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The effect of exercise on the brain

You know that feeling you get after you crush a workout? You feel high, euphoric, like you’re ready for the next challenge. It’s not just a good feeling, it’s a real biochemical change happening in your body. Here’s what the science has to say about getting high naturally.

Feeling mentally good is a common side effect of exercise, also known as ‘runner’s high’. Exercise has numerous mental and physical benefits to human health which have been extensively researched. One study observed the effects of exercise on rates of depression by asking a group of participants to attend exercise classes for ten weeks. The researchers found that the intervention group experienced a 30 percent decline in depression.

Exercise has also been shown in research to improve rates of anxiety and other mood disorders, as well as decrease stress, improve mental clarity and decision making, regulate your body weight and improve cardiovascular functionality. So what happens in the body when you exercise that causes these potent health effects?

When you first start exercising, your body responds to the physiological adaptation as a source of stress. Stress has a bad rap, but it isn’t always bad; in fact, stress helps your body get physically ready to fight or flight. This ‘fight or flight’ mode was an evolutionary adaptation to protect our ancestors to have a boost of energy to fight or flee predators and threat. When you exercise, your heart rate increases and your cortisol and adrenaline increase - two hormones associated with stress.

This is then met with the release of a specific protein known as brain-derived neurotrophic factor (BDNF). BDNF protects your body and brain from the negative effects of chronic and acute stress and promotes neuroplasticity. This was explored in a study published in 2002 that was conducted on mice, that saw an increase in BDNF after physical activity. BDNF has been shown in research to act like a ‘reset’ button in the brain, to improve decision making and rational thinking; partially why you feel so good after exercise.

Working concurrently to this are endorphins - chemicals that are released in the brain as a response to the perceived moment of physical stress (i.e. exercise). Endorphins act as analgesics, meaning they reduce the perception of pain, triggering a positive feeling in the body similar to the effects of morphine, as explored in this study.

But more recent research has come out that suggests that endorphins and BDNF are not the main mechanism for that euphoric high you feel after working out.

Located throughout our body is a group of receptors called cannabinoid receptors and are part of the endocannabinoid system (ECS). This system is responsible for a number of physiological and biochemical processes in the body, largely around helping your body reach homeostasis. If you’re overheating, the ECS is responsible for regulating your body temperature by increasing sweating. But, as more and more research comes out about the ECS system, it may indicate that it has more to do with the feeling of euphoria post-exercise than scientists initially believed.

Firstly, endorphins are large molecules. Some researchers have argued that they are in fact too big to pass through the blood-brain barrier, so as well as they might diminish feelings of pain in the muscles, they are unlikely to have a direct effect inside the brain, where any real high would originate. So what is causing that natural high?

Endocannabinoids are essentially like naturally occurring cannabis. Cannabinoid molecules that are naturally found and produced in the body are small enough to cross the blood-brain barrier and act on certain receptors that would result in a euphoric high feeling in the brain.

A study published in 2015 examined the ‘runner’s high’ by looking at what happens in the brain of mice before and after exercise. The researchers found that exercise increases endocannabinoids, which inhibits analgesia, meaning that actually the decreased perception of pain may just be due to the endocannabinoids rather than endorphins.

To test this theory, the researchers gave the mice certain drugs that would block the endocannabinoid system, the mice did not experience the same cognitive and hormonal benefits of exercise. In another study, a lipid-soluble endocannabinoid called anandamide was found in high concentrations in the blood after exercise; further supporting the theory that the ECS system is more responsible for the natural high than any other biological mechanism.

If you want to get high naturally, start exercising. It will improve your mood, decision making and mental clarity. So if you’re feeling bad, exercise is a scientifically backed treatment with guaranteed benefits and no side effects - what’s not to love?

If you're yet to be convinced, here are THREE reasons why you should exercise today:

1. You’ll biochemically feel better.

Exercise increases brain-derived neurotrophic factor (BDNF), which acts as a sort of ‘reset’ button the brain, making you feel clear minded, better at decision making and more emotionally raional. Endorphins are also released that trigger feelings of happiness and decrease the perception of pain. And the endocannabinoid system (ECS) produces anandamide - the chemical that’s part of the system that moderates the psycho-active euphoric effect of marijuana. All these make you feel GOOD.

2. Your brain will immediately work better.

Exercise encourages more blood flow in the brain, meaning more energy and oxygen are transported to the brain, making it perform better. The hippocampus, the region of the brain associated with learning and memory, actually increases as a result of regular exercise. One study found that after only 20 minutes of aerobic exercise, concentration, focus and memory all improve.

3. You’ll handle life better.

A study published in 2016 found that 30 minutes of exercise decreased emotional irrationality and responsiveness in a group of participants. Another study found that exercise was associated with mental resilience and triggers a diminished inflammatory response to stressful situations. This is exercise promotes the growth of new neurons in the ventral hippocampus, making us better adapted to deal with the daily stressors of life.

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