This Is Exactly What Happens to Your Brain During and After Exercise

This Is Exactly What Happens to Your Brain During and After Exercise

From the first five minutes of class to years from now, working out can positively impact your brain and overall health, according to a leading sports neurologist. Here’s how.

By Vernon Williams, MDUpdated May 4, 2022


You know that exercise is good for you, but many people don’t realize just how important physical activity is for the brain. Exercise triggers hormones and other changes in your brain that affect mood, thinking speed, mental sharpness and even athletic performance. Some of these effects happen almost immediately during your workout and within hours afterward, while other benefits are realized over the course of days and months as you stick to your workout routine.

Here, I’ll break down exactly what is happening in your brain when your body is hard at work on the Peloton Bike or Peloton Tread, and how those benefits translate into better health and fitness overall.

During Your Workout

5 minutes: The brain gets an instant boost. As you ease into movement during those first few minutes, you enter the “priming stage,” where you experience a gradual increase in heart rate, breathing and blood flow to your muscles. At this time, oxygen and nutrients are also delivered to your brain, which promotes the growth of new neurons.

20 to 30 minutes: Endorphins and endocannabinoids are released. Endorphins are feel-good hormones produced by the brain. Endocannabinoids are similar body chemicals that improve mood, stress response, memory and more. These hormones are released during moderate and intense exercise in response to stress and other physiological changes that happen when you work out. These chemical messengers help reinforce a positive association with exercise. The same chemicals are also released whenever you do something pleasurable, such as eat a favorite meal, hang out with your friends or laugh at a good movie. In essence, they make your brain say, “Ahhh, I want to do this again.” And while the post-workout “high” is often attributed to endorphins, it’s likely that the release of endocannabinoids plays a major role in that “conquer the world” feeling you have after exercise.

After Your Workout

60 minutes: BDNF production increases. Exercise, especially HIIT, increases the production of an important brain chemical called brain-derived neurotrophic factor (BDNF). We still have a lot to learn about BDNF, but we know it’s a molecule that helps our brains work properly, especially when it comes to mood, learning and memory. You can think of BDNF as a substance that’s improving traffic, connections and communication within the brain, all while encouraging brain growth.

As we get older, BDNF production declines. However, according to several studies, including one published in Frontiers in Cellular Neuroscience, BDNF production spikes after a single HIIT workout. This increase is temporary (you’ll have to exercise regularly to see more permanent benefits), but it boosts focus and concentration in the short term.

2 to 4 hours: A second wave of brain chemicals are released. Here’s where the real magic happens. In addition to endorphins and endocannabinoids, other neurotransmitters, such as serotonin, dopamine and norepinephrine, begin to kick in 2 to 4 hours after your workout. These brain chemicals are pretty amazing, and they deliver messages between neurons.

For instance, serotonin sends messages that affect a wide variety of brain circuits relating to mood, sleep, appetite and more. Not having enough serotonin is associated with depression and low mood, while increased levels of serotonin have been shown in studies, including this one, to have a positive influence on mood, cognition and impulsivity (i.e. increasing your ability to think through decisions before you make them) in the short term. In the long term, a serotonin boost from exercise may help reduce the risk of depression, according to research published in JAMA Psychiatry that looked at the exercise habits of over 600,000 people.

Working out also increases norepinephrine, which improves your ability to pay attention and focus on tasks. Dopamine, the reward substance, is also released. Dopamine helps you feel a sense of satisfaction from exercise. It’s also been shown in research to play a role in working memory and mental flexibility. This is why many of my colleagues and I routinely exercise in the morning on surgery days.

12 weeks: A sustained increase in BDNF. Doing regular aerobic or HIIT sessions for a minimum of three months can spur additional production of BDNF, according to several studies. The short-term release we talked about earlier is associated with improvements in concentration and focus, but when you get more BDNF over time, that’s when you start to see the impact on brain size, particularly in the areas of the brain associated with memory. Good news: Rest days don’t interfere with this effect, so be sure to recover between hard efforts. One study found that exercising every other day over the course of three months was just as effective at increasing BDNF levels as exercising every day.

3+ months: A healthy brain, a healthy body and vice versa. Exercise increases insulin-like growth factor 1 (IGF-1), a hormone that plays a role in both overall physical health and brain health. Having a healthy level of IGF-1 helps your body stabilize blood sugar levels after you eat and improves insulin sensitivity. Exercise increases insulin receptor density within three months of regular exercise, which also helps the body process sugar more efficiently. Together, these things can have a positive impact on cognitive health, since poor metabolic health can increase your risk of cognitive decline. Most people don’t necessarily think of the way their body processes sugar as related to brain health but, at the end of the day, all of these things are linked to neurological function.

The Long-Term Benefits of Exercise

Fitness has a significant impact on cognitive function in middle age and in the senior years and it can increase your overall “healthspan,” or the number of years you live in good health. Long-term exercise (over months and years) is associated with a larger hippocampus, temporal lobe and frontal lobe as you age—which are the regions that are vulnerable to dementia—according to a 2021 review published in Behavioural Brain Research. Evidence of smaller or atrophic hippocampal volume has been found in individuals with dementia. Although there’s no direct “cause and effect” link just yet, it is generally felt that a larger hippocampus could be protective against dementia.

Being active may also help prevent age-related brain shrinkage, which starts happening around age 40 and can lead to cognitive decline, notes a review published in NeuroImage. Consistent exercise also reduces your risk of cardiovascular disease, which is also associated with higher risks of developing cognitive impairment and dementia.

Vernon Williams, MD is a board-certified clinical neurologist specializing in sports neurology and pain medicine; he is also a paid consultant member of the Peloton Health & Wellness Advisory Council. Dr. Williams is the founding director of the Center for Sports Neurology and Pain Medicine at Cedars-Sinai Kerlan-Jobe Institute in Los Angeles, CA. He passionately advocates for optimization of neurological health across the lifespan for his patients and peak performance clients. Follow him on Twitter.

This content is for informational and educational purposes only and does not constitute individualized advice. It is not intended to replace professional medical evaluation, diagnosis, or treatment. Seek the advice of your physician for questions you may have regarding your health or a medical condition. If you are having a medical emergency, call your physician or 911 immediately.