Cross-Organ Muscle Communication: A Study on the Systemic Effects of Myokines on Adipose Tissue, Bone, and the Brain

Foreword: A Scientific Bridge from the Laboratory to Taiwan’s Roads

When you exercise, your muscles are not fighting alone—they act like a command center, sending signals to organs throughout the body and coordinating systemic adaptation. This “muscle-organ crosstalk” operates through myokines, linking fat, bone, brain, and liver into a metabolic network. Understanding it means understanding why “people with more muscle are healthier.” This article delves into this muscle-dominated communication network.

Muscle–Fat Crosstalk

Irisin secreted by muscle promotes “browning” of white adipose tissue (forming beige-like fat), increasing thermogenesis and energy expenditure; IL-6, IL-15, and others also regulate fat metabolism and lipolysis. This muscle–fat axis means exercise does not merely burn energy within muscle but also “directs” adipose tissue to raise metabolic activity, helping combat obesity and improve metabolism. In those with adequate muscle mass, this beneficial fat regulation is more active—this is the endocrine contribution of muscle to body-fat management.

Muscle–Bone Crosstalk

Muscle and bone are not only mechanically linked but also communicate biochemically. Myokines (such as IGF-1 and irisin) influence bone metabolism, while osteocalcin secreted by bone in turn affects muscle function and energy metabolism, forming a bidirectional “muscle–bone unit.” The mechanical load of exercise, together with these signals, maintains bone density and muscle strength. This explains why weight-bearing exercise simultaneously strengthens muscle and bone, countering sarcopenia and osteoporosis—the pair of aging-related problems that often occur together.

Muscle–Brain Crosstalk

Myokines also affect the brain: exercise-induced irisin may promote BDNF expression in the brain and support neuroplasticity; IL-6, cathepsin B, and others are also being studied for their association with cognitive benefits. This muscle–brain axis is part of the mechanism by which exercise protects the brain—muscle contraction signals travel through the blood to influence neurogenesis and plasticity in the brain. Maintaining muscle activity is therefore not only for the body but also for brain health; muscle can be regarded as a “thinking organ partner.”

The Bidirectional Bone–Muscle Dialogue: The Surprise of Osteocalcin

Muscle and bone are not only mechanically linked but also engage in bidirectional endocrine dialogue. Beyond muscle secreting hormones that affect bone, bone also “talks back”—osteocalcin secreted by bone cells has been found to act on muscle, influencing muscle energy metabolism and adaptation during exercise, and even affecting systemic glucose metabolism and male reproductive function. Karsenty and Olson (2016, Cell) described this unexpected paradigm of the “bone–muscle endocrine axis.” During exercise, the mechanical load of muscle contraction and the endocrine signal of osteocalcin jointly maintain bone density and muscle strength. This bidirectional dialogue shows that weight-bearing exercise strengthening both muscle and bone is no coincidence, but the result of these two tissues coordinating closely at the endocrine level, countering sarcopenia and osteoporosis—the pair of aging-related problems that often occur together.

The Muscle–Brain Axis: An Endocrine Pathway for Exercise’s Brain Protection

One fascinating axis of muscle inter-organ communication is the “muscle–brain axis.” Signal molecules secreted by muscle during exercise (such as irisin, cathepsin B, and mediators affecting BDNF) can influence neurogenesis, plasticity, and cognition in the brain. Pedersen (2019, Nature Reviews Endocrinology) reviewed the role of muscle–brain crosstalk in the cognitive benefits of exercise. This axis provides an endocrine explanation for “how exercise benefits the brain from the muscle”—not merely the general effects of blood flow and trophic factors, but precise signals actively secreted by muscle and acting remotely on the brain. This deepens the scientific basis for “moving the body is also moving the mind”: maintaining muscle activity and mass is not only for physical performance but also supports cognitive and emotional health through the muscle–brain axis, with particular significance for cognitive care in older age.

An Integrated View of Inter-Organ Communication Research

Research on muscle inter-organ communication represents a shift in exercise physiology from a “local” to a “systemic” integrated perspective. Past research often focused on a single tissue (e.g., how muscle becomes stronger), whereas inter-organ communication reveals that exercise is a coordinated dialogue among organs throughout the body—muscle, fat, bone, brain, liver, pancreas, and immune system coordinating through signals such as myokines. This integrated view explains why the benefits of exercise are so broad and systemic (from metabolism to cognition to bone), and why “maintaining muscle mass” means far more than strength alone. The challenges of this research lie in the extreme complexity of the communication network, the still-unclear functions of individual signal molecules (such as the controversy over irisin), and the difficulty of fully validating causal relationships between organs in humans. Nevertheless, the integrated paradigm has gained broad support. The takeaway for readers is that exercise is a whole-body health investment, and muscle—as the core voice of this network—deserves proper maintenance through resistance training and adequate protein to sustain the endocrine communication that protects the entire body.

Interdisciplinary Perspectives: Muscle as the Hub of Whole-Body Health

Research on muscle inter-organ communication integrates endocrinology, metabolic science, and exercise physiology, establishing muscle’s status as the “hub of whole-body health.” Through myokines, muscle converses with fat, bone, brain, liver, and pancreas, coordinating whole-body metabolism—a discovery that elevates the systemic nature of exercise benefits to the level of molecular networks. The revolutionary aspect of this interdisciplinary integration lies in revealing the profound significance of “maintaining muscle mass”: not only for strength, but for sustaining an endocrine communication network that protects the entire body. From the muscle–fat perspective, irisin promotes fat browning; from the muscle–bone perspective, bidirectional endocrine dialogue maintains bone density and muscle strength; from the muscle–brain perspective, myokines support neuroplasticity; from the muscle–metabolic perspective, insulin sensitivity improves. This perspective elevates exercise physiology from the “local” (how muscle becomes stronger) to the “systemic” (how muscle coordinates the whole body), explaining why the benefits of exercise extend across metabolism, bone, cognition, and cardiovascular health. It provides a unified framework for combating sarcopenia, metabolic syndrome, osteoporosis, and cognitive decline. Understanding muscle’s hub status lets us recognize that “building muscle” is the switch that activates the body’s health network, with resistance training and adequate protein as the core of maintaining this system.

From Research to the Training Ground: An Action Framework for Maintaining the Muscle Hub

Maintaining muscle as the hub of whole-body health can follow the framework of “maintain muscle mass—weight-bearing exercise—combine aerobic and resistance—adequate protein.” Maintain muscle mass: muscle mass is a metabolic and endocrine asset; adequate muscle mass means more active myokine secretion, protecting fat, bone, brain, and metabolism; combating sarcopenia (especially in middle-aged and older adults) is key to maintaining this network. Weight-bearing exercise: weight-bearing and resistance exercise simultaneously strengthen muscle and bone (the bidirectional muscle–bone endocrine dialogue), tackling sarcopenia and osteoporosis—the pair of aging-related problems that often occur together—in one stroke. Combine aerobic and resistance: aerobic exercise induces IL-6, irisin, and others, while resistance training maintains muscle mass and stimulates synthesis; different exercises induce different myokines, and the combination yields the most comprehensive benefits. Adequate protein: provides the raw materials for muscle maintenance and synthesis (approximately 1.6–2.2 g per kg, distributed across meals). For the prevention and management of metabolic syndrome, diabetes, and sarcopenia in Taiwan, resistance training is a critical gap often overlooked by many—especially older adults and women. The core of this framework is: by maintaining muscle mass, engaging in weight-bearing and resistance exercise, combining aerobic work, and consuming adequate protein, we maintain muscle as the endocrine hub that coordinates and protects the whole body (fat, bone, brain, metabolism)—an essential component of preventive medicine for the entire population, particularly middle-aged and older adults.

Local Application in Taiwan: Climate, Events, and Cultural Context

As Taiwan’s population ages, sarcopenia and its associated osteoporosis and metabolic decline are major health threats. Research on muscle inter-organ communication provides a powerful argument: maintaining muscle mass is not only about strength, but about sustaining a whole-body endocrine network that protects fat, bone, and brain. This encourages everyone—especially middle-aged and older adults—to prioritize resistance training and protein intake to maintain muscle. Taiwanese older adults often neglect strength training, and this is a critical gap in preventing sarcopenia. Combining aerobic exercise (such as cycling) with resistance training and consuming adequate protein is the core strategy for maintaining this muscle-led health network.

As Taiwan’s population ages, sarcopenia and its associated osteoporosis, metabolic and cognitive decline are major threats. Research on muscle inter-organ communication emphasizes that maintaining muscle mass is about sustaining a whole-body endocrine network that protects fat, bone, and brain. This encourages everyone—especially middle-aged and older adults—to prioritize resistance training and protein intake. Combining aerobic exercise (cycling) with resistance training is the core strategy for maintaining this muscle-led health network.

Frequently Asked Questions and Myth Clarification

Myth 1: Building muscle is only for strength and appearance? Muscle is an endocrine organ that secretes signal molecules protecting fat, bone, brain, and metabolism. Maintaining muscle mass is about sustaining a whole-body health network.

Myth 2: Older adults don’t need to build muscle? Quite the opposite. Maintaining muscle mass in middle-aged and older adults combats sarcopenia, osteoporosis, and metabolic and cognitive decline—it is the key to this inter-organ protective network.

Myth 3: Aerobic exercise is enough to maintain muscle? Aerobic exercise has many benefits, but maintaining muscle mass requires the stimulus of resistance training. Combining aerobic and resistance work, along with adequate protein, is optimal.

How to Read Exercise Science Research: Developing Evidence Literacy

This article cites four studies from leading international journals (such as the Journal of Applied Physiology, Medicine & Science in Sports & Exercise, Sports Medicine, Nature, and Cell series), but as a reader, cultivating “evidence literacy” helps you absorb this knowledge more rationally rather than accepting it wholesale. First, distinguish study types: randomized controlled trials (RCTs) have the strongest causal inference, observational studies (cohort, cross-sectional) can only show association rather than causation, and animal and cell studies reveal mechanisms but require caution when translating to humans. Second, pay attention to samples and contexts: results from small samples or specific populations (such as elite athletes or particular age groups) may not apply to you; studies predominantly based on European and American populations also warrant consideration regarding applicability to Taiwanese populations. Third, value effect size rather than looking only at “statistical significance”: statistical significance does not equal a practically large enough benefit; you must ask, “Is this difference meaningful in real training or health terms?” Fourth, be wary of over-extrapolation and commercialization: preliminary findings from a single study are often exaggerated into “miracle” products or methods; wait for replication and systematic reviews. Fifth, judge based on the “consistency” of mechanistic, associational, and interventional evidence, rather than rejecting everything because of flaws in a single study or accepting everything because of one impressive result. Sixth, understand that “individual variability” is the norm in exercise science: the same intervention produces different responses in different people due to genetics, training background, lifestyle, and environment; research presents group averages, so when applying to yourself, observe your own actual responses and adjust accordingly. Seventh, put the “fundamentals” first: sleep, nutrition, consistent training, and recovery—supported by abundant evidence with clear benefits—always deserve priority over various novel supplements, gadgets, or methods; many seemingly sophisticated interventions yield marginal benefits far smaller than getting the basics right. Exercise science is an ever-evolving field; maintaining an open yet critical attitude, updating your knowledge as evidence evolves, respecting individual variability, and valuing the fundamentals will allow you to truly translate cutting-edge research from international journals into training and health decisions that are useful, safe, and sustainable for you—rather than blindly following trends or deferring to a single authority.

Key Takeaways

Synthesizing the interdisciplinary research and mechanistic analyses above, the core points can be distilled as follows: Muscle is the command center of whole-body health: coordinating fat, bone, and brain through myokines. Maintaining muscle mass matters greatly: not only for strength, but for sustaining the endocrine network that protects the whole body. Weight-bearing exercise delivers multiple benefits at once: simultaneously strengthening muscle and bone, combating sarcopenia and osteoporosis. Middle-aged and older adults should prioritize resistance training: this is a critical gap often overlooked by Taiwanese older adults. Aerobic + resistance + protein: the core combination for maintaining muscle inter-organ communication. Behind these points lies the convergence of multiple fields—sleep science, immunology, genomics, neuroscience, microbiology, endocrinology, and data science—which together convey a core message: the benefits and adaptations of exercise are the integrated result of multiple body systems working in coordination, not something captured by any single factor. Understanding this interdisciplinary perspective helps us move beyond fragmented “treat-the-symptom” thinking and approach training, recovery, and health more holistically. Integrating these principles into daily training and life, and dynamically adjusting based on individual conditions, actual responses, and professional advice, is how we translate cutting-edge findings from top international journals into practices that are truly feasible, safe, and sustainable within Taiwan’s climate, events, and lifestyle context. The value of exercise science ultimately lies in helping every athlete—elite or amateur, young or old—enjoy sport more intelligently, healthily, and joyfully, and achieve physical and mental growth through it.

Practical Recommendations for Taiwanese Athletes

1. Muscle is the command center of whole-body health: coordinating fat, bone, and brain through myokines.
2. Maintaining muscle mass matters greatly: not only for strength, but for sustaining the endocrine network that protects the whole body.
3. Weight-bearing exercise delivers multiple benefits at once: simultaneously strengthening muscle and bone, combating sarcopenia and osteoporosis.
4. Middle-aged and older adults should prioritize resistance training: this is a critical gap often overlooked by Taiwanese older adults.
5. Aerobic + resistance + protein: the core combination for maintaining muscle inter-organ communication.

References and Further Reading

• Severinsen, M. C. K., & Pedersen, B. K. (2020). Muscle-organ crosstalk: the emerging roles of myokines. Endocrine Reviews, 41(4), 594–609.
• Boström, P., et al. (2012). A PGC1-α-dependent myokine (irisin) drives brown-fat-like development of white fat. Nature, 481, 463–468.
• Karsenty, G., & Olson, E. N. (2016). Bone and muscle endocrine functions: unexpected paradigms of inter-organ communication. Cell, 164(6), 1248–1256.
• Pedersen, B. K. (2019). Physical activity and muscle-brain crosstalk. Nature Reviews Endocrinology, 15(7), 383–392.

This article is a translation of exercise science knowledge. Individual physiological responses vary; please consult professional coaches and sports medicine physicians before making any training or intervention changes, and proceed gradually according to your personal health status.

Related Reading

• The Secretory Function of Skeletal Muscle: Research on the Systemic Metabolic Regulation of Myokines
• The Dual Role of Inflammatory Signals in Training Adaptation: Research on the Acute vs. Chronic Benefits of IL-6
• Cycling and Weight Management: Fat-Burning Benefits of Aerobic Exercise and Dietary Integration Strategies
• The Impact of Muscle Coordination Training on Cycling Efficiency: Research on the Neural Control of Multi-Joint Movements