Exercise has the unique ability to elicit adaptations in both the body and mind. In the world of superfoods, fountains of youth and the like, are we overlooking the unmatched, comprehensive health benefits of regular physical activity? In this article, I will focus on the positive mental effects of exercise. The commonly reported mental disease states, depression and anxiety, will be the focus. This article is not intended to diagnose or treat any conditions.

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Anxiety

    According to the National Institutes of Health (NIH), generalized anxiety disorder (GAD) is defined by persistent and excessive worry occurring on most days for at least six months, involving a range of concerns such as personal health, work, social interactions and routine daily life. A widely used screening tool for GAD is the Generalized Anxiety Disorder 7-Item Scale (GAD-7) - a brief, self-reported questionnaire designed to assess the severity of anxiety symptoms. Items on the GAD-7 address common manifestations of GAD, including difficulty relaxing, excessive worrying, restlessness, irritability, and other frequently reported symptoms. Despite its subjective nature, the GAD-7 has demonstrated strong validity and reliability in both clinical and research settings.

Depression

    According to the NIH, depression is one of the most common mental disorders in the U.S. A multifaceted disorder, genetic, biological, environmental and other factors likely contribute to the wide variety of symptoms. Understood as a "mood disorder," depression can affect how you feel, think and act. Diagnosis is made following a minimum of two weeks with depressive symptoms. The Patient Health Questionnaire-9 (PHQ-9) is commonly used to diagnose. Loss of interest, increased fatigue, and hopelessness are among the many potential manifesting symptoms of depression.

Prevalence of Anxiety & Depression:

    According to the World Health Organization’s report, Depression and Other Common Mental Disorders: Global Health Estimates, an estimated 4.4% of the global population—approximately 322 million people—are currently living with depression, making it the leading cause of disability worldwide. Recognized as a multifactorial disorder, depression arises from a complex interplay of social, psychological, and biological influences. As both a deeply intricate and critically important public health challenge, depression is projected to become the second leading contributor to the global burden of disease, measured in years lost to disability, following a recent 20% increase in global prevalence. Higher rates of depression have been observed among women, populations in countries with a medium Human Development Index, and studies utilizing self-reporting measures.

   The onset of depressive symptoms is multifactorial and often complex. Severe stressors, commonly referred to as “stress triggers," are hypothesized to contribute to the development of depression by disrupting normal brain function. Evidence suggests that early life stress may be predictive of an individual’s lifelong vulnerability or resilience to future stress-related disorders. It has been reported that major depressive disorder (MDD) in children and adolescents is strongly associated with recurrent depression in adulthood, comorbid psychiatric conditions, and increased risk for suicidal ideation, attempts, and completion. Approximately 8% of children are diagnosed with MDD, and among these individuals, functional impairments are commonly observed in academic or occupational performance, developmental progression, and social relationships. Current guidelines recommend screening for MDD in adolescents aged 12 to 18, while evidence remains insufficient to support routine screening in children under 12. In addition to environmental and psychological contributors, genetic predisposition plays a significant role in susceptibility to MDD and suicidal ideation. Notably, research findings suggest that adequate levels of physical activity may mitigate the risk of MDD and suicidal ideation, even among individuals with a strong genetic vulnerability. 

   The diagnosis and onset of depression are inherently complex, and as such, therapeutic approaches must be multifaceted. When considering self-care strategies, stress management and adaptive coping techniques are often seen as accessible and personalized interventions that can be integrated into daily life. As discussed in this article, research suggests that exercise can be a valuable tool in managing symptoms of anxiety and depression. However, it is important to recognize that exercise should be considered a complementary approach, not a substitute for other necessary forms of care or other evidence-based treatments that may be required to address the full scope of an individual’s needs.

    Bruce McEwen, a pioneering researcher in the field of stress physiology, introduced the term "allostatic load" to describe the cumulative impact of chronic stress on the body and brain. His research explored how various stressors directly influence brain function, highlighting the role of stress and trauma in mediating both physiological and behavioral responses. McEwen emphasized that strong emotional states, particularly fear, are primary drivers of these responses. He further noted that stress is a known precipitant and exacerbating factor in mood disorders, contributing to neuronal atrophy, hyperactivity, and structural brain changes. 

   McEwen also outlined the mechanisms underlying positive stress adaptation, a process known as allostasis, or "stability through change." Under typical conditions, the body’s adaptive systems respond effectively to stressors and subsequently return to baseline. However, allostatic load refers to the chronic, repeated, or excessive activation of these systems, which over time can overwhelm the body's ability to recover. This imbalance, when the cost of adaptation exceeds the capacity to restore equilibrium, is what McEwen termed the "price of adaptation." 

Dysregulation of the Stress Response:

The principle understanding of allostatic load, the cumulative physiological impact resulting from a repeated or chronic stress, can be applied across a range of stressors, with consideration for their dose-dependent effects. It is important to further reiterate, the goal is not stress avoidance, but stress regulation. While acute stress can drive beneficial adaptation, prolonged or poorly managed stress can result in physiological wear and tear over time. This distinction between adaptive short-term stress and harmful chronic stress is central to understanding how stress influences long-term health. Elevated allostatic load has been implicated in various negative health outcomes, including major depressive disorder and chronic anxiety conditions. Therefore, incorporating measures of allostatic load into broader health assessments may provide valuable insights into an individual's overall physiological resilience and vulnerability. 

Beneficial self-care aspects of exercise:

Runners Only "High"?

    The phenomenon commonly referred to as the "runner's high" is familiar to many. But what underlies this exercise-induced state of euphoria and well-being? While it was traditionally attributed to the release of endogenous endorphins, more recent research has highlighted the significant role of the endocannabinoid system (ECS). Characterized by elevated mood, reduced anxiety, and decreased pain sensitivity, the runner's high is now understood to be largely mediated by endocannabinoids. These effects appear to depend primarily on the activation of cannabinoid receptor 1 (CB1) in the brain, along with contributions from both central and peripheral CB1 and CB2 receptors.
    Building on McEwen’s findings that intense emotions and chronic stress can “precipitate and exacerbate mood disorders,” emerging research increasingly supports a bidirectional relationship between the endocannabinoid system (ECS) and emotional states such as anxiety and fear. The ECS has been described as having a “unique regulatory capacity for maintaining emotional homeostasis,” and is further characterized as a “regulatory buffer system for emotional responses.” These insights suggest that a well-functioning ECS plays a critical role in modulating stress and maintaining psychological resilience. The question then becomes: How can we intentionally engage this innate system to our advantage?

Exercise and the Endocannabinoid System (ECS):

   Dr. Cecilia J. Hillard, PhD, Director of the Neuroscience Research Center at the Medical College of Wisconsin, presented at the 2019 American College of Sports Medicine (ACSM) Annual Meeting in Orlando, Florida. Her talk focused on the effects of exercise on the endocannabinoid system (ECS), offering valuable insights into the physiological mechanisms underlying this relationship. For readers interested in a more in-depth overview of the ECS, a detailed breakdown is available in my previous article here.

   The central theme of Dr. Hillard’s presentation centered on mechanisms by which the body’s endogenous cannabinoid receptors can be activated. Among these, exercise emerged as the most natural and evidence-based method. The ECS primarily exerts its effects through two G protein-coupled receptors (GPCRs): cannabinoid receptor type 1 (CB1) and type 2 (CB2). These receptors are distributed throughout the body. CB1 receptors are predominantly located in the central nervous system, as well as in the liver and adipose tissue, whereas CB2 receptors are most abundant in immune cells and brain microglia. The following slide from Dr. Hillard’s presentation provides a detailed breakdown of the ECS and its physiological roles.
   

1. Exercise increases ECS, via enhanced ligand concentrations and increased CB1R density in multiple brain regions.
2. There appears to be a down-regulatory effect on the ECS with chronic exercise.
3. The ECS contributes to exercise-induced effects on pain perception and anxiety; and the rewarding effects of exercise.

Dose Dependent: Finding Your Ideal Routine

Remembering the FITT principles:
(F: Frequency, I: Intensity, T: Time, T: Type)

    In my previous article, “The Best Fitness Program: The One You Keep Doing” (here), I emphasized the importance of exercise adherence and the value of focusing on high-impact strategies without tied up in less critical details. When designing an exercise routine with mental health benefits in mind, two key variables deserve particular attention: Frequency (F) and Type (T).

   Existing research has examined the mood-enhancing effects of exercise, independent of fitness improvements. Their findings suggest that the frequency of exercise should be prioritized over duration or intensity. This is likely due to the cumulative effect of more frequent, natural “feel-good” experiences throughout the week, compared to fewer sessions, assuming a minimal yet not excessive threshold of exercise is met. In addition to these immediate benefits, it’s important to consider the broader subjective advantages, both short- and long-term, as discussed earlier.

    Once again, research supports the idea that choosing a form of exercise you enjoy is the most effective approach. When comparing both running (aerobic) and weightlifting (anaerobic), both groups resulted in significant reductions in depression symptoms compared to a control group (no exercise). Additionally, we can refer to studies investigating a comparison of aerobic and anaerobic exercise for the treatment of clinical depression. Their findings revealed that the antidepressant effects of exercise were observed in both types, suggesting that the benefits were not dependent on achieving an aerobic response.
    An increase in aerobic fitness may not be the primary focus when seeking the antidepressant benefits of exercise. By selecting a form of exercise that you enjoy, you are more likely to maintain a consistent routine and reap the same benefits as you would from a program driven by obligation. The most significant benefits come from engaging in enjoyable, consistent physical activity. This is further supported by research showing that among individuals with bipolar depression, exercise is often ranked as the most important component of comprehensive treatment programs.

    When accessing the right course of action for your personal self-care program, it is important to remember that all adaptations involve trade-offs, and the dose (frequency) and type will be highly individualized. Because of this, I encourage you not to strive for a "standard" or preconceived optimal routine but rather be aware of how you are feeling. I understand this can be difficult for some, and likely even more so in individual's with a susceptibility to mood disorder symptoms. However, by implementing this strategy you may be able to avoid the pressure of adhering to an unnecessary standard. Dr. Daniel Lieberman, PhD, from Harvard University sums this concept up nicely stating "humans evolved to be active for play or necessity, efforts to promote exercise will require altering environments in ways that nudge or even compel people to be active and to make exercise fun." Ultimately, adopting this mentality will lead to greater adherence which will enhance your desired results. 

Exercise as Treatment:

       When considering the role of exercise in a comprehensive health program, it’s crucial to address some of the fundamental mental health questions. One key questions is whether individuals experiencing depressive symptoms are choosing not to exercise, or if the lack of exercise is exacerbating their depression. The answer likely lies somewhere in between, as it varies from person to person.

   Research has shown that decreased fitness levels, reflected by a reduced physical work capacity (PWC), are common in individuals with anxiety and depression. A reduced PWC is often described as being "out of shape." This raises the classic chicken-or-egg question: Does getting in shape help alleviate depressive symptoms, or do depressive symptoms prevent individuals from exercising? Interestingly, when examining reduced PWC, it was found that individuals with depression and anxiety often have normal pulmonary function. This suggests that the reduction in physical capacity is primarily due to lack of activity, not a physiological limitation. Therefore, the main challenge becomes overcoming the initial barrier to physical activity, which is necessary to unlock the mental and physical benefits of consistent exercise

   An initial education period is often essential to overcoming the first hurdle in incorporating a comprehensive health program. Many times, it is our preconceived notions or beliefs that prevent us from starting, continuing, or changing our exercise routines. Feeling constrained by the need to adhere to a strict or specific form of physical activity can be a significant barrier to participation. By addressing and overcoming this commonly reported limitation, we can then focus on applying the FITT (Frequency, Intensity, Time, and Type) principles.

   When applying the FITT principles, our ultimate goal is to enhance the likelihood of long-term adherence. This is critical, as the primary barrier to achieving positive health outcomes is not selecting the wrong exercises, but rather a lack of consistent adherence. This is particularly true when developing exercise-inclusive treatment plans for individuals with mood disorders. Researchers have noted that "compliance rates are rather low due to reduced energy and lack of motivation," and it is not uncommon for individuals to experience "overstrain when participating in a training program." Therefore, tailoring exercise to individual preferences is not only essential for addressing the initial hurdle of low motivation, but also for ensuring gradual, sustainable progression as individuals begin their exercise routines.

  An important consideration in any comprehensive health program is setting both short and long-term goals. Following a tailored educational period, goal setting can provide greater motivation and a clearer direction moving forward. Research results have shown "resistance exercise training significantly reduced depressive symptoms among adults, regardless of health status, the total prescribed volume of training, or significant improvements in strength". By clearly defining your goals, you can more effectively navigate your progress, avoiding distractions from commonly sought-after areas of improvement. A more nuanced, personalized approach to assessment, implementation, and review is better suited to achieving mental and cognitive goals.

   Starting with the end goal in mind allows for the implementation of various strategies, preferences, and timelines. A skilled trainer can ensure that these defined goals are met, while allowing for flexibility along the way. By understanding your current cognitive and physical limitations, a trainer can assess the best course of action, making adjustments as necessary. Ongoing communication is crucial for providing appropriate variation within an exercise-inclusive treatment plan. Outside of the scope of fitness, you may also be participating in additional forms of therapy. Exercise and other therapeutic methods should not be viewed as competing for greater benefits, but rather as complementary tools that enhance each other. Again, researches have found that while exercise and psychological treatments for major depressive disorder (MDD) had no significant difference in their effects, both individually showed significant positive results, further supporting the idea that exercise can serve as a valuable adjunct to other forms of therapy.

    So, now that you have this information, both general and specific, what does it mean for you? How can you put it into practice, and what exactly should you implement? The key takeaway is simple: exercise, in any form you prefer, enhances mental health. The specific mechanisms, reasoning, or details behind it are secondary. Whether you enjoy running, resistance training, or playing a sport, these options are all available to you, and you can switch between them as needed. Whether you're looking for a mood boost, trying to break through a mental block, or supplementing other forms of care, the power of exercise to elevate your mood, improve your day, and, with consistent use, transform your life is perhaps its greatest benefit

 

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