Effects of 12-week exercise on Meteorin-like levels, inflammation, and functional capacity in older adults: Korean national aging project randomized controlled study.

Purpose: Meteorin-like protein (Metrnl) is involved in regulating inflammation, metabolism, and muscle regeneration, making it a promising therapeutic target. Building on prior research, we investigated how exercise-induced changes in Metrnl relate to inflammatory markers, physical function, and cognitive performance. This randomized controlled trial examined the effects of a 12-week exercise intervention on circulating Metrnl, a novel biomarker, in 90 community-dwelling older adults (≥ 65 years).

Methods: Participants were randomized into a walking group (WG), a combined resistance and walking group (RWG), or an active control group (CG). Intervention groups engaged in moderate-intensity exercise; walking based on age-specific step goals and resistance training twice weekly. Blood samples and assessments of physical and cognitive function were collected pre- and post-intervention.

Results: 79 participants successfully completed the study. After 12 weeks, serum Metrnl levels significantly increased in both RWG and WG compared to CG (WG vs. CG: p = .002; RWG vs. CG: p = .004). Metrnl changes were correlated with improvements in inflammatory markers (IL-6, p = .048; TNF-α, p = .040), physical activity (p = .041), and physical function (Timed Up & Go, p = .004; Five Times Sit to Stand Test, p = .008). Stronger associations were observed in the RWG, including cognitive gains (Stroop test, p = .040), enhanced handgrip strength (p = .036), and reduced fat mass (pp= .021). Timed Up & Go and Five Times Sit to Stand Test were the strongest predictors of Metrnl changes.

Conclusion: These findings highlight Metrnl's potential as a biomarker linking exercise to reduced inflammation and improved physical and cognitive outcomes in older adults, supporting its relevance in developing targeted exercise-based therapies.