Philosophy

Institutional Affiliation Exercise, Anxiety, and Depression
Over the years, exercise has been linked to improved moods of patients specifically anxiety and depression.  There are models developed to explain how exercise improves peoples mood.  Physiologic changes thought to be brought about by exercise are explained in the hyperthermic model and the endorphin hypothesis.  Improved moods caused by changes in the psychological state after exercise are also illustrated in models that discuss self esteem and mastery explanations and the distraction hypothesis (Daley, 2002).

Many researchers have dedicated their time and effort to finding evidences to support the thesis that exercise reduces anxiety and depression.  The type of exercise that research studies correlate with the reduction of depression and anxiety symptoms involves the use of the bodys muscular strength, flexibility, and cardiovascular endurance (Stuart  Laraia, 2005).  Providing sufficient empirical proof to this thesis will significantly benefit stakeholders of the healthcare system.  Not only will it lower the costs of treating mental health problems such as depression and anxiety, but it will also contribute to the research and development of nonpharmacologic interventions used to treat these problems.  As such, this paper aims to provide a systematic review of literature supporting the thesis that there is a relationship between exercise and a resulting reduction in anxiety and depression.

Review of Literature and Discussion
In a fact sheet released by the University of California Santa Cruz (UCSC, n.d.), they discussed how exercise leads to improvements in a persons mood and development of a sense of well-being.  They provided information based on researches on how exercise makes anxious people feel relaxed.

Supporting details include statements that both single sessions and regular exercise reduce anxiety.  Furthermore, exercise was shown to have greater beneficial effects in people clinically diagnosed with anxiety disorders.  They also provided statements that summarize research results suggesting that exercise reduces depression.  Researches showed that both aerobic and anaerobic exercises pull out a person from a depressed mood.  Likewise, exercise is shown to have an antidepressant effect on patients diagnosed with depression (UCSC, n.d.).

In a research article by Hamer, Stamatakis, and Steptoe (2009), they concluded that engaging in any physical activity for at least 20 minutes per week results in lesser risk of having pyschological distress.  In this research, they surveyed 19,842 men and women who came from the Scottish Health Survey as participants.  They measured the psychological distress of the participants through the use of the General Health Questionnaire wherein a score of 4 or more indicates psychological distress.  Measure of physical activity per week was obtained through logistic regression model calculations.  Based on their results, it was suggested that higher levels of physical activity will result in higher reduction of psychological distress (Hamer et al., 2009).

A similar study conducted by a group of doctors revealed that aerobic exercise at a dose consistent with public health recommendations is an effective treatment for MDD major depressive disorder of mild to moderate severity and a lower dose is comparable to placebo effect (Dunn, Trivedi, Kampert, Clark,  Chambliss, 2005, p. 1).  One of the four randomized groups in this study was exposed to an aerobic exercise treatment plan which used the recommended standard for physical activity while others were exposed to either a lower exercise regimen or placebo control.  Outcomes were measured through scores generated from the 17- item Hamilton Rating Scale for Depression (Dunn et al., 2005).

Numerous research studies provide data that compare the anxiety levels and depressed state of an exercise group and a no-treatment control group.  Their data suggest that the exercise groups have less anxiety and depression than the control groups.  In this line, a recent study used control and experiment groups to identify effectiveness of exercise in reducing depressive symptoms of participants aged 18 to 23 years old.  In order to compare the difference of results between groups, they used a pre-testpost-test method wherein the participants answered the Beck Depression Inventory before and after the 5-week exercise regimen.  In addition to this, they obtained saliva samples for DNA analysis.  Based on their results, it was suggested that the mechanism with which exercise produces reduction in symptoms of depression is likened to the effects of selective serotonin uptake inhibitors, a type of a pharmacologic antidepressant.  This strengthens the idea that exercise should be legitimately used for the treatment of depression (Rethorst, Landers, Nagoshi,  Ross, 2009).

In another research study, participants with symptoms of anxiety were engaged in a 2- week exercise treatment plan where outcomes were assessed prior, during, and after the exercise regimen.  Results showed that exercise reduced anxiety sensitivity which leads to alleviation of the depressed and anxious mood (Smits et al., 2008).

Some research studies also employed methods of self-report from participants regarding their physical activity and mental health through the use of questionnaires.  In a study conducted by De Moor, Beem, Stubb, Boomsma, and De Geus (2006) among families with adolescent and adult twins in Netherlands, their research findings concluded that regular exercise is associated with lower neuroticism, anxiety and depression and higher extraversion and sensation seeking in the population (p. 273).

In a prospective research study, it was concluded that there is a two-way relationship between exercise and depression.  This indicates that higher levels of physical activity reduce depression while depression reduces levels of physical activity in the future.  This implies that interventions should be directed at increasing physical activity among populations that are most at risk of developing depressive symptoms (Jerstad, Boutelle, Ness,  Stice, 2010).  A prospective research study may not be as good as a randomized clinical trial, but its yielded results are still reliable.  However, one possible limitation of this study is that participant responses may have been affected since the study was conducted over a long period of time.  Events that may affect any aspect of a persons life may also affect their response in the study such as pregnancy, death, etc.

There are also a number of research studies dedicated in providing support to the thesis by employing a method of review analysis of research articles.  In line with this, a group of researchers did a systematic review of 40 scholarly journal articles (1995- 2007) about the sedentary lifestyle of chronically ill patients.  Meta- regression analysis was employed and it was concluded that exercise reduces the symptoms of anxiety in chronically- ill patients who live a sedentary lifestyle (Herring, OConnor,  Dishman, 2010).

Another systematic review of related research articles was conducted in 2007 and 2008 which concluded that exercise reduces symptoms in clients with depression.  The group reviewed research articles which contained randomized clinical trials that observed effects of exercise on experiment and controlplacebo group.  They also suggested that more systematic reviews should be conducted to determine effect of exercise in people who manifest depression but are not clinically diagnosed with depression (Mead et al., 2008).

A Polish research article discussed meta-analyses of both experimental and correlational studies that showed reductions in anxiety and depression in both healthy and clinical patients after aerobic exercises are performed in a specific period of time.  It explained that this effect of exercise in the alleviation of moods is associated with the theories relating physiologic releases of endorphins and monoamines (Guszkowska, 2004).

Summary and Critique
There are available recent evidences that can best support the thesis that there is a connection between exercise and a resulting reduction in anxiety and depression.  The availability of methodologically sound researches and high-level evidence-based studies indicates that there are strong and reliable bases for the thesis.  This also supports the idea that research and evidence aid in the implementation of new innovative techniques in treating health problems, in this case, exercise for the reduction of anxiety and depression.

The strength of the research studies discussed is its quality of evidence base.  Two of the first five research studies cited are randomized clinical trials while the other two are quasi-experiments.  In the hierarchy of evidence-based studies, randomized clinical trials and quasi-experiments are high up in the evidence pyramid (SUNY Downstate Medical Center, 2004).  This indicates that empirical proofs to this thesis are highly recommended evidence bases.  It is commendable that their methods involved field-testing of exercise and the pretest-posttest assessment of the mental health status of the participants.  In comparison to merely asking or surveying people regarding their physical activity, engaging the participants in an actual exercise program is a better way of finding out the results.

The actual field-testing of the exercise variable increases the likelihood that people will believe the results of the research.  People learn more from lived experience rather than just theoretical learning, for example, books or journals.  Ideally, the target audience of these studies is the general population who need to be encouraged to include exercise in their daily routine because it helps reduce anxiety and depression.  Hence, studies should be able to communicate this with the larger population who do not understand scientific jargons and tend to only believe what they see or what they can relate with.  In this case, people who can testify that they actually engaged in an exercise program that resulted in their improved mood are something that the general population can relate with.  Therefore, it is easier to convince people that the health action can really lead to improved health outcomes.

The significance of a study justifies that a study is ethical to conduct.  It can be assumed that the significance of these studies focus on proving that exercise can reduce anxiety and depression for both healthy and ill people to the alleviate the conditions.  In effect, the idea of exercise as a health promoting activity to prevent anxiety and depression was also addressed in these research studies.  This is a good outcome of the researches because at present, efforts are pushed toward health promotion and disease prevention instead of waiting for the disease before treating it.  Though there are still arguments and conflicts among researchers about the legitimacy of exercise in reducing anxiety and depression, this new theory about exercise already encourages people in engaging in a healthy habit.

Based on the studies discussed, one common potential limitation of these research studies is patient-response bias in answering the self-report questionnaires used to assess the mental health status of the participants.  This is due to the possibility that patients may not truly reflect their personality or behaviors in the questionnaires.  They may choose an answer that reflects what they want themselves to be or to do rather than what they are doing in reality.  Nevertheless, it must be remembered that these tools are valid and has high sensitivity to screening depression (Lincoln, Nicholl, Flannanghan, 2003).  Hence, this limitation is only part and partial of the overall studies.

Another potential limitation is the representativeness of the number of samples used in these research studies.  Getting a large number of participants in a research study is very difficult.  Hence, most research studies use a small number of samples to generate data from.  This makes it difficult to apply to the general population the conclusions drawn from the studies.  This is one possible aspect in researches that needs improvement.  In order to have legitimate and reliable claims, data should not only produce good statistical data regarding the variables involved but also present a large proportion of the population to whom the study was conducted.

Some of the research evidences also mentioned include systematic reviews and meta-analyses.  These are ways to determine the quality use of the best current evidence and these two are the topmost in the evidence pyramid (SUNY Downstate Medical Center, 2004).  It is good to know that recent systematic reviews suggested and supported the thesis that exercise reduces symptoms of anxiety and depression.  This strengthens the stance that there is an existing relationship between exercise and a resulting improved mood.  This is also an indicator that previous researches provide sufficient support to this thesis.  However, a possible limitation that should be considered here is selection bias of research articles included in the systematic review.  It is best to increase the number of researches reviewed in proportion to all recent research articles published regarding this thesis in order to eliminate selection bias.

The researches discussed contribute in building a more convincing assertion for the thesis.  They may have their own scope and limitations but a combination of previous and recent researches lead to a stronger foundation for theories that are not yet scientifically proven.