acute and chronic depression. It is hoped that the infor-
mation provided will be valuable not only to physicians,
exercise psychologists and physiologists, but also to those
interested in personal or public health, politics and
A comprehensive search in PubMed and Science Direct
was conducted using MeSH terms that are germane to
acute and chronic depression (e.g., depression symptoms,
mood, depressive disorder, psychotherapy) in conjunction
with exercise and psychophysical mechanisms (e.g.,
exercise, physical activity, b-endorphin, opioids, seroto-
nin, pituitary gland). The search also included the articles
cited in the identiﬁed papers. All articles resulting from
the above methods were considered in this review, and
only those deemed irrelevant (i.e., not directly studying
the effects of exercise and physical activity on depres-
sion) were omitted. The following pages cover informa-
tion regarding exercise and physical activity as
treatments for depression, the endorphin hypothesis and
the hormonal effects of b-endorphins on depression, the
effects and the required frequency and mode of exercise
and physical activity on depression, as well as the
inﬂuence of an individual’s age on the successfulness
of exercise and physical activity interventions for
Deﬁnition, classiﬁcation criteria and treatment
Depression represents a major illness with both health and
social consequences similar to chronic diseases such as
diabetes, congestive heart failure and hypertension .
According to the World Health Organization, depressionis
an illness characterized by negative mood, decreased
interest for pleasure, feelings of guilt, uneasy sleep,
decreased appetite and energy, as well as poorbrain con-
centration [1,2]. These feelings can be either acute or
chronic, resulting in a reduced interest for life which can
lead to extreme actions such as suicide . The criteria
based on which classiﬁcation of depression is accom-
plished are appointed by the International Classiﬁcation of
Diseases (ICD-10) for worldwide use  and the Diag-
nostic and Statistical Manual of Mental Disorders (DSM-
IV) developed in the United States . Generally, these
standardized criteria are used to separate ‘‘normal’’
depressed mood caused, for instance, by disappointment,
from depressive disorders also known as ‘‘affective disor-
ders’’ and ‘‘mood disorders’’ [8,9].
Depression is normally treated with various pharma-
ceutical agents or psychotherapeutic interventions or a
combination of these. Current evidence shows that patients
seeing a primary care provider are more likely to have a
failed treatment than patients seeing a psychiatrist .
This, however, does not suggest that pharmacological
agents are unsuccessful in the treatment of depression.
Indeed, a large number of studies show that different
pharmacological treatments are successful in treating acute
depressive episodes . In this light, a successful cooper-
ation between primary and specialty mental health sectors
is crucial, since most patients with depression ﬁrst seek
help in primary care [11–13]. Therefore, consultative roles
for mental health specialists have been recommended in
some countries to support primary care physicians in the
treatment of depression [14,15]. Relatively, recent evi-
dence suggests that an exercise science specialist may also
need to complement the primary care physicians and
mental health specialists in order to successfully tackle
depression symptoms and episodes . For instance, it is
widely accepted that mood states are highly depended on
endorphin secretion . Moreover, according to the
endorphins hypothesis, exercise augments endorphin
secretion which, in turn, reduces anxiety and depression
levels . These notions are further discussed in the fol-
b-Endorphin and exercise
Endorphins are endogenous opioid polypeptide compounds
produced by the pituitary gland and the hypothalamus in
vertebrates during strenuous exercise, excitement, pain,
and they resemble the opiates in their abilities to produce
analgesia and a sense of well-being . The opioid system
plays a key role in mediating analgesia and social attach-
ment and may also affect depression given the link between
b-endorphins and depression symptoms [18–20]. To date,
b-endorphin secretion has been used for the diagnosis of
depression and it could be used as an agent in a therapeutic
strategy . Moreover, available data have shown that the
l-opioidergic system is considerably involved in the eti-
ology of mental disorders, thus providing a rationale for the
use of l-opioid ligands such as b-endorphin in behavioral
therapies . A recent meta-analysis concluded that the
mechanisms by which exercise may improve depression
remain uncertain mainly due to methodological limitations
of existing research . Yet, based on recent biological
evidence linking the opioid system with mood and
depression [16,19,23], it seems reasonable to explore a
relevant hypothesis that has received considerable atten-
tion. According to the ‘endorphins hypothesis’, exercise
augments the secretion of endogenous opioid peptides in
A landmark study led by the Black Dog Institute has revealed that regular exercise of any intensity can prevent future depression -- and just one hour can help.
Published in the American Journal of Psychiatry, the results show even small amounts of exercise can protect against depression, with mental health benefits seen regardless of age or gender.
In the largest and most extensive study of its kind, the analysis involved 33,908 Norwegian adults who had their levels of exercise and symptoms of depression and anxiety monitored over 11 years.
The international research team found that 12 percent of cases of depression could have been prevented if participants undertook just one hour of physical activity each week.
"We've known for some time that exercise has a role to play in treating symptoms of depression, but this is the first time we have been able to quantify the preventative potential of physical activity in terms of reducing future levels of depression," said lead author Associate Professor Samuel Harvey from Black Dog Institute and UNSW.
"These findings are exciting because they show that even relatively small amounts of exercise -- from one hour per week -- can deliver significant protection against depression.
"We are still trying to determine exactly why exercise can have this protective effect, but we believe it is from the combined impact of the various physical and social benefits of physical activity.
"These results highlight the great potential to integrate exercise into individual mental health plans and broader public health campaigns. If we can find ways to increase the population's level of physical activity even by a small amount, then this is likely to bring substantial physical and mental health benefits."
The findings follow the Black Dog Institute's recent Exercise Your Mood campaign, which ran throughout September and encouraged Australians to improve their physical and mental wellbeing through exercise.
Researchers used data from the Health Study of Nord-Trøndelag County (HUNT study) -- one of the largest and most comprehensive population-based health surveys ever undertaken -- which was conducted between January 1984 and June 1997.
A healthy cohort of participants was asked at baseline to report the frequency of exercise they participated in and at what intensity: without becoming breathless or sweating, becoming breathless and sweating, or exhausting themselves. At follow-up stage, they completed a self-report questionnaire (the Hospital Anxiety and Depression Scale) to indicate any emerging anxiety or depression.
The research team also accounted for variables which might impact the association between exercise and common mental illness. These include socio-economic and demographic factors, substance use, body mass index, new onset physical illness and perceived social support.
Results showed that people who reported doing no exercise at all at baseline had a 44% increased chance of developing depression compared to those who were exercising one to two hours a week.
However, these benefits did not carry through to protecting against anxiety, with no association identified between level and intensity of exercise and the chances of developing the disorder.
According to the Australian Health Survey, 20 percent of Australian adults do not undertake any regular physical activity, and more than a third spend less than 1.5 hours per week being physically active. At the same time, around 1 million Australians have depression, with one in five Australians aged 16-85 experiencing a mental illness in any year.
"Most of the mental health benefits of exercise are realised within the first hour undertaken each week," said Associate Professor Harvey.
"With sedentary lifestyles becoming the norm worldwide, and rates of depression growing, these results are particularly pertinent as they highlight that even small lifestyle changes can reap significant mental health benefits."
Materials provided by University of New South Wales. Note: Content may be edited for style and length.
- Samuel B. Harvey, Simon Øverland, Stephani L. Hatch, Simon Wessely, Arnstein Mykletun, Matthew Hotopf. Exercise and the Prevention of Depression: Results of the HUNT Cohort Study. American Journal of Psychiatry, 2017; appi.ajp.2017.1 DOI: 10.1176/appi.ajp.2017.16111223
Cite This Page:
University of New South Wales. "One hour of exercise a week can prevent depression." ScienceDaily. ScienceDaily, 3 October 2017. <www.sciencedaily.com/releases/2017/10/171003093953.htm>.
University of New South Wales. (2017, October 3). One hour of exercise a week can prevent depression. ScienceDaily. Retrieved March 14, 2018 from www.sciencedaily.com/releases/2017/10/171003093953.htm
University of New South Wales. "One hour of exercise a week can prevent depression." ScienceDaily. www.sciencedaily.com/releases/2017/10/171003093953.htm (accessed March 14, 2018).