Muscle-brain axis mechanisms linking community-based exercise to cognitive function in older adults: A five-arm randomized controlled trial

OBJECTIVE: To compare community-feasible exercise effects on cognition and explore muscle-brain axis mechanisms in older adults. METHODS: In this a single-blind, five-arm randomized controlled trial, participants were allocated to 12-form Chen-style Tai Chi (CTC12), 24-form Yang-style Tai Chi (TC24), square dancing (SD), walking, or control for 12 weeks (two sessions/week). Global cognition was assessed using Beijing Chinese MoCA. Body composition was evaluated using multifrequency bioimpedance: skeletal muscle mass (SMM), fat mass (FM), total body water, protein mass and basal metabolic rate (BMR). Physical performance was assessed using Short Physical Performance Battery (SPPB), maximal handgrip strength (HGS). Fasting interleukin-6 (IL-6) levels and other blood biomarkers were also measured. RESULTS: 113 participants completed the intervention (mean age 62.3 years; 79.6% female). After 12 weeks training, MoCA scores were improved in CTC12 group (n = 22, Δ = +0.46, p = 0.0045) and SD group (n = 22, Δ = +0.50, p = 0.0046), with no change in TC24 group (n = 23), walking group (n = 23), and control group (n = 23). Physiologically, CTC12 group increased SMM and BMR with small SPPB/HGS gains and showed a significant reduction in IL-6 levels; SD group reduced BMI and FM and increased BMR and SPPB; TC24 group increased BMR only; walking showed no measurable changes. For correlation analyses, ΔMoCA was positively associated with ΔSMM (p = 0.014) and ΔBMR (p = 0.004) in the CTC12 group, and negatively associated with ΔBMI (p = 0.002) and ΔFM (p = 0.002) in the SD group. CONCLUSIONS: CTC12, SD were associated with modest cognitive gains and distinct physiological patterns potentially linked to the muscle-brain axis, which may help guide exercise choices for older adults.