Current evidence of the effects of exercise on depression outcomes among adults suggests that whilst the quality of investigations into exercise as a treatment needs to be improved, the prescription of exercise as a treatment for depression is appropriate when combined with other treatments (Daley, 2008). A recent review of the use of exercise in the prevention and treatment of adolescent depression concluded that MDD is common among adolescents, however clinical trials utilising exercise as an intervention undertaken in this age group are limited, with the majority suffering from a lack of methodological rigour (Dunn & Weintraub, 2008; Purcell et al, 2010). The major limitations suggested of previous work into the efficacy of exercise intervention for the treatment of MDD among adolescents are: 1. A lack of clinical diagnosis of MDD and symptom severity, with limited repeat assessment of MDD and severity to ensure reliability and validity of diagnosis throughout the study. 2. A lack of clear definition regarding exercise intervention, including frequency, intensity, time and type, and whether the intervention was used as monotherapy, in combination with another therapy, or to augment another therapy. 3. A lack of appropriate outcome measures for the phase of treatment being investigated, with limited investigation of remission as the primary outcome, and additionally, a lack of assessment of social functioning (school, behaviour and relationships) as a secondary measure. With the clear need to address the efficacy of exercise intervention in the treatment of adolescent MDD, a well designed clinical trial addressing the limitations of the current body of knowledge is warranted.
There has been considerable research into the use of exercise for the treatment of depression in adults, however the majority of research in adolescent major depressive disorder (MDD) over the past decade has focused on the efficacy of medications and cognitive behaviour therapy (CBT), with these methods only achieving rates of remission of 30% to 40% and high rates of relapse among those responding positively (Kennard et al., 2006).