Depression is one of the most common mental health issues, affecting over 320 million people globally.
Research shows that exercise may be an effective treatment option for many battling this disabling condition.
Key Facts:
- Exercise has comparable antidepressant effects to medications and psychotherapy in clinical trials.
- Both aerobic and resistance training reduce depressive symptoms, with a combination providing maximal benefits.
- The biological mechanisms linking physical activity to improvements in mood are still being unraveled.
Source: Mol. Psychiatry (2023)
Exercise as Antidepressant Therapy
While best known for its physical health benefits, exercise has increasingly been recognized to enhance mental well-being.
Research over the past few decades provides robust evidence that being physically active reduces risk of depression.
Exercise also demonstrates clear mood-boosting effects for those currently battling the condition.
Multiple rigorous clinical trials find:
- Aerobic activities like walking, jogging, or cycling significantly reduce depressive symptoms. The benefits start to occur with just a few sessions per week.
- Resistance training using weights or resistance bands also lowers depressive severity similar to aerobic workouts.
- Combining aerobic and resistance exercise works best, speeding and amplifying improvement.
In head-to-head tests, exercise matches leading depression treatments like antidepressant medications and psychotherapy in efficacy.
Exercise also outperforms control conditions like stretching that account for social contact or other nonspecific effects.
Analyses indicate a “dose-response” phenomenon, where greater amounts of exercise lead step-wise to larger antidepressant effects.
Public health targets of at least 150 weekly minutes of moderate exercise or 75 weekly minutes of vigorous exercise plus twice weekly strength training provide a reasonable starting prescription.
How Exercise Modifies Biology to Treat Depression
Animal research implicates complex neurobiological pathways like serotonin, norepinephrine, inflammation, stress hormones, neurotrophic factors, and cellular plasticity and resilience in the antidepressant effects of exercise.
However, clinical studies attempting to link specific biological mechanisms to improvements in human depression have yielded inconsistent results.
Reasons for the mixed findings likely include:
- Considerable heterogeneity in how depression manifests between individuals
- Difficulty measuring central nervous system changes indirectly through blood tests
- Varying depression severity, health status, and exercise responses between studies
- Challenges accounting for factors like medications, diet, sleep, stress, or light exposure
Rapid advances across scientific fields provide hope for cracking exercise’s mood-related code.
For example:
- Expanding access to advanced “multi-omics” technologies now allows researchers to perform in-depth profiling of how exercise alters gene expression patterns, protein networks, metabolite fluxes, physiological processes, and neurological function simultaneously in the same individuals.
- Increased data sharing, analytical methods leveraging machine learning, and cross-disciplinary collaborations empower more holistic study of the multifaceted exercise-depression interface.
- Large federally-funded research networks could systematically examine exercise’s neurobiological impact across diverse, real-world populations while simultaneously conducting wide-scale clinical trials of exercise treatments.
In time, decoding exercise’s multifactorial antidepressant effects may uncover new pathways driving risk for depression in general.
This would offer novel targets for alternative treatment types while providing valuable insights into the poorly understood pathophysiology underlying this pervasive, disabling condition.
Neurobiological Mechanisms of Exercise for Depression
Neurotransmitter Modulation
Exercise increases the availability of neurotransmitters such as serotonin and norepinephrine, which are commonly targeted by antidepressant medications.
This helps improve mood and cognitive function.
Brain-Derived Neurotrophic Factor (BDNF)
Physical activity elevates levels of BDNF, a protein that supports neuron growth and survival.
Higher BDNF levels are associated with improved brain plasticity, which may alleviate depressive symptoms.
Endorphin Release
Exercise stimulates the production of endorphins, the body’s natural painkillers and mood elevators.
This leads to the ‘runner’s high’ and contributes to mood improvement.
Reduction of Inflammatory Markers
Chronic inflammation has been linked to depression.
Regular exercise reduces systemic inflammation, potentially decreasing depressive symptoms.
Hypothalamic-Pituitary-Adrenal (HPA) Axis Regulation
Exercise can normalize the HPA axis function, which is often dysregulated in depression, leading to better stress response and mood regulation.
Psychological and Social Mechanisms
- Improved Self-Efficacy: Regular exercise improves perceptions of self-efficacy and accomplishment, which can counter feelings of helplessness and low self-esteem in depression.
- Stress Reduction & Relaxation: Physical activity provides a healthy way to cope with stress, reducing its mental health impact.
- Social Interaction: Group exercises or fitness classes can enhance social support and connectivity, alleviating loneliness and depressive symptoms.
- Cognitive Function Improvement: Exercise has been shown to enhance cognitive functions like memory and executive function, which can be impaired in depression.
Exercise Recommendations for Depression Treatment
Included below are some evidenced-based exercise recommendations to help treat depression.
Aerobic Exercise (AEx): Activities like brisk walking, jogging, swimming, or cycling. Easily accessible and can be adjusted for intensity.
Resistance Exercise (REx): Weight lifting or bodyweight exercises. While less studied than AEx, it’s beneficial for depressive symptoms and should be incorporated.
Frequency: Exercise should be regular, ideally 3 to 5 sessions per week. This consistency is crucial for achieving antidepressant effects.
Duration: Each session should last approximately 45 to 60 minutes. This duration is supported by evidence showing optimal benefits for mental health.
Intensity: Exercise should be at a moderate to vigorous intensity. The intensity can be tailored based on individual fitness levels and may be guided using the Karvonen heart rate method. Initial intensity may be lower for individuals with low fitness levels or severe depression, gradually increasing as tolerance improves.
Combination of AEx and REx: Ideally, a combination of both AEx and REx should be prescribed. This ensures improvements in both cardiovascular and muscular fitness, which are beneficial for overall health and depression.
Related reading: Evidence suggests running therapy as effective as antidepressants to treat depression.
Implementation of Exercise to Treat Depression
While further research continues elucidating the precise mechanisms, ample clinical evidence already supports deploying exercise to combat depression now.
However, exercise remains largely ignored or underutilized in real-world treatment settings.
Reasons for exercise’s limited role likely involve providers’ lack of training for prescribing doses appropriately and monitoring response, poor coordination across mental health disciplines, and low confidence that patients will adhere sufficiently to gain mood benefits.
Improving exercise implementation requires a multifaceted approach:
- Expanding education for healthcare providers on exercise dosing, tracking, and safety specifically for depression management
- Developing specialized services improving linkages across mental health providers, exercise coaches, gyms, and community programs
- Employing smartphone apps, wearables, appointment reminders, incentives, and peer support to promote accountability for completing prescribed regimens
- Studying optimal ways exercise combines with medications, therapy, light therapy, brain stimulation, nutrition, stress management, purpose-promotion, or microbiome/immune targeted treatments
With personalized, integrated exercise prescription and resources supporting follow-through, the vast majority battling depression likely stand to gain significant respite from its disabling toll through physical activity’s safe, accessible mood benefits.
References
- Study: The role of exercise in the treatment of depression: biological underpinnings and clinical outcomes
- Authors: Ross et al. (2023)
