A practical Broth & Co guide to muscle signalling, myokines, glucose metabolism, brain health, gut health, protein and movement across life.

Muscle Is More Than Movement

For a long time, muscle was mostly discussed as the tissue that helps us move. Muscles help us walk, lift, climb stairs, maintain posture, play sport, carry children, garden, dance, work and live independently.

That is still true, but it is no longer the whole story. Skeletal muscle is also a metabolically active signalling organ. When it contracts during physical activity, it can communicate with other tissues through a wide range of signalling molecules.

This changes the way we think about movement. Exercise is not only about burning calories, changing body shape or building visible muscle. Every contraction is also part of a biological conversation.

That matters across life: children and teens need movement for growth, coordination and confidence; adults need muscle for energy, strength and metabolic health; new mums may need gentle rebuilding after pregnancy and birth; active people need recovery; and older adults need muscle for mobility, independence and physical reserve.

Quick Answer: Why Is Muscle Called an Endocrine Organ?

Skeletal muscle is sometimes described as an endocrine organ because active muscle can produce and release signalling molecules that influence biological processes locally and in other parts of the body.

Many of these muscle-derived signalling molecules are called myokines. They can participate in communication between muscle and tissues such as the brain, liver, adipose tissue, bone, immune system and gastrointestinal system.

This does not mean muscle works exactly like the thyroid, pancreas or other traditional endocrine glands. It means muscle is not passive. It participates in whole-body signalling.

What Are Myokines?

Myokines are signalling molecules produced and released by skeletal muscle, especially in response to muscle contraction and exercise. Researchers have identified many muscle-derived factors with potential roles in metabolism, inflammation, tissue communication, energy regulation and adaptation to exercise.

 

Myokine biology is complex. The effect of a molecule can depend on where it is produced, when it is released, how long it stays elevated and the broader health context.

Movement Is a Biological Signal

When skeletal muscle contracts, several things happen at once. Muscle uses ATP, increases energy demand, changes glucose uptake, alters local blood flow, responds to mechanical load, interacts with mitochondria and can release signalling molecules.

A walk, strength session, cycle, swim, dance class or active day is therefore more than an event that uses energy. It is a stimulus. Repeated over time, that stimulus helps the body adapt.

The phrase is simple, but powerful: movement is information. Muscle contraction is a signal. Adaptation is the body's response.

For the muscle and cellular energy connection, see The Muscle–Mitochondria Connection: How Muscle Supports Energy, Metabolism & Healthy Ageing and Mitochondrial Health: The Missing Link Between Energy, Ageing, Metabolism & Recovery.

Why Muscle Matters for Metabolic Health

Skeletal muscle is one of the body's major sites for glucose uptake and glycogen storage. After carbohydrate-containing foods are digested, glucose enters the bloodstream. Insulin helps coordinate glucose uptake and storage, and skeletal muscle plays a major role in this process.

Contracting muscle can also increase glucose uptake through pathways that are not identical to insulin signalling. This is one reason a short walk after meals, regular movement and resistance exercise can be valuable parts of a metabolic health routine.

The key message is not that one myokine fixes blood sugar. The more accurate message is that active skeletal muscle participates in mechanical, metabolic and signalling responses that influence whole-body glucose regulation.

For more context, read Muscle, Metabolism & Lifelong Health: Why Muscle Matters at Every Age and How to Build a Leaner, Stronger Body: Muscle, Metabolism & Nutrition Through Every Life Stage.

Myokines, Inflammation and Context

Inflammation is often spoken about as though it is always harmful. It is not. Inflammation is a normal biological process involved in immune defence, tissue repair and adaptation.

The concern is persistent dysregulated inflammation. Exercise adds an important nuance: muscle contraction can produce temporary changes in cytokines and other signalling molecules, and those short-term exercise signals occur in a very different context from long-running inflammatory states.

IL-6 is a good example. IL-6 can be discussed in inflammatory contexts, but muscle-derived IL-6 during exercise is not the same as persistent elevation in chronic inflammatory states. Source, timing, concentration and duration all matter.

This is why wellness language needs care without sounding fearful. Molecules are rarely simply good or bad. Healthy physiology depends on regulation, timing and balance. Chronic Inflammation Explained: Diet, Lifestyle, Gut Health & Everyday Wellbeing explains this broader topic.

Muscle and the Brain

One of the most interesting areas of research is muscle-brain communication. Physical activity is associated with effects on mood, sleep, stress regulation, cerebral blood flow, cognition and neuroplasticity-related pathways.

The mechanisms are complex and likely involve circulation, metabolic health, nervous system signalling, immune pathways, muscle-derived factors and neurotrophic pathways such as BDNF biology.

This does not mean one myokine controls mental health or memory. It means movement influences the body as a connected system, and the brain is part of that system. The gut also belongs in this conversation, which is why The Gut-Brain Axis Explained is a useful companion article.

Muscle, Mitochondria and Energy

Muscle contraction requires energy. Mitochondria help produce ATP, especially during aerobic activity and sustained movement. Exercise creates changing energy demands, and those demands activate signalling pathways.

Over time, repeated physical activity can support adaptations in mitochondrial capacity, oxidative metabolism, glucose handling, physical fitness and muscle function. This creates a broader sequence: muscle contraction, energy demand, cellular signalling, metabolic response and adaptation.

This matters for children who need active play, adults who feel tired and sedentary, new mums rebuilding capacity, athletes seeking performance, and older adults preserving energy and mobility.

The Gut-Muscle Axis

The gut is another part of the muscle network. Researchers are increasingly studying the gut-muscle axis: relationships between the gut microbiome, microbial metabolites, nutrient absorption, immune signalling, physical activity and muscle function.

The gut microbiome can produce metabolites such as short-chain fatty acids from the fermentation of certain fibres. These metabolites are being studied for roles in gut barrier function, immune pathways and metabolic signalling.

The research is still developing, but the practical foundations are familiar: eat enough protein, include fibre-rich plants, support digestive wellbeing, move regularly and recover well. Read The Gut-Muscle Axis for the deeper article.

Why Protein Matters for an Active Signalling Organ

If skeletal muscle is active tissue, maintaining it requires appropriate nutrition. Dietary protein provides amino acids needed for muscle protein synthesis, tissue maintenance, enzymes, transport proteins, immune proteins and many other biological functions.

Complete protein foods include eggs, fish, seafood, meat, poultry, dairy foods, soy foods and appropriate combinations of plant proteins. Needs vary with age, body size, activity, training, pregnancy and postpartum recovery, appetite and health status.

The practical message is simple: do not wait until dinner to think about protein. Include meaningful protein sources across the day. High-Protein Foods: The Foundation of Muscle, Healthy Ageing & Recovery Nutrition, Protein Quality vs Quantity: Why Both Matter for Health & Healthy Ageing, Protein Throughout Life: Why Your Protein Needs Change With Age and Protein Timing for Health, Performance & Recovery explain this in more detail.

Where Collagen and Bone Broth Fit

Collagen is a protein, but it has a different amino acid profile from complete proteins. It is rich in glycine, proline and hydroxyproline, amino acids commonly associated with connective tissues.

That distinction matters. Collagen should complement, not replace, complete protein foods for muscle maintenance. But movement depends on more than muscle fibres alone. Tendons, ligaments, fascia, connective tissue and the extracellular matrix are also part of the physical system that helps you move.

For this reason, many people use collagen-rich foods alongside a broader protein strategy. Collagen Amino Acids Explained: Glycine, Proline & Hydroxyproline, Amino Acids vs Peptides vs Protein vs Collagen Peptides and Bone Broth vs Collagen vs Protein explain the differences.

Broth & Co Bone Broth can contribute naturally occurring protein, collagen-derived amino acids, fluid, savoury flavour and meal versatility as part of a balanced diet. It is not a myokine supplement and it does not replace exercise, but it can fit into soups, stews, sauces, savoury drinks, post-activity meals and everyday cooking.

For product and research context, see Bone Broth Benefits: The Complete Guide to Gut Health, Protein, Recovery & Healthy Ageing, Bone Broth Clinical Study: Digestive Wellbeing & Intestinal Permeability Research | Broth & Co and Bone Broth, Collagen & Functional Nutrition.

Do You Need a Gym?

No. Muscle contraction happens during many forms of movement: walking, climbing stairs, carrying groceries, gardening, swimming, cycling, dancing, bodyweight exercise, resistance bands and weight training.

Different forms of movement create different signals. Walking is valuable, but it does not create the same progressive resistance stimulus as strength training. Aerobic activity strongly challenges cardiorespiratory capacity and mitochondrial systems. Resistance training strongly challenges force production, muscle strength and neuromuscular function.

For most people, the better question is not cardio or strength. It is how to combine movement patterns that support both metabolic capacity and physical strength.

Women, Men and Muscle Across Life

For women, the concept of muscle as a signalling organ is relevant across puberty, pregnancy, postpartum recovery, perimenopause, menopause and later adulthood. These stages can influence body composition, bone health, insulin sensitivity, recovery and physical function.

For men, muscle matters across adulthood as work, family life and lifestyle often become more sedentary. Strength, visceral fat, physical capacity and metabolic health can change gradually over time.

The exact strategy should suit the person, but the foundations are familiar: enough protein, progressive resistance, regular movement, sleep, recovery and nutrient-dense meals. For more targeted guidance, read Women, Muscle & Metabolism: How to Build Strength, Improve Body Composition & Support Healthy Ageing and Men, Muscle & Metabolism: How to Build Strength, Improve Body Composition & Support Healthy Ageing.

A Simple Framework for Active Muscle

 

For practical meals, browse our collection of nourishing recipes, including Mediterranean Bone Broth Recipes, From Australia to Asia: A Journey Through Traditional Soups, Broths & Nourishing Recipes, Healing Soups & Nourishing Broths: Bone Broth Recipes for Recovery, Vegetable-Forward Nourishing Soups and 7-Day Bone Broth Meal Plan: Gut Health, Energy & Easy Daily Nutrition.

Frequently Asked Questions

What does it mean that muscle is an endocrine organ?

It means skeletal muscle can produce and release signalling molecules that influence biological processes locally and elsewhere in the body, especially during muscle contraction and exercise.

What are myokines?

Myokines are signalling molecules produced and released by skeletal muscle. They are part of an active research field exploring communication between muscle and other tissues.

When are myokines released?

Many myokines are associated with muscle contraction and exercise, although the pattern depends on the specific molecule, exercise type, intensity, duration and individual context.

Is IL-6 always inflammatory?

No. IL-6 biology is context-dependent. Acute muscle-derived IL-6 during exercise occurs in a different physiological context from persistent elevation associated with some chronic inflammatory states.

How does muscle affect blood sugar?

Skeletal muscle is a major site of glucose uptake and glycogen storage. Muscle contraction can also increase glucose uptake through pathways that are not identical to insulin signalling.

Can walking support muscle signalling?

Walking involves repeated skeletal muscle contraction and can contribute to exercise-related signalling. Strength training remains important for building and preserving muscle strength.

Does protein increase myokines?

Protein supports muscle maintenance and adaptation, but eating protein is not the same as the contraction-driven signalling environment created by movement. Nutrition and exercise work together.

Is collagen good for muscle?

Collagen provides amino acids associated with connective tissue, but it should complement rather than replace complete protein foods for muscle maintenance.

Where does bone broth fit?

Bone broth can contribute naturally occurring protein, collagen-derived amino acids, fluid and savoury flavour as part of a balanced diet. It works best alongside complete protein foods and regular movement.

Summary

Muscle is not simply mechanical tissue. It moves the body, stores glucose, uses energy, interacts with mitochondria, supports physical capacity and participates in whole-body signalling.

The discovery of myokines gives us a richer way to understand movement. Every contraction is part of a biological conversation. The practical foundations remain beautifully simple: move regularly, challenge muscle appropriately, eat enough protein, support gut and cellular energy, recover well and keep going across life.