It has long been known: people who move regularly live longer and healthier lives on average. For a long time, however, it was unclear why movement is so powerful – beyond better fitness, muscle strength or endurance.
In 2007 it became clear that, during exercise, the muscle produces substances that are released into the bloodstream and influence other organs. These substances are called myokines. Today they are regarded as a possible key to understanding why movement can work like a kind of natural medicine.
What are myokines?
Myokines are hormone-like messengers released by actively working muscle. A messenger is a substance that helps the body transmit information from one place to another. In this way, myokines act not only in the muscle itself, but also on distant organs such as the brain, liver, fat tissue, bones or the immune system.
This turns the muscle, during exercise, into an endocrine organ. An endocrine organ is an organ that releases substances (e.g. hormones) into the bloodstream in order to influence other tissues. In contrast, exocrine organs release their substances to external or internal surfaces, such as the salivary or sweat glands. Examples of endocrine organs are the thyroid or the pancreas.
The difference from other endocrine organs: The muscle only produces its messengers when it is used, i.e. activated.
Today it is assumed that there are more than 200 different myokines. Many have not yet been fully researched. It is known, however, that myokines influence central processes in the body, including:
- Inflammation (reducing unnecessary inflammatory processes)
- Metabolism (how the body provides energy)
- Glucose uptake (bringing sugar into the cells)
- Insulin sensitivity (how well cells respond to insulin)
- Neuroplasticity (the brain's ability to adapt)
- Fat burning
- Immune system
- Muscle building
- Bone metabolism
This explains why inactivity promotes so many health problems – and why movement can compensate for them again.
Examples of well-known myokines and their effects
Interleukin-6 (IL-6)
IL-6 was the first myokine detected in the blood after exercise. IL-6 has an anti-inflammatory effect (it reduces unnecessary inflammation), supports the uptake of glucose into the muscle and improves insulin sensitivity (cells respond better to insulin).
With more intense muscle work, IL-6 release rises more strongly. This is one reason why it is not just “any movement” that matters, but also intensity that plays a role in training.
Brain-Derived Neurotrophic Factor (BDNF)
BDNF is a growth factor produced in the brain and in the muscle. A growth factor is a substance that helps cells to grow, change or build new connections.
BDNF supports:
- learning & memory
- neuroplasticity (the brain can form new synaptic connections)
- mood & stress processing
BDNF thus explains why movement can improve cognitive abilities and alleviate depressive symptoms; both in the short and long term. Here movement acts neurobiologically – that is, directly via the nervous system.
Insulin-like Growth Factor 1 (IGF-1)
IGF-1 is a peptide hormone. A peptide hormone is a hormone made up of amino acids. IGF-1 promotes muscle protein synthesis (the building of new muscle proteins) and at the same time inhibits protein breakdown. This is crucial for maintaining muscle mass and relevant in conditions such as sarcopenia (age-related muscle loss).
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Why are myokines considered a possible turning point?
Myokines show that movement has not only mechanical but also biochemical effects. They help explain why training has an influence on all organ systems and structures of the human body, thus changing the picture of the musculature:
The muscle is not just a locomotor apparatus, but a health organ.
Relevance for prevention & therapy
For prevention this means:
Movement is a health intervention – not just a hobby.
For therapy it likewise means:
Inactivity creates a biochemical deficiency.
This is particularly relevant in the case of:
- type 2 diabetes
- metabolic syndrome
- cardiovascular diseases
- depression
- dementia
- chronic inflammation
- sarcopenia
- cancer
In many areas, new therapeutic approaches are emerging today that no longer regard movement as a lifestyle recommendation, but as a medical stimulus.
Which forms of training particularly stimulate myokines?
For myokines to be released, light everyday movement is often not enough. The musculature must be actively challenged. From research and practice, several stimulus principles can be derived that are particularly effective:
- High muscular exhaustion The more strongly a muscle is worked, the more myokines are released. “Exhaustion” here means that a muscle could not continue indefinitely, but reaches its limits. This stimulus strengthens, among other things, IL-6, which has an anti-inflammatory effect and improves sugar metabolism.
- Neuromuscular activation Complex or coordinatively demanding movements challenge the interplay between the nervous system and the musculature. This stimulates factors such as BDNF, which support the brain and influence learning and mood processes.
- Mechanical tension Mechanical tension arises when a muscle has to produce force against a resistance – e.g. during strength training. This stimulus stimulates IGF-1, which supports muscle building by promoting protein synthesis and inhibiting protein breakdown.
- Large muscle groups and full-body training The more muscle mass is involved, the greater the myokine potential. A full-body workout activates far more musculature than isolated, very small movements.
- Combination of strength and endurance Combined stimuli appear to act synergistically: endurance improves metabolic and brain processes, strength maintains or builds muscle mass. Together this creates a larger window of effect.
These stimulus patterns are found particularly in forms of training such as:
- strength training (classic or functional)
- interval and sprint training (high intensity, short breaks)
- metabolic workouts (strong full-body load)
- outdoor sports (additional sensory stimulation)
- combined training methods (e.g. circuit models)
Another point:
More muscles = more production capacity for myokines.
This means: anyone who regularly integrates strength training increases the body's ability to produce myokines at all.
Put differently: the more intense, varied and muscle-activating a training session is, the more strongly the muscle is activated as an “endocrine organ”.
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Points that, despite progress, could be examined more closely
Despite the progress, open questions remain – among them:
- Individualisation It is unclear how strongly genetics, age, sex, metabolic variants and pre-existing conditions influence how many myokines a person produces. It may be that people benefit to different degrees.
- Dosage & timing It has not yet been sufficiently clarified how often, how intensely and at what intervals one should train in order to achieve optimal myokine effects. Concrete guidelines are lacking here.
Practical significance – for everyday life and training
For everyday life the following applies:
More movement = more myokines More muscle mass = more production capacity
For trainers this means:
- Muscle training becomes a preventive measure
- Lack of movement is a risk factor
- Training influences the brain, metabolism and immune system
- Muscle work has an inflammation-regulating effect
Conclusion: the muscle as a health-active organ
Myokines change our understanding of training. Movement is not only mechanical, but also endocrinologically, neurologically and immunologically effective.
Or, put more simply:
Without muscle no myokines – and without myokines less health.
