Did you know that when you move, your muscles release the so-called 'hope molecules,' or myokines, that may have anti-depressant effects? The feel-good sensations are often credited to endorphins, but these molecules are different. We talked to Dr. Rammohan Rao, Principal Research Scientist at Apollo Health, to explain how.
What are myokines?
Dr. Rao explained that myokines are a class of cytokines and growth factors released by the skeletal muscle cells that link muscles, movement, moods, emotions, and the brain. In other words, they are a part of the body's intricate communication network interacting with various organs. Myokine effect extends to cognition, lipid and glucose metabolism, bone formation, and even skin tone.
The scientist noted that "They are able to cross the blood-brain barrier and impact brain function.” He also added that these chemicals may potentially increase resiliency to mental stress, reduce symptoms of depression and trauma, and help individuals recover from stress due to anti-depressant effects on the brain.
So far, nearly 650 molecules have been identified as belonging to the class of myokines, suggesting that multiple pathways that regulate mood and emotions may be targeted by myokines.
Some myokines, including Interleukin 6 and irisin, have been associated with health benefits such as improved metabolism and potential effects on brown-fat formation. Additionally, factors like IGF-1 and brain-derived neurotrophic factor (BDNF) have been linked to increased brain cell growth.
How 'hope molecules' can help improve mood
The concept of 'hope molecules' brings a new perspective to the relationship between physical activity and mental health. It's yet another science-driven proof validating the intricate connection between our body and mind, and a powerful reminder of the impact of movement on our overall well-being.
Dr. Rammohan Rao said that while research is ongoing and it's not exactly clear how these 'hope molecules' act as anti-depressants, exercise and movement trigger their release. These molecules have pleiotropic effects — a phenomenon where a single gene or genetic variant influences multiple, seemingly unrelated biological processes.
When we asked Dr. Rao how long the beneficial effects last, he said it’s not clear just yet. “However, the benefits are sustained as long as the triggers are active," he added.
Whether it's a brisk walk in the park, a vigorous high-intensity interval training, or a restorative yoga session, every bit of movement counts and unleashes a cascade of molecules that may help improve your mood and resilience.
The link between exercise and mental health
The connection between exercise and mood improvement is not new, but the discovery of 'hope molecules' adds an interesting layer. Dr. Rao underscored that “Research suggests that for mild-moderate depression, physical activity can be as effective as anti-depressants or psychological treatments like cognitive behavioral therapy.”
According to a recent systematic review of 97 studies published in the British Journal of Sports Medicine, symptoms of depression, anxiety, and distress have improved with physical activity across the general population, people with diagnosed mental health disorders, and people with chronic disease.
Dr. Rao noted that “Thanks to the positive effects of myokines on mental health, more and more practitioners are recommending exercise for treating depression and depressive symptoms.”
Myokines and the brain
One study investigating the muscle–organ crosstalk via myokines noted that exercise may influence the hippocampus more than any other part of the brain. Why is that relevant?
The hippocampus, a seahorse-shaped brain region, is essential to memory formation, spatial navigation, learning, and emotion regulation. As we age or because of health conditions, its volume can decrease, which is often seen in Alzheimer’s disease research using brain imaging techniques.
Studies have found that there’s a connection between smaller hippocampal volumes and major depressive disorder. However, more research is needed to uncover which one occurs first and which influences the other. Additionally, one study published in Biological Psychiatry reported how there’s a key 'hope molecule' at play here — BDNF.
Underscoring those findings, researchers have also seen how exercise would increase hippocampal volume and blood flow to the brain and was also associated with higher serum levels of BDNF.
In other words, the more physically active you are, the higher levels of BDNF you’ll have, which may help protect your brain and hippocampal volume.
'Hope molecules,' scientifically known as myokines, are a class of cytokines and growth factors released by the skeletal muscle cells that link muscles, movement, moods, emotions, and the brain.
More than 650 molecules have been identified as belonging to the class of myokines thus far.
Exercise influences the hippocampus more than any other part of the brain.
BDNF, or brain-derived neurotrophic factor, is key to increasing hippocampal volume and improving cognitive health.
- Current Osteoporosis Reports. Muscle, bone, and fat crosstalk: the biological role of myokines, osteokines, and adipokines.
- British Journal of Sports Medicine. Effectiveness of physical activity interventions for improving depression, anxiety and distress: an overview of systematic reviews.
- Endocrine Reviews. Muscle–organ crosstalk: the emerging roles of myokines.
- Biological Psychiatry. Depression and the hippocampus: cause or effect?
- NeuroImage: Clinical Hippocampal volume across age: nomograms derived from over 19,700 people in UK Biobank.
- Biological Psychiatry. A neurotrophic model for stress-related mood disorders.
- Brain Plasticity. The effects of acute exercise on mood, cognition, neurophysiology, and neurochemical pathways: a review.