Can exercising the body improve the health of the mind?

A Brief History

“It is exercise alone that supports the spirits, and keeps the mind in vigor” Cicero ~65BC

The second president of the United States was quoted, “Exercise invigorates, and enlivens all the faculties of body and of mind…” (Kramer et al. 2006. p.1237). Through providing an up-to-date review of published scientific literature we want to investigate the claim that exercise has positive benefits for cognition. Most research in this field that has been conducted through analyses of numerous epidemiological, clinical trials. The absence of disease by primary prevention or the delay of disease progression by means of secondary prevention; also the preservation of executive cognitive function is one way to define a “healthy mind”. [7]

Epidemiological review

Over the past decade studies conducted using a self-report method demonstrated there is an inverse correlation between physical activity and age-related cognitive decline and the prevention of neurological disease. One study from an exercise intervention conducted a post assessment (6.2 years) test where 158 individuals out of 1740 men and women over the age of 65 developed Alzheimer’s dementia. Post adjustment of cofounding variables such as education level demonstrated that, “incidence rate for Alzheimer’s disease was significantly higher for individuals that exercised less than three times per week 19.7 per 1,000 person year) compared with those who exercised more than three times per week (13.0 per 1,000 person year)” [8]. These results suggest a form of dose-response relationship. Numerous scientific literatures that have been published to similarly support this claim. There is also literature that claims an inverse relationship between physical activity levels and age related cognitive decline. Although there may be substantial evidence supporting the relationship between physical activity and later cognitive function including the absence or delayed progression of neurological disease. There is some inconsistent findings observed that could potentially have risen from the use of self-report measures or the lack of operational and conceptual definitions of physical activity (type, duration and intensity). [7]

Clinical trial review

For approximately four decades, Colcombe and Kramer have conducted meta-analyses on published scientific literature that examined the exercise effects on cognitive function of healthy older adults [8]. Studies that qualified must utilize: randomized design for treatment group and controls. The results demonstrated a moderate effect size (0.48) between physical activity and cognition. The largest positive effect was found in executive cognitive functions such as, “planning, scheduling, working memory, inhibitory processes, and multitasking” [8]. More importantly these effects were larger when aerobic exercise was combined with strength and flexibility training. It is argued that even a small effect size is beneficial due to the complexity that is the dualist problem. [7]

How do we conceptualize the health of the mind?

In order for us to conceptualize the health of the mind we must define health. The World Health Organization’s definition of health states: “a state of complete physical, mental, social well-being and not merely the absence of disease and infirmity” [13]. With that in “mind”, through the American Psychology Association’s concise definition of mental states that the mental is the mind or its processes including thinking, feeling and related executive processes [14]. We now return to classify the health of the mind as some studies states: “directly or indirectly related to the mental health components of the World Health Organization such that it promotes well-being, prevention of mental disorders and, to provide treatment or rehabilitation for those who exhibit mental disorders.” [5]. Furthermore, the mental health components of the WHO defines wellbeing as realizing ones potential, their ability to manage normal life stresses, make positively contribute to their environment[13]. One may make the claim that, “Psychological distress is a term that refers to the emotional state, somatic symptoms, discomforts, and impaired coping associated with mental and physical health disorders” Kessler et al. (2002) viewed this as an indicator of general mental health. [6]

Cognitive aspects of the healthy mind

This article systematically analyzed three independent literatures that examined the relationship between physical activity and exercise on cognition, brain function and structure. It puts claim that habitual levels of physical activity can maintain and improve cognition and brain function. [8]

Age related decline

Executive cognitive function such as: memory, visuospatial ability, planning, scheduling and working memory tend to decline with age. It is alleged that regular exercise in older adults perform better in cognitive tasks than their sedentary counter parts, especially those who find enjoyment in high levels of physical activity. As a result, this leads to maintained cognitive function and an overall improved quality of life. Some mechanisms for this phenomenon are neurogenesis, brain plasticity and other possible molecular and cellular mechanism will be explored in a bit more detail later. [9] Furthermore, other mechanisms not explored in depth are related to:

  • Inflammation - inflammation that is present is associated with dementia related cognitive impairment. A study showed that post three week exercise intervention lab mice regained normal cognitive function and spatial memory with voluntary running. [9]
  • Increase in cytokines - Cytokines are chemical signals, studies show that increased levels of brain cytokines can protect neurons in the hippocampus and may improve cellular communication. [9]
  • Increased blood flow to the brain is one the most plausible mechanisms. Exercise causes vasodilation in critical regions in the body. This increase in blood flow causes an increase in concentration of oxygen and glucose, which are vital nutrients for the body. Furthermore, the increase in blood flow also results in increase pressure, causing dilation then contraction of cerebral muscles. This acts like a physiological cerebral “massage”. [9]
  • Exercise may also decrease the risk for cerebrovascular disease such as stroke caused by hypertension. Furthermore, a blockage from stroke could cause increase the risk of oxidative stress. [9]

Cortical Plasticity

Numerous literature has examined has supported the notion that maintenance of physical activity levels can improve if not sustain cognition and brain function. Such studies were conducted under observational human studies, clinical trials and animal research to determine molecular and cellular mechanisms. [8]

Observational Studies

Studies conducted concluded after a follow up after 6.2 years of 158/1740 individuals developed dementia. These individuals were 34% less likely to exercise three times per week. The relationship between fitness and cognitive ability was stronger in objective measures than subjective. [8]

Randomized clinical trials

These trials were conducted using randomized aerobic exercise interventions. The results were mixed due to lack of operational definition of cardiorespiratory fitness (determined by VO2 max), length and intensity, cognitive processes examined and other confounding variables such as age, health and socioeconomic status. Regardless, there was a moderate effect size for treatment interventions on normal (including decline of executive cognitive processes) and pathological cognitive processes. There is still little significant evidence supporting cognitive change, because of the reductionist nature of the study. Furthermore, fitness effects are not discriminate of a specific brain function. What can be concluded using functional magnetic resonance imaging (hereinafter fMRI), showed that through a six month aerobic exercise intervention (walking, stretching) of one hour per day; increased gray matter volume in the frontal and temporal cortex and white matter in the anterior region of the brain. The underlying mechanism remains an anomaly. The changes in volume may be indicative of enhanced cognitive performance. [8]

Animal Research

The use of animal research may serve as a great adjunct to human trials, such that it allows for better manipulation of otherwise uncontrollable variables such as: molecular and cellular mechanisms. Through this form of research it enhances our examination of factors that influence the brain and cognition. The study using lab mice is conducted over a 45 month period with access to voluntary aerobic exercise (wheel running). These mice had faster acquisition of mazes relative to their sedentary partners. In summary, exercise improved learning and retention of tasks related to the hippocampus. The molecular mechanisms that explain this phenomenon is that exercise increases the activation of mRNA and brain derived neurotropic factor (BDNF) in the hippocampus, cerebellum and frontal cortex. BDNF can improve dendritic outgrowth and synaptic plasticity improving neural networks. Amongst many other things BDNF acts as a neuroprotector, protecting these networks. This can explain the maintained cognitive function with exercise irrespective of age. Lastly, exercise increase Insulin Growth Factor 1 (IGF-1). It is alleged that increases in IGF-1 through exercise induces angiogenesis (production of new blood vessels) and neurogenesis (production of neurons). Both may influence cognition in the sense that, increases blood flow to the brain region could bring vital nutrients while the production of neurons can replaces the atrophying ones as a result of age. [8]

Personal Wellbeing – Improving the Psychosocial aspects

In one published systematic review of literature it is alleged that through analyses of mainly quantitative studies, the most common health benefit was associated with improved well-being. This was followed by decrease stress response, reduced distress, improved function in a social setting and vitality. [5]
What is more, studies published allege that participation in a socially engaging manner can contribute to mental health and overall life satisfaction. This is argued my stating, group activities enhance social connectedness, social support groups and peer bonding. [5] In another study physical activity is shown to enhance social participation, social skills and access to social support systems [11].
Randomized clinical trials of cross sectional and longitudinal studies that last at least twelve months demonstrate that physical activity may improve mood and decrease symptoms associated with depression and anxiety. This is especially true with major depressive; according to DSM classifications, who showed significant improvements relative to psychoactive treatments. Exercise in the form of running is inexpensive and easily accessible can enhance an individuals experiential well-being in addition to physical function. Shifting over to resistance interventions that occur over a 24 week period showed significant improvements in mood scores based on measurements obtained Exercise Induced Feelings Inventory. Yoga and other related non-traditional forms of physical activity showed significant decreases in perceived stress and negative affect [10].

Absence of Disease

In addition to maintenance of cognition and brain function, exercise can act as an adjunct in reducing prevalence or delayed progression of neurological diseases. Much of the establish literature focus their studies around dementia disorders including Alzheimer’s disease and other trauma related injuries to the brain. [8]
It is widely established that being sedentary leads to an impairment of physical health, social engagement and occupational performance. It is also to be noted that along with the physical benefits of exercise there are psychological benefits included. Some may argue that these physical and psychological benefits are correlated. The issue with current research is determining the optimal dose and the underlying mechanism. Based on observation and cross-sectional studies that utilized a self-report method, such studies support the claim that better mental health is correlated with increased engagement of physical activity. What is more, such a study showed that two to four hours a week had the largest difference. In addition, 65% of adults who exercised less than four hours had poorer mental health. In general it is said that poor mental health was associated with exercise that was less than two or greater than seven hours per week. This can be visually demonstrated by an inverted “U” relationship. Anywhere in between this duration of exercise was 1.39 times more likely to have better mental health irrespective of socioeconomic status [8].
The World Health Organization claims that 60% of the global population fails to achieve thirty minutes of physical activity daily, two thirds of that do participate in physical activity but do so insufficiently to obtain the associated health benefits. Physical activity is substantially low in the older age cohorts (44+ years old). With regular participation individuals are less likely to have major depression or a range of anxiety disorders classified by the DSM. The literature published surrounding this topic have shown an effect size of 0.72 moderate but borderline large, for treating anxiety and depression. It is important to note that this is less powerful than medication and psychotherapy. What is more, non-clinical volunteers, short follow up interviews, experimenter blinding may have led to some over-estimating. Another study conducted with exercise control groups and exercise with Sertaline (anti-depression medication) following a16 week duration at 70-85% max heart rate parameter showed that individuals in the exercise-medication group showed greater relapse into depression symptoms than the respective control group. With respect to, exercise being a prescription adherence to physical activity programs was higher when prescription was paired with a referral to an exercise specialist (8 months) compared to just a prescription from a doctor (6 months). [11].


Operational Definition of Exercise or Physical Activity

Physical activity simply defined by some independent studies refers to it as “a form of bodily movement produced by skeletal muscles that results in energy expenditure beyond resting level” (Canek). They go further to draw a distinction between the latter and exercise it must be: planned, structured, repetitive and purposeful subset of physical activity (Canek).
The World Health Organization provides us with a good backdrop into some of the concepts used in physical activity.
Physical Activity has different modalities, researchers try to explore these different modes of exercise to establish a dose-response that is critical to developing an exercise prescription for individuals.


You may hear these terms used a lot and this will provide us a foundation with respect to defining Exercise:

  • Type of physical activity - can take many forms: aerobics, strength, flexibility and balance are commonly used. [12]
  • Duration - length of time that an activity has been performed for. [12]
  • Frequency - The number of times an activity is performed, commonly expressed in bouts per week or sessions. [12]
  • Intensity Level - Usually indicates the level of effort exerted in an activity performed there are three types; two that comprises our main focus:
    • Moderate - WHO classifies moderate-intensity PA as 3-6 times the intensity of rest, and usually is rated 5 or 6 on a 0-10 scale based on personal capacity. [12]

* High Intensity - WHO classifies this as 6+ times the intensity at rest, and usually equates to a 7-8 on a scale of 10 based on personal capacity. [12]

  • Volume - Volume specifically speaks to strength or aerobics, it is hard to conceptualize as it incorporates the three concepts above. [12]

: definition
More information on this from the Canadian Society for Exercise Physiology Physical Activity Guidelines Glossary [3]

How much and what kind of exercise should I be getting?

The Canadian Society for Exercise Physiology have gone through great lengths to improving the recommended guidelines for Physical activity. This information can be found on very simple information posters on their website. [4]

What are the many ways to get Physical Active?

This section

Structured vs. non-structured

Aerobic vs. Anerobic

Individual vs. Team sports

Recreational vs. Competitive

Effects of Exercise Hypotheses

Physical activity has many benefits as we have explored, with compelling evidence supporting psychological benefits from running interventions. We will attempt to explore some exercise-psychological benefits hypothesis.

  • Expectancy Hypothesis - individuals expect to feel better so they report (self-report studies) feeling better. [2]
  • Sense of Mastery (self-efficacy) - Humans are motivated by a sense of accomplishment. Exercise allows us to gain this, which makes us feel better. [2]
  • Thermogenic Hypothesis - Increases in body core temperature is related to reductions in muscle tension, as a result we feel relaxed, enhanced mood and reduced anxiety. [2]
  • Endorphin Hypothesis - The release of endorphins (ex. endogenous opiates like dopamine) during exercise may result in positive mood effects. However, research from human trials are inconclusive. [2]
  • Serotonin Hypothesis - Neurotransmitters modulates mood, emotion and sleep. These neurotransmitters are increased during exercise and could be responsible for self-reported scores. It is important to note SSRI's (selective serotonin re-uptake inhibitor) prevent the re-uptake of these neurotransmitters, prescribed anti-depressants utilize this way to treat or alleviate depressive symptoms. [2]

Suggestion for future Research

1. Carek, PJ. Laibstain, SE. Carek, SM. (2011). Exercise for the treatment of depression and anxiety. Int J Psychiatry Med, 41(1):15-28. doi: 10.2190/PM.41.1.c.
2. Crocker, PRE. (2013). Exercise and Mental Health. Leith, LM. Kerr, GA. & Faulkner, GE. (Eds.), Sport and Exercise Psychology Custom Edition (pp. 3-26). Boston, Massachusetts.
3. Canadian Society for Exercise Physiology. (2011). Canadian Physical Activity Guidelines Glossary. Retrieved from
4. Canadian Society for Exercise Physiology. (2012). Canadian Physical Activity Guidelines. Retrieved from
5. Eime, RM. Young, J. Harvey, JT. Charity, MJ. Payne, WR. (2013). A systematic review of the psychological and social benefits of participation in sport for children and adolescents: informing development of a conceptual model of health through sport. Int J Behav Nutr Phys Act, 10,135. doi: 10.1186/1479-5868-10-98.
6. Kim, YS. Park, YS. Allegrante, JP. Marks, R. Ok H. Cho, KO. Garber, CE. (2012). Relationship between physical activity and general mental health. Prev Med, 55, 458–463. doi: 10.1016/j.ypmed.2012.08.021
7. Kramer, AF, Erickson KI, and Colcombe SJ. (2006). Exercise, cognition, and the aging brain. J Appl Physiol, 101, 1237–1242. doi: 10.1152/japplphysiol.000500.2006.
8. Kramer, AF. & Erickson, KI. (2012). Capitalizing on cortical plasticity: influence of physical activity on cognition and brain function. Trends Cogn Sci, 11(8), 342-8. doi:10.1016/j.tics.2007.06.009.
9. Nazimek, J. (2009). Active body, healthy mind. The Psychologist, 22(3), 206-209.
10. Penedo FJ, Dahn JR. (2005). Exercise and well-being: a review of mental and physical health benefits associated with physical activity. Curr Opin Psychiatry, 18(2):189-93. doi:10.1097/00001504-200503000-00013
11. Saxena, S. Ommeren, MV. Tang, KC. & Armstrong TP. (2005). Mental health benefits with physical activity. J Ment Health, 14(5):445-451. doi: 10.1080/09638230500270776
12. World Health Organization. (2010). Global recommendations on physical activity for health. Retrieved from
13. World Health Organization. (2006). Constitution of the World Health Organization. Retrieved from
14. Vandenbos, R. (2009) APA Concise dictionary of psychology. Washington. American Psychology Association.
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