Effects of Barefoot Walking in Urban Forests on CRP, IFNγ, and Serotonin Levels.

BACKGROUND/OBJECTIVES: This study investigated the effects of barefoot walking on an urban forest path on participants' C-reactive protein (CRP), interferon gamma (IFNγ), and serotonin levels, which are associated with feelings of well-being. METHODS: Participants in the walking program included 62 consenting adults, divided into a sneaker-wearing and barefoot group (each N = 31). The program comprised 20 sessions, each consisting of a 90 min 4.4 km walk at a 50-70% target heart rate, held four times per week for 5 weeks. Physiological measurements were taken from pre-program saliva samples and after 10 and 20 sessions, respectively. RESULTS: The sneaker-wearing group showed a consistent CRP increase, with levels reaching statistical significance after 20 sessions. In the barefoot group, CRP increased up to Session 10 but was lower than at the end of Session 20. The analysis of those with an initial CRP above 100 pg/mL showed that CRP was statistically significantly lower in the barefoot (N = 14) than in the sneaker-wearing (t = -0.048, p = 0.963) group after 20 sessions compared to before the program (t = 3.027, p = 0.010). IFNγ increased in both groups up to Session 10 but showed minimal change between Sessions 10 and 20. Serotonin was statistically significantly higher after 20 sessions than before the program in the barefoot group (t = -2.081, p = 0.046). CONCLUSIONS: Barefoot walking on forest trails is effective for people with above-normal inflammation, increasing serotonin levels.