How Exercise Unites Brain, Muscle, and Liver to Fight Aging and Neurodegeneration
A 2025 narrative review maps the molecular crosstalk behind exercise's systemic anti-aging effects across the brain–muscle–liver axis.
Summary
This 2025 narrative review synthesizes evidence that exercise slows aging and neurodegeneration by coordinating inter-organ signaling across the brain, muscle, and liver. Key mechanisms include AMPK/PGC-1α-driven mitochondrial biogenesis in muscle, myokine release (BDNF, IL-6) that supports neuronal survival, hepatic SIRT1 activation improving lipid metabolism and insulin sensitivity, and NF-κB suppression reducing neuroinflammation. Exercise also enhances autophagy to clear toxic aggregates like amyloid-beta and alpha-synuclein, epigenetically upregulates Nrf2 antioxidant pathways, and synchronizes circadian rhythms. The authors argue these multi-tissue adaptations position exercise as a pleiotropic, systems-level intervention superior to single-organ pharmacologic approaches for aging populations.
Detailed Summary
Aging drives progressive dysfunction across multiple organ systems simultaneously, creating metabolic dysregulation, chronic low-grade inflammation (inflammaging), and vulnerability to neurodegenerative diseases like Alzheimer's (AD) and Parkinson's (PD). Traditional therapeutic strategies tend to target single organs or pathways; this 2025 narrative review proposes the brain–muscle–liver axis as a unified mechanistic framework explaining how exercise exerts broad, coordinated anti-aging effects.
The authors conducted a systematic literature search across PubMed, Scopus, Web of Science, and Google Scholar, covering peer-reviewed studies published between 2000 and 2024. Inclusion criteria prioritized RCTs, cohort studies, animal models, and high-quality reviews relevant to exercise, aging, neurodegeneration, and metabolic regulation. Evidence quality was evaluated using a modified GRADE framework.
In skeletal muscle, exercise activates AMPK and PGC-1α signaling to enhance mitochondrial biogenesis and oxidative capacity, restoring fatty acid oxidation and glucose metabolism. Crucially, contracting muscles secrete myokines—including BDNF and IL-6—that cross into circulation and reach the brain, promoting neuronal survival, synaptic plasticity, and neurogenesis in the hippocampus. In the liver, exercise activates SIRT1, improving lipid catabolism, reducing fat accumulation, mitigating insulin resistance, and curbing systemic inflammation that would otherwise accelerate cognitive decline via the liver–brain axis. Hepatic dysfunction, as seen in NAFLD, is specifically identified as a driver of brain energy deficits and neuroinflammation.
In the aging brain itself, exercise suppresses microglial and astrocyte-driven neuroinflammation via NF-κB inhibition, elevates BDNF to sustain hippocampal neurogenesis, and enhances autophagy-mediated clearance of toxic protein aggregates (amyloid-beta in AD; alpha-synuclein in PD). These effects are amplified by epigenetic reprogramming, including Nrf2-driven antioxidant gene expression and circadian rhythm synchronization, which collectively create a more resilient neuroimmunometabolic environment. The review also highlights IL-6's hormetic duality: acutely pro-regenerative when released by muscle during exercise, yet chronically inflammatory when produced by adipose tissue in sedentary aging.
The authors acknowledge important limitations. As a narrative review, it cannot establish causation between exercise and observed outcomes; confounders including genetics, diet, sleep, and baseline health complicate interpretation. Optimal exercise modalities, intensities, and durations for specific aging phenotypes remain undefined, and translational gaps between animal models and human clinical outcomes persist. The authors call for precision medicine approaches integrating omics technologies, circadian biology, and combination therapies to operationalize these findings.
Key Findings
- Exercise activates AMPK/PGC-1α in muscle, boosting mitochondrial biogenesis and restoring glucose and fatty acid metabolism.
- Muscle-derived myokines BDNF and IL-6 cross into the brain to promote neurogenesis, synaptic plasticity, and neuroprotection.
- Hepatic SIRT1 activation by exercise reduces insulin resistance, lipid accumulation, and systemic inflammation protecting brain energy supply.
- Exercise suppresses NF-κB neuroinflammation and enhances autophagy to clear Alzheimer's amyloid-beta and Parkinson's alpha-synuclein aggregates.
- Epigenetic mechanisms including Nrf2 antioxidant signaling and circadian synchronization amplify exercise's multi-organ anti-aging effects.
Methodology
This is a narrative review synthesizing peer-reviewed literature from PubMed, Scopus, Web of Science, and Google Scholar (2000–2024). Study types included RCTs, cohort studies, animal models, and meta-analyses. Evidence quality was graded using a modified GRADE framework prioritizing controlled trials and large-sample studies.
Study Limitations
As a narrative review, this paper cannot establish causality between exercise and anti-aging outcomes; selection bias in included studies is possible. Key confounders—genetics, diet, sleep quality, and baseline organ health—are acknowledged but not systematically controlled across the synthesized literature. Optimal exercise type, dose, and timing for specific aging or neurodegenerative phenotypes remain unresolved and require prospective RCTs.
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