Purpose: This study aimed to examine the cross-sectional and longitudinal associations of three walking parameters (frequency, duration, and intensity) with overall mental health in older adults. Methods: A cross-sectional survey was conducted in 2014 with 1255 community-dwelling older adults aged 65 years and older in Taipei, Taiwan. Among them, 408 participants completed the one-year follow-up survey in 2015. Self-reported outdoor walking during the past 7 days was measured by asking the frequency, duration, and intensity. Metabolic equivalent (MET) values (<2.5, 2.5–<3.5, 3.5–<4.5, and ≥4.5 MET) were assigned to the four levels of speed (slow pace, average, brisk, and fast pace) based on the average walking distance per minute. Overall mental health was assessed using the Five-item Brief Symptom Rating Scale (BSRS-5). Multivariable linear regression models were conducted to explore the cross-sectional and longitudinal associations between outdoor walking and overall mental health, adjusting for socio-demographic factors, lifestyle behaviors, comorbidity and health status. Results: Among the walking parameters, only walking intensity emerged as a significant predictor of subsequent overall mental health. Multivariable regression analysis showed that light-to-moderate intensity (approximately 2.5–<4.5 METs) was significantly associated with better overall mental health at 12-month follow-up. Conclusions: Outdoor walking at light-to-moderate intensity is prospectively associated with better overall mental health in later life
