Exercise: A Key Foundation of Brain Health

The benefits of exercise include increased cardiovascular health, stronger bones and muscles, stronger connective tissue, enhanced overall fitness, athleticism, treatment of type 2 diabetes, prevention of osteoporosis  and improved appearance.  A vast amount of research shows improved brain health is another benefit of exercise (1); thus, another important reason to exercise.  It appears that fitness professionals and educators are very interested  in this new line of research.  In a recent seminar I conducted at a college there was standing room only, and the audience consisted of students and instructors from four colleges.  The question and answer section lasted about thirty minutes.  The audience was interested in learning much more about the brain and exercise, and specifically sources they could use that could assist in acquiring basic knowledge regarding the topic.

Often, fitness professionals fail to mention that exercise benefits the brain.   I suspect there are two primary reasons they fail to discuss the benefits.  One, they are not familiar with the research (this line of research is often conducted by scientists interested in the brain). Secondly, they have minimal knowledge of the brain and brain processes; thus they would rather not discuss this topic. The brain is arguably the most complex structure in the universe. This level of complexity may prevent discussion.  I suggest that trainers, coaches and other promoting exercise mention brain health in discussions on the benefits of exercise.  Most people are probably aware that the term brain health / brain fitness is a popular topic in the media, or by those promoting computerized brain training games.   Media outlets often fail to mention findings regarding computerized brain training are indecisive (2).  In addition, they do not  mention there are a myriad of studies showing exercise benefits the brain in a variety of ways. These findings are decisive.   There are computerized braining training games that offer benefits to the user, but in order to benefit the user specific criteria are required.  Those criteria are beyond the scope of this article.  Refer to Michael Merzenich’s book  Soft Wired to learn more about the qualities to look for when considering whether or not to purchase a brain training product (2).

I would like to make some suggestions regarding the two primary reasons I think fitness pros  fail to mention brains benefits of exercise.  First, I will address a lack of familiarity with the research.  Go to Google Scholar or PubMed and type in “brain and exercise” or “exercise benefits the brain” or any other phrase that is relevant.  Read the abstract and if it interests you look at the full paper.  Many full papers are available free of charge. With a little effort you will discover there is a lot of research supporting the benefits of exercise and brain function.  It isn’t necessary to be an expert on the brain to appreciate the value of the research findings on brain and exercise. Secondly, I will address the problem of brain complexity.  Muscle protein synthesis and neuromuscular adaptations to strength training are also complex topics, but that doesn’t stop trainers from mentioning them to trainees.  It is not essential that trainers acquire a deep understanding of the mechanisms that underpin muscle building or strength building.  It follows, that trainers do not need a deep understanding of the brain in order to tell trainees that exercise benefits the brain.  Many of the benefits of exercise involve a cascade of complex events; trainers are not dissuaded from mentioning those benefits just because they are complex.

Exercise improves memory and learning in humans and non-human animals.  Exercising individuals might be less susceptible to loss of thinking abilities associated with aging. One of the key mechanisms that contribute to these benefits is the growth of new nerve cells in an area of the brain involved with learning, spatial processing and memory (the hippocampus) .  Van Pragg (3) suggests that in addition to the growth of new nerve cells, other factors mediate the effects of exercise on the brain: changes in brain connections, increased density in the receiving area of the nerve cell, growth of new blood vessels, enhancement of chemical messengers and growth factors.  Van Pragg asserts “[e]xercise is a quantifiable activity the improves cognition in young and aged animals and humans.”

Mental health & neurodegenerative disorder?

Mental health is a component of physical health. All mental processes are generated by the brain.  Mental health is often referred to as if it is somehow distinct from brain health or that mental health is not quite as real as physical health.  “It’s all in the head” is a common phrase suggesting that mental health is not serious, or not even real.  This assumption is mistaken.  Eric Kandel, noble laureate, points out all mental health ailments are disorders of brain processing (4).

The antidepressant effect of exercise in humans has been shown to be just as potent as that of that of some medications .  Results in one study showed that after four months of aerobic exercise individuals with major depressive disorder demonstrated a significant therapeutic benefit (5).  Even after ten months those in the exercise group had significantly lower relapse rates than those in the medication group (received sertraline therapy).

Research shows that exercise is beneficial for individuals with Parkinson’s.  Goodwin and colleagues (6) conducted a systematic review and meta analysis of randomized controlled trials (RCTs) reporting on the effectiveness of exercise interventions on various outcomes (physical, psychological or social functioning, or quality of life) for people with PD.  The results indicated that exercise was beneficial with regards to physical functioning, health-related quality of life, strength, balance and gait speed for people with PD.

A review study conducted by Erickson and colleagues (7) examined various type of studies looking at an association between physical activity and brain volume, function, and risk for Alzheimer’s disease. After reviewing the studies it was concluded that there is convincing evidence that physical activity has a consistent and strong association with brain regions implicated in age-related cognitive decline and Alzheimer’s disease.

Exercise Recommendations

The majority of research examining brain and exercise is focused on aerobic exercise. There is a lot of research showing aerobic exercise benefits the brain.  Exercise doesn’t have to be strenuous to be beneficial, but it needs to be something beyond everyday physical activity.  Everyday physical activity might be something such as doing laundry or walking around the house or office.  These activities are not the same as exercise.  They generally do not become progressively harder, they lack structure and the body has adapted to these movements.  Even though exercise doesn’t have to be excessively stressful, it needs to consist of something more than the type of physical activity required to perform everyday tasks.  While both are superior to being sedentary, it is clear that exercise is needed to produce a variety of health benefits.

Davis and colleagues (8) conducted an experiment to test the hypothesis that exercise would improve executive function (high order cognitive functions).  The study involved sedentary, overweight 7- to 11-year-old children.  The participants were randomly assigned to an exercise program (20 or 40 minutes/day), or a control condition.  Blinded, standardized psychological evaluations were used to measure cognition and academic achievement. Functional magnetic resonance imaging (*FMRI) measured brain activity during executive function tasks.  A specific improvement on executive function and brain activation changes due to exercise were observed.

Smith and colleagues (9) performed a meta-anlaysis, examining the effects of exercise on neurocognition.   The studies used in the meta-analysis were  RCTs examining the association between aerobic exercise and neurocognitive performance.   Neurocognitive performance measures were attention and processing speed, executive function and memory.  The researchers concluded “[a]erobic exercise training is associated with modest improvements in attention and processing speed, executive function, and memory, although the effects of exercise on working memory are less consistent.”

In one study, participants with diabetes or metabolic syndrome showed an increase in brain-derived neurotrophic factor after 12 weeks of riding a stationary bike (10).   Brain-derived neurotrophic factor (BDNF) is a growth factor involved in neural plasticity processes  (growth of new neurons and neuron connections).

Wendy Suzuki (professor at New York University & author of Healthy Brain, Happy Life) designed a course that includes a combination of neuroscience lecture and aerobic exercise (11).  She was interested in answering whether or not performing aerobic exercise once a week for fifteen weeks could improve memory.  She compared the results of students in neuroscience class that includes exercise (aerobic exercise) with students in a neuroscience class that didn’t include exercise.  A significant improvement was found in response time, regarding a memory task, for those in the exercise group relative to the non-exercise group.  Even though an overall improvement was not seen in correct responses, just once a week exercise had a significant effect on processing speed, so with more frequent exercise it is maybe more benefits would have occurred.  What would have happened if participants exercised three to four times per week?

In another study Suzuki was involved in participants with traumatic brain injury were tested before and after an eight-week exercise program, that consisted of performing aerobic activity twice per week (12).  The exercise group was compared with a control group.  A significant improvement in mood and quality-of-life measures was found for those who were in the exercise group versus the control group.

Research indicates that anaerobic exercise can be also beneficial to the brain. In one study, learning performance was tested directly after a single bout of: high impact anaerobic sprints (2, 3 minute sprints separated by 2 minute rest), low impact aerobic running (40 minutes), or a period of rest, in 27 healthy participants (15 minutes) (13).  The main findings showed: the high impact group improved significantly on measures of learning performance, & the low impact group did not shown an effect on learning.

Michael Merzenich (neuroscientist) recommends that a variety of exercises are beneficial for brain health (2).  Each movement is represented by a specific motor program.  That is, each movement is represented by different neural connections (unique neurotag).  By learning different movements different connections are strengthened and become widespread throughout the brain.  Even a seemingly simple movement may require a relatively large portion of the brain.

Future Directions

Future research needs to investigate different types of exercise, different durations of exercise, compare how exercise influences various populations and examine exercise at different intensity levels.  Much of the current research has been conducted in rodents; more human research needs to done.

Key Points

A vast amount of research shows improved brain health is another benefit of exercise (1); thus, another important reason to exercise.

Trainers, coaches and other promoting exercise should mention brain health in discussions on the benefits of exercise.

Lack of familiarity or brain complexity should not dissuade trainers from mentioning the benefits exercise may have on brain function.  Trainers should review the research and consider brain complexity just as they do other complex exercise induced changes (muscle protein synthesis & neuromuscular adaptations).

Van Pragg (3) suggests that in addition to the growth of new nerve cells, other factors mediate the effects of exercise on the brain: changes in brain connections, increased density in the receiving area of the nerve cell, growth of new blood vessels, enhancement of chemical messengers and growth factors.

Exercise benefits brain health for different populations.

Aerobic and anaerobic exercise provide the brain with benefits.

Learning a variety of movements may lead to more brain connections (more neuro-tags).

Future research should include more human studies, and involve numerous type of exercises at varying intensities and duration.

There is plethora of evidence showing that exercise is beneficial to the brain.  Of course, total body health requires brain health.

 

* FMRI- A noninvasive biomedical imaging technique that employs a large magnet to detect changes in blood flow and oxygen consumption in the brain.  Blood flow and oxygen utilization increases in regions where neurons are more active, such as during the performance of a cognitive task. (Kandel, 2006, p. 438)

References

  1. A. Fernandez and E. Goldberg with P. Michelon, The SharpBrains Guide To Brain Fitness 2nd editon (SharpBrains Incorporated, 2013).
  2. M. Merzenich, Soft-Wired 2nd edition (San Francisco, CA: Parnassus Publishing, LLC, 2013).
  3. H. Van Pragg, “Exercise and the brain: something to chew on,” Trends in Neurosciences 32(2009): 283-290
  4. E. Kandel, In Search of Memory: The Emergence of a New Science of Mind (New York, NY: Norton, 2006).
  5. M. Babyak, J. Blumenthal, S. Herman, P. Khatri, M. Doraiswamy, K. Moore, W. Craighead, T. Baldewicz and K. Krishman, “Exercise treatment for major depression: Maintenance of therapeutic benefit at 10 months,” Psychosomatic Medicine 62 (2000): 633-638.
  6. V. Goodwin, S. Richards, R. Taylor, A. Taylor and J. Campbell, “The effectiveness of exercise interventions for people with Parkinson’s disease: A systematic review and meta-analysis,” Movement Disorders 23 (2008): 631-640.
  7. K. Erickson, A. Weinstein and O. Lopez, “Physical Activity, Brain Plasticity and Alzheimer’s Disease,” Archives of Medical Research 43 (2012) 615-621.
  8. C. Davis, P. Tomporowski, J McDowell, B. Austin, N. Yanasak, J. Allison and J Naglieri,” Exercise Improves Executive Function and Achievement and Alters Brain Activation in Overweight Children: A Randomized Controlled Trial,” Health Psychology, 30 (2011): 91-98.
  9. P. Smith, J. Blumenthal, B. Hoffman, H. Cooper, T. Strauman, K. Welsh-Bohmer, J. Browndyke and A. Sherwood, “Aerobic Exercise and Neurocognitive Performance: a Meta-Analytic Review of Randomized Controlled Trials,” Psychosomatic Medicine 72 (2010): 239-252.
  10. S. Tsai, Y. Chan, F. Liang, C. Hsu and I. Lee, “Brain-derived neurotrophic factor correlated with muscle strength in subjects undergoing stationary bicycle exercise training,” Journal of Diabetes and its Complications 29 (2015): 367-371.
  11. W. Suzuki, Healthy Brain, Happy Life (New York, NY: HarperCollins Publishers, 2014).
  12. Y. Lee, T. Ashman, A. Shang and W. Suzuki, “Brief Report: Effects of Exercise and Self-Affirmation Intervention after Traumatic Brain Injury,” Neuro Rehabilitation 35 (2014): 57:65.
  13. B. Winter, C. Breitenstein, F. Mooren, K. Voelker, M. Fobker, A. Lechtermann, K. Krueger, A. Fromme, C. Korsukewitz, A. Floel and S. Knecht, “High impact running improves learning,” Neurobiology of Learning and Memory 87 (2007): 597-609.
Jamie Hale