Physical Exercise and the Brain 

As you learn in this course about living a healthy lifestyle in order to maintain or increase your brain health, you will realize how important the component of physical activity is to your success.  In this lesson, we will learn about many of the processes and changes that occur in the brain when we exercise. We will discover that long-term physical exercise can result in changes in the brain, which translate into benefits that can positively impact your life, your health, and your brain itself. 

Exercise may be even more important than ever in this time of sheltering in place.  We all still need to keep our minds and our bodies strong.  There should be no doubt in your mind that exercise is good for your body.  And, as we have mentioned  it many times in other lessons, you probably already know it is good for your brain, as well. Why else would you go out and do something that makes you breathe hard and sweat? In this week's lesson, we will learn what happens in the brain when we exercise, and what causes these changes. It may seem a little scientific at times, so don't worry as much about the details as the message. As you read, you will realize that these changes fit in nicely with our discussions on the brain in general. 

When discussing the advantage of exercise and the brain, we will be referring to aerobic exercise as well as strength training.  Examples of aerobic exercise include running, jogging, brisk walking, swimming, and cycling.  Examples of strength training (sometimes referred to as resistance training) include lifting weights, doing push ups, sits ups, jumping, or heavy gardening (digging or shoveling).

According to research, the following are some short-term effects of aerobic exercise in the brain: 

• Memory:  Researchers found that a short burst of moderate exercise can enhance the consolidation of memories in both healthy older adults and those with mild cognitive impairment.  This study is unique to most of the others because it shows that even a short session will show results (Brief Exercise Immediately Enhances Memory, UCI Study Finds, 2012).  These immediate benefits can probably be attributed to increased blood flow to the brain.  

• Cortisol release:  Cortisol is referred to as a stress hormone.  Short-term increases in cortisol levels are associated with cognitive improvements, such as enhanced inhibitory control.  These levels begin to rise after 30 minutes.  However, chronic exposure to high levels of cortisol (such as a stressful lifestyle) has negative results on cognitive control and can be toxic in the brain.  It can decrease a protein called Brain Derived Neurotrophic Factor (BDNF), which is helpful for memory and decreasing depression.  The cortisol released during exercise has positive benefits, including decreased stress and increased stress-coping behaviors.  It also reverses the decrease in BDNF normally associated with stress, thereby improving depression.  The important take-away from this is that the release of cortisol in the short term is a good thing, while long-term release of cortisol is not.  

Below is a visual on the difference in our functioning between short-term release of cortisol (such as in an exercise function) and long-term release of cortisol (due to chronic stress).

• Euphoria: Continuous exercise over a longer period of time can produce short-term euphoria, which may produce feelings of contentment, elation, and well-being.  Research suggests that several “euphoriants” are responsible, including phenethylamine (a stimulant), beta endorphin (an opioid), and anandamide (a cannabinoid).  These euphoriants may remain in the system for the remainder of the day.  Endorphins in particular have been shown to improve mood for the remainder of the day, and that mood is positively correlated with overall daily physical activity.  Note:  Endorphins do not only improve mood--they also block the transmission of pain. 

Long-term effects of aerobic exercise include:

• Increased neuron growth and positive neuroplasticity.

• Aerobic exercise promotes neurogenesis by increasing production of neurotrophic factors.  Neurotrophic factors are the proteins responsible for growing and maintaining neurons. So, in response to aerobic exercise, the body releases these neurotrophic factors, which stimulate neuron growth (neurogenesis) (Physical Fitness Beefs Up the Brain, 2013).

• Consistent exercise after several months marked improvements in executive function and increased gray matter volume in multiple brain areas, especially those connected to cognitive control.  Remember that increased gray matter means that new neurons are being formed.  These neurons will develop in different areas of the brain.  Depending on where the neurons grow, you will see certain cognitive changes.  

As we age, we gradually lose volume in the hippocampus, thus affecting memory.  Sedentary adults over age 55 show a 1 to 2 % decline in hippocampal volume a year.  A study of regular exercisers showed increased volume of the hippocampus by 2.12% and the right hippocampus by 1.97% over a one-year period.  Those in a low-intensity stretching group who had a higher level of fitness at baseline showed less hippocampal volume loss than for those who did not have the previous high level of fitness.  This suggests that exercise may be protective against age-related cognitive decline.  Those who exercise more over a given period have greater hippocampal volumes and better memory function (Weir, 2011).

• Recent research also shows improved white matter structure.  Exercise appears to make the axons in the white matter more compact and efficient, thus improving communication between brain regions.  Some researchers found a strong link between the structural strength of white matter and physical activity (Bergland, 2014).

• Moderate improvements in the anterior cortex, parietal cortex, cerebellum, caudate nucleus, and nucleus accumbens.  What are the functions of each of these brain regions?  

  • Prefrontal and anterior cingulate cortices – required for the cognitive control of behavior, particularly working memory, attentional control, decision-making, cognitive flexibility, social cognition, and inhibitory control of behavior; implicated in attention deficit hyperactivity disorder (ADHD) and addiction. 

  • Nucleus accumbens – responsible for reward, perception, motivation, and positive reinforcement; implicated in addiction.

  • Cerebellum – responsible for motor coordination and motor learning.

  • Caudate nucleus – responsible for stimulus-response learning and inhibitory control; implicated in Parkinson's disease, Huntington's disease, and ADHD.

  • Parietal cortex – responsible for sensory perception, working memory, and attention (contributors, 2015).

• Higher physical fitness (measured by maximum oxygen capacity) is associated with better executive function, faster processing speed, and greater volume of the hippocampus, caudate nucleus and nucleus accumbens.

3.  C-fos:  Increased release of c-fos, a transcription factor, occurs when neurons fire impulses.  Research suggests that consistent aerobic exercise, particularly endurance training, can actually prevent the development of certain drug addictions, and is an effective adjunct treatment for drug addiction.  Consistent aerobic exercise in duration and intensity reduces drug addiction risk.  In particular, aerobic exercise decreases psychostimulant self-administration, reduces the release of drug-seeking neurotransmitters in the brain, and changes the dopamine receptors to further make addiction less appealing in the brain.  Psychostimulants are drugs that show an increase in psychomotor activity (such as amphetamine, methylphenidate, or caffeine).  They may also produce antidepressant or mood-elevating properties.  

• Antidepressant effect:  Probably through increased BDNF to the brain.  Research found that exercise is more effective than a control intervention and comparable to psychological or antidepressant drug therapies.  Another study suggested that it is effective as an adjunct treatment with medication.  

• Improvement of anxiety:  Researchers found that people who have high levels of anxiety but who also have high levels of activity are less likely to panic when faced with a challenge.  Researchers suggest that the exercise may ward off panic attacks.  It may also be useful for those who are at risk for developing anxiety disorder (Weir, 2011).

• Greater scores on neuropsychological function and performance tests (tests which focus on intelligence, memory, language, executive function, and more).  Exercise has been shown to improve a number of cognitive control aspects and memory functions.  They include attentional control, attention span, information processing speed, cognitive flexibility (ability to switch tasks), inhibitory control, working memory, declarative memory, and spatial memory.  There is actually a reciprocal relationship between exercise and cognitive control:  improvements in cognitive control (such as attention and inhibitory control) increase a tendency to exercise.  Sometimes, this is seen after just one exercise bout, with more success following consistent exercise at a regular basis.   Would you like to see what type of tests are used to determine cognitive function?  Wikipedia has a great page, which provides names and links to some of them.  

In a review of literature (O'Connor, 2010), it was determined that resistance training does indeed benefit both brain health and mental health.  Several studies were cited, which describe the benefits of a strength training program.  Here are some of the highlights:

• In a 2010 study, it was found that resistance training was a meaningful intervention for people suffering from anxiety.  When questioning whether this training should be high intensity (80% of maximum weight possible) or moderate intensity (50 – 60% of maximum), it was found that anxiety was better reduced with moderate intensity.

• In several studies, it was found that resistance training improved several aspects of cognition in healthy older adults.  One of the most profound effects was the improvement in memory.  It was also found that executive functioning was significantly improved with resistance training. 

• A large number of studies (18) examined resistance training and depression with mixed results.  Several showed a significantly positive effect from the resistance training, while others showed little change in depression.  Four studies were done with clinically depressed adults and found large reductions in depression from resistance training.

• In chronic fatigue, exercise was found to be overwhelmingly beneficial, even more so than drugs or cognitive-behavioral interventions.  And a strength-training-only intervention found the greatest improvements in chronic fatigue.

• Resistance training was shown to improve self-esteem in healthy younger and older adults as well as cancer, cardiac rehabilitation, and depressed patients.

• It was found that physically active people have more healthy sleep patterns and a lower risk of sleep apnea.  People with depression and sleep disorders showed a 30% improvement in sleep following a strength training intervention.  These results appear to become most effective after 8 to 10 weeks of consistent resistance training. 

• Overall, it was suggested that the improved cognition from exercise is likely due to adaptations involving the new cells created in the brain, the increase in neurotransmitters, and the increase in new brain blood vessels for better oxygen delivery and waste product removal.  

There is no consensus on the recommended amount of exercise needed for improvement, although 150 minutes a week—30 minutes per day, 5 days per week—is commonly recommended for body benefits.  For brain benefits, however, it appears that more is better, and many studies use a 60-minute session.  A shorter session may not produce the same results, but will still provide some benefit.  The Department of Exercise Science at the University of Georgia maintains that even briefly exercising for 20 minutes facilitates information processing and memory functions (Posit Science, n.d.).  

When people think of grandmothers, they may think of old women who knit, bake cookies, and who don’t do very much outside the home.  But in South Africa, many grandmothers are the sole caregivers of grandchildren whose parents have passed away from HIV/AIDS. Though women in South Africa don’t play soccer, in Limpopo, grandmothers, known as the “Vhakegula Vhakegula,” or the “grannies grannies,” are forging new ground.  They play soccer twice a week, primarily for exercise.  In the process they also receive peace of mind and forge new friendships.  Many of them look at exercise as their medicine, and believe it prevents them from getting sick.  Many have overcome medical conditions they had prior to playing soccer, including difficulty sleeping.  Go to this webpage and watch the video about these amazing soccer grannies: http://www.karmatube.org/videos.php?id=8021 

The BHQ Connection: The BHQ website reinforces your lesson – exercise is good for the brain as well as the body. In the first article linked below, the “Golden Duo” of physical and mental exercise is mentioned as a great way to keep your body and your brain in tip-top shape . But most neuroscientists support the idea of a “Golden Triangle” of mental and physical health that includes; brain training, physical exercise and socialization as ways to increase your chances of better cognitive functions. When you’re seeking the optimum healthy lifestyle – don’t forget to include time with friends - we’ve added an article about that, too.  Just remember to apply the socialization skills we learned last week for social distancing right now.  You can even include friends in your (from home) exercise routines to get the best possible benefit and enjoyment from your workouts (joy is good for the brain).

We have covered many of the processes of the brain and the changes that occur with exercise.  As we go back and review, we find that long-term physical activity can result in changes in the brain which translate into better:

• memory 

• cognitive function

• executive function 

• processing speed 

• mood

• stress response 

• inhibitory behavior

• working memory 

• attention 

• neuronal activity

• sensory perception

• motor coordination

• protection against drug addiction

• protection against depression

• response to anxiety

• intelligence

• less chronic fatigue

• improved sleep

• less anxiety

• improved self-esteem

Is exercise a part of your brain-healthy lifestyle?

Bergland, C. (2014, September 22). Why is Physical Activity So Good for Your Brain? Retrieved from Psychology Today: https://www.psychologytoday.com/blog/the-athletes-way/201409/why-is-physical-activity-so-good-your-brain

Brief Exercise Immediately Enhances Memory, UCI Study Finds. (2012, November 26). Retrieved from UCI Press: http://news.uci.edu/press-releases/brief-exercise-immediately-enhances-memory-uci-study-finds/

Fairbank, R (2022). New Study Strengthens the Link Between Exercise and Memory. Retrieved from The New York Times, https://www.nytimes.com/2022/10/07/well/move/exercise-memory.html

Human Longevity Project. (2018). Episode 3: Diet and exercise: The surprising habits of healthy populations. Retrieved from: humanlongevityfilm.com [Resource was privately purchased and is not available online without purchase].

Mercola, J. (June 29, 2018). For optimal brain and nervous system health, you need to exercise your leg muscles. Peak Fitness. [Website]. Retrieved at: https://fitness.mercola.com/sites/fitness/archive/2018/06/29/leg-exercise-importance-on-brain-nervous-system-health.aspx

contributors, W. (2015, July 20). Neurobiological effects of physical exercise. Retrieved from wikipedia, The Free Encyclopedia: https://en.wikipedia.org/w/index.php?title=Special:CiteThisPage&page=Neurobiological_effects_of_physical_exercise&id=672200978

O'Connor, P. e. (2010). Mental health benefits of strength training in adults. American Journal of Lifestyle Medicine, 377-396.

Physical Fitness Beefs Up the Brain. (2013, August 28). Retrieved from Brain Facts: http://www.brainfacts.org/across-the-lifespan/diet-and-exercise/articles/2013/physical-exercise-beefs-up-the-brain/

Posit Science.  (n.d.).  Physical exercise for brain health.  [Online article].  Retrieved from: https://www.brainhq.com/brain-resources/everyday-brain-fitness/physical-exercise

Weir, K. (2011, December). The Exercise Effect. Retrieved from American Psychological Association: http://www.apa.org/monitor/2011/12/exercise.aspx