in a controlled laboratory setting (windowless room, neutral environment) at a self-selected moderate pace to match the physical intensity of the outdoor group. Experimental Procedure The experiment followed a five-stage longitudinal design. 1. Baseline (T0): Collection of demographic data, Nature Relatedness (NR) scales, and initial physiological/psychological measurements. 2. Stress Induction: Participants underwent a cognitive stressor to induce mental fatigue and psychological stress. 3. Intervention (T1): The 30-minute walking intervention in the assigned environment. 4. Post-Intervention (T2): Immediate post-test measurements including sensory harvesting (NSSI), perceived restorativeness (PRS), and emotional states. 5. Recovery Monitoring: Follow-up assessment of cognitive function and physiological recovery markers. Key Measures 1. Sensory Harvesting: Measured by the Nature Sensory Sensitivity Index (NSSI), a tool designed to quantify the objective capture of environmental stimuli. 2. Psychological Appraisal: Evaluated via the Perceived Restorativeness Scale (PRS). 3. Cognitive Function: Assessed through the Digit Span Task (Forward and Backward) to measure working memory and directed attention. 4. Affective States: Measured using the Profile of Mood States (POMS) to calculate Total Mood Disturbance (TMD) and self-esteem scales. 5. Physiological Response: Objective stress recovery was monitored via salivary cortisol levels and Heart Rate Variability (HRV), specifically the RMSSD (Root Mean Square of Successive Differences) to assess parasympathetic activation. Statistical Analysis The study uses a serial mediation model to analyze how the environment intervention influences restorative outcomes through the sequential mediation of NSSI and PRS. Mixed-model ANOVAs are used to compare between-group differences across time points.