Physical Activity Program for TRD

Inclusion criteria

• Sedentary adults (engage in less than 60 minutes of moderate-to-vigorous PA per week) between the ages of 18 and 65 years, inclusive, capable of giving informed consent.
• Participants meeting diagnostic criteria for major depressive disorder without psychotic symptoms according to the Diagnostic and Statistical Manual of Mental Disorders - 5th Ed. and currently experiencing a major depressive episode (MDE) as confirmed by the Mini International Neuropsychiatric Interview (MINI).
• A Montgomery-Åsberg Depression Rating Scale total score of ≥ 7 at screening (mild-to-severe MDE).
• Failure of at least two trials of antidepressant therapy of adequate dose and duration during the current episode as established by the Antidepressant Treatment History Form and self-report.
• Receiving treatments congruent with Canadian Network for Mood and Anxiety Treatments guidelines with no changes to treatments one month before screening (28 days).

Exclusion criteria

• Current symptoms of mania, hypomania, mixed episodes, or psychosis.
• Have received a diagnosis of alcohol or a substance use disorder within the past 3 months or as confirmed by the MINI. Other secondary psychiatric comorbidities (e.g., anxiety disorders, trauma-related disorders, etc.) will not be excluded.
• Pregnant females.
• Acute risk for a cardiovascular event (i.e., cardiovascular event in the past within the past 12 months).
• Have any medical contraindications to exercise according to the Physical Activity Readiness Questionnaire.
• Self-reported balance, gait, or locomotion difficulties that would preclude participation in a PA program.
• Have any other condition that, in the opinion of the investigator(s), would adversely affect the subject's ability to complete the study or its measures.
• Have exercise-induced asthma.
• Taking medication that interferes with heart rate response to exercise, such as beta blockers.
• Do not own a smartphone.
• Do not have reliable access to the Internet.
• Have previously received intravenous ketamine treatment in the last 2 months.
• Non-English-speaking individuals are excluded because the ability to communicate study information, answer questions accurately and completely about the study, and obtain consent are necessary.