Exercise is often talked about or considered a tool for fitness goals, muscles gained, calories burned or weight loss. But the reality is, movement is doing far more beneath the surface than just changing our physical appearance.

Every time we move, our body sends chemical signals throughout our brain, nervous system, muscles, gut and hormones. This is like a conversation between our body systems, and it can actually influence everything from stress, mood and metabolism, to sleep, energy and cognitive function.

Movement is one of our most powerful tools to regulate and support the entire human body. 

The type of movement might look slightly different for everyone. Whether this is a 10-15 minute brisk walk at lunchtime, a weights program at the gym, mastering a tricky yoga pose, running 10 km, or taking a spin class, it will stimulate many of the same core neurochemical pathways responsible for dopamine production, serotonin release, and stress regulation.

Below are how these ‘four chemicals’ are supporting your body with movement:

We’ve all heard of Endorphins. Sometimes known as our natural painkiller. Released within minutes of starting exercise, endorphins help to block pain signals to the brain. They create that warm, glowing feeling that makes a hard workout feel almost meditative by the end. Even a brisk 10-minute walk is enough to trigger a measurable release.

Dopamine is the chemical of reward and drive. Every time you finish a workout, your brain releases a surge of dopamine to say, "That was great, let's do it again." This doesn't just make you like exercise more but can actually spill over into your daily life, supporting your focus, productivity and more of that "ready to take on the day" feeling. 

Over time, consistent exercise helps stimulate the brain to make more dopamine and dopamine receptors. This means we create a positive feedback loop in the brain: movement rewards you with a mood-boosting high, which naturally fuels your motivation to exercise even more. 

Serotonin is your mood stabiliser. Otherwise known as your body’s natural “feel good” chemical or ”happy hormone”. When we exercise, we increase the amount of an amino acid required to produce serotonin, called tryptophan. This crosses the blood-brain barrier, where it can be converted into serotonin. 

Something that people often forget is that serotonin is actually a precursor to melatonin. When you’re producing more serotonin, you are actively producing more of the raw materials for your sleep hormone, melatonin. Meaning, your body can more efficiently convert this into melatonin at night. Exercise isn't just supporting your mood; it's literally helping manufacture your sleep hormone.

Endocannabinoids, specifically one called Anandamide, is what’s known as our bliss molecule. Your body has a built-in network called the Endocannabinoid System, and it is responsible for maintaining homeostasis (balance) in your nervous system, regulating mood, pain, appetite, and stress. Whenever something throws your body out of balance, the endocannabinoid system kicks in to help bring your body back to baseline. Exercise stimulates the body’s endocannabinoid system, and research shows that after 30–45 minutes of moderate intensity exercise, levels of anandamide increase significantly, contributing to the "runner's high" - the calm, uplifted feeling many people experience after movement. 

So what else is exercise doing for us?

Something that surprises most people is that roughly 90-95% of your body's serotonin isn't made in your brain. It's made in your gut. Your gut lining contains specialised cells called enterochromaffin cells, and these are actually responsible for producing the majority of your body's serotonin supply.

Regular movement alters the composition of your gut microbiome, helping to increase bacterial diversity and enhancing the microbial pathways that produce serotonin and other mood, sleep, and stress-regulating chemicals. While simultaneously building a more resilient gut lining and signalling your microbiome to ramp up production of butyrate, the short-chain fatty acid responsible for fuelling your cells and supporting inflammation.

Movement also naturally improves your gut motility and speeds up sluggish digestion. By keeping food and waste moving smoothly through your system, movement becomes an effective way to support common digestive issues like chronic bloating, trapped gas, and constipation.

This is why people refer to the gut as your "second brain." The two are in constant conversation, and exercise is one of the most effective ways to keep that conversation going in the right direction.

Which brings us to cortisol. Cortisol is our primary stress hormone, produced by what is called the HPA axis  (a communication loop between your hypothalamus, pituitary gland, and adrenal glands). When you're under chronic stress, this system becomes overactivated, keeping cortisol levels higher for longer periods of time. Over time, this takes a toll on mood, sleep, immune function, and cognitive performance.

While exercise is itself a physical stressor, causing a short-term spike in cortisol, it's what happens in the recovery window afterwards that matters. As your body returns to its baseline, the HPA axis actively down-regulates, producing less cortisol than it did before. This trains your stress-response system to become more efficient. In practical terms: faster recovery, and a less reactive response to everyday stressors.

What does this look like for us in day-to-day life?

On a daily basis, a single session of movement can shift your mood within minutes. You feel better immediately - mood, energy, stress relief. The chemical conversation starts from session one.

But over weeks and months of consistent movement, something deeper begins to shift. Your nervous system recalibrates, your stress resilience builds, your sleep deepens, and your mood stabilises at a higher baseline. Your brain even begins to physically grow, producing new cells, strengthening connections, and becoming more resistant to the effects of stress and low mood. 

Luckily, you don’t need to train like an athlete or have to run marathons to get these benefits. 

For healthy adults, it's recommended that at least 150 minutes of moderate activity be spread throughout the week or even breaking that into 21 minutes most days is enough to start the chemical conversation to reap these benefits. 

And if that still feels like a lot, simply moving to break up long periods of sitting and doing some physical activity is better than doing none. 

The most important thing is finding movement you actually enjoy. A walk along the beach, a yoga class, a swim, a bike ride - the best exercise is the one you'll actually show up for. As always, check in with your GP or healthcare provider to find out what's right for your body and where you're starting from. 

 

 

References:

Allen, J. M., et al. (2018). "Exercise Alters Gut Microbiota with Transient and Independent Impacts on Body Composition." Medicine & Science in Sports & Exercise.

Goldfarb, A.H., & Jamurtas, A.Z. (1997). β-Endorphin response to exercise: an update. Sports Medicine, 24(1), 8–16. https://doi.org/10.2165/00007256-199724010-00002

Sparling, P. B., Giuffrida, A., Piomelli, D., Rosskopf, L., & Dietrich, A. (2003). Exercise activates the endocannabinoid system. NeuroReport, 14(17), 2209–2211. https://doi.org/10.1097/00001756-200312020-00015

Gershon, M. D. (2013). 5-Hydroxytryptamine (serotonin) in the gastrointestinal tract. Current Opinion in Endocrinology, Diabetes and Obesity, 20(1), 14–21. https://doi.org/10.1097/MED.0b013e32835bc703

Caplin, A., Chen, F. S., Beauchamp, M. R., & Puterman, E. (2021). The effects of exercise intensity on the cortisol response to a subsequent acute psychosocial stressor. Psychoneuroendocrinology, 131, 105336. https://doi.org/10.1016/j.psyneuen.2021.105336

Ghorai, S. (2024, May 1). The ultimate brain booster: Exercise and mental health. Stanford Lifestyle Medicine. https://lifestylemedicine.stanford.edu/the-ultimate-brain-booster-exercise-and-mental-health/

Health New Zealand | Te Whatu Ora. (2020). Eating and activity guidelines for New Zealand adults (Updated 2020). New Zealand Government. https://www.healthnz.govt.nz/health-professionals/guidance-standards/topic/nutrition/eating-and-activity-guidelines