"It is exercise alone that supports the spirits, and keeps the mind in vigor." –– Marcus Tillius Cicero
Every year, the multibillion dollar health and fitness industries go into high gear, pushing consumers to start eating healthfully, losing weight, and getting great physical workouts.
As we help our patients process these messages, we must remember that the oldest and safest mode of exercise is simple and inexpensive: walking. And as Cicero suggested so many years ago, physical activity is key to mental vitality.
For example, a literature review of 29 randomized controlled trials found that aerobic exercise training has substantial benefits for neurocognitive performance, particularly aspects of attention and processing speed, executive function, and memory (Psychosom. Med. 2010;72:239-52). In addition, a study using male college students either running on a treadmill or cycling on a stationary bike for 50 minutes at 70%-80% of maximum heart rate found that exercise of moderate activity activates the endocannabinoid system, leading to exercise-induced analgesia (Neuroreport 2003;14:2209-11).
And in yet another study, researchers used a microarray to identify a profile of exercise-regulated genes in the mouse hippocampus. They found that exercise upregulates a neurotrophic factor signaling cascade that has been involved in the actions of antidepressants (Nat. Med. 2007;13:1476-82). Physical exercise keeps the brain active. A randomized controlled study of male patients with chronic schizophrenia and matched healthy subjects found that hippocampal volume is plastic in response to aerobic exercise (Arch. Gen. Psychiatry 2010;67:133-43).
At least two recently published studies corroborate these correlations between physical activity and mental health. A group of Norwegian investigators, for example, examined the associations between frequency, duration and intensity of physical activity, and physical and mental health among 4,500 adults ranging in age from 19 to 91 (Med. Sci. Sports Exerc. 2010 Dec. 1 [Epub ahead of print]). Fifty-six percent of the participants were females, and 40% were less active than recommended by international guidelines.
The investigators analyzed the participants’ health related quality of life measured by the Short Form–8 Health Survey. Frequency and duration were assessed by items validated in HUNT (the Nord-Trøndelag Health Study), and intensity was measured by the Borg Rating of Perceived Exertion scale. The findings? Exercise at any level is associated with better physical and mental health in both genders – particularly among older people.
Another compelling study looked at the connection between physical activity and mental health among undergraduate students in the United Kingdom. In this study, 100 undergraduates completed questionnaires measuring their levels of anxiety and depression using the Hospital Anxiety and Depression Scale and their physical activity levels using the Physical Activity Questionnaire. "Significant differences were observed between the low, medium, and high exercise groups on the mental health scales, indicating better mental health for those who engage in more exercise," the investigators wrote (J. Ment. Health 2010;19:492-9).
Finally, the American Psychiatric Association’s recently updated practice guidelines for treating patients with major depressive disorder point out the benefits of exercise in improving the symptoms of mood disorders (doi:10.1176/appi.books.9780890423387.654001).
So what should we tell our patients?
Basic recommendations from the American College of Sports Medicine and the American Heart Association suggest moderately intense cardio 30 minutes a day, 5 days a week.
Aerobic exercise is clearly beneficial for mental health. However, I like to encourage walking for our patients, partly because this form of exercise is safe, flexible, and relatively inexpensive. At a pace of 3.5 miles per hour, a person could walk 2 miles in 35 minutes. This, if done every day of the week, would meet recommendations offered by the ACSM. And, of course, the benefits of exercise go far beyond promoting mental health. Exercise also reduces the risk of chronic diseases such as heart disease and type 2 diabetes (which we must monitor given ties between metabolic syndrome and some antipsychotics).
More research is needed on the benefits of exercise for those with psychiatric disability. Factors to consider are the extent of psychiatric disability and the effects of psychiatric medications that affect human physiology. Such complications could make prescribing appropriate exercise – other than walking, that is – a difficult choice. Caution: promoting daily exercise can prove injurious to the pharmaceutical industry! But that’s a topic for another time.
We must preach the benefits of exercise. Simple walking on a routine basis will lead to giant strides in mental well being.
Dr. Lamba is chief resident of psychiatry at St. Elizabeth’s Hospital, Boston.