Cooney et al. (2013) completed a systematic review which concluded that exercise was more effective in comparison to no treatment, or a comparator controlled intervention.
Yet, this systematic review (Cooney et al, 2013) also found that exercise was not more effective than psychological or pharmacological therapies at reducing symptoms of depression.
This review highlights the argument that it would be worthwhile for more researchers to look into which specific forms of exercise are most effective at limiting symptoms of depression (Cooney et al, 2013).
It would also be beneficial to understand exactly how many sessions of particular types of exercise are needed to prevent depression, and how long each of these sessions should take or continue for (Cooney et al, 2013).
A systematic review examining interventions to reduce sick-days in workplaces by Neiuwenhuijsen et al (2014) also explored the mental health benefits of physical activity.
The review found in one particular study that the number of participants taking sick-leave days from work reduced when participants performed strength exercises.
A further two more studies indicated that more aerobic exercises on the other hand, such as running, were no more effective than regular relaxation and stretching (Neiuwenhuijsen et al, 2014).
Meekums, Karkou and Nelson (2015) conducted a review into the use of exercise in the form of dance movement therapy to treat depression, however they concluded that its effectiveness could not definitively be measured yet as studies were only conducted with quite small numbers.
Cramer et al (2017) interestingly could conclude that yoga was an effective form of exercise for reducing depression. This specific finding was in comparison to psychosocial or educational interventions.
Additionally, yoga (as per evidence of moderate quality), was shown to have the benefits of (Cramer et al, 2017):
Another systematic review outlined the need for increased research, particularly to focus on implementing non-pharmacological interventions for people with traumatic brain injury (TBI) who also have clinical depression (Gertler, Tate & Cameron, 2015).
Higher quality evidence is necessary in order to understand whether exercise and other non-pharmacological interventions are effective at preventing depression for people with TBI and clinical depression (Gertler et al, 2015).
Another study looking at the relationship between mental wellbeing and exercise, was that of Kendrick et al (2014).
Their systematic review concluded that whilst exercise interventions may help to lessen the fear of falls for older community-dwelling participants, immediately post-intervention, there is not sufficient evidence to conclude that this fear is reduced long term.
Evidently, this study was not specifically focused on depression and a conclusion cannot be made regarding whether exercise interventions’ immediate falls-related-fear-reduction is subsequently able to prevent dementia.
Similarly, another study touched on exercise and depression but it was focused on chronic fatigue syndrome (Larun et al, 2017). Larun et al (2017) found that exercise could lessen fatigue. Yet, the study did not conclude whether it could prevent depression (Larun et al, 2017).
From this overview of studies, it is apparent that exercise may show some promise in reducing depressive symptoms.
Conversely, further research is necessary to establish best-practice guidelines for which specific types of exercise are most effective in treating depression or specific depressive symptoms.
It is also clear that additional research is needed to generate best-practice guidelines for preventing depression via the development of exercise plans that outline the amount of exercise needed, and the timeframe or exercise duration.
Of course, it is also apparent from this literature overview that there is a need for more high-quality evidence. This may require careful consideration of adequate sample sizes, how to reduce bias, and how to provide thorough details of the exercises utilised.