The research study compares the substance abuse treatment outcomes (e.g., craving, withdrawal symptoms, rates of use, abstinence) of standard intensive outpatient care, with or without an added 6-wk aerobic exercise component. In addition, certain biomarkers associated with both exercise and substance use (e.g., endocannabinoids and cortisol) will be assessed. In a rolling admissions format over the course of a year, approximately 36 treatment-seeking substance users who are currently receiving Intensive Outpatient Treatment through a local Alcohol or Other Drug Abuse agency will be randomized to either receive 6 weeks aerobic exercise training in addition to standard care or standard care with 6 weekly laboratory visits to complete questionnaires (18 per group).

Inclusion Criteria:

• Intact cognitive status and ability to provide informed consent
• ability to read and write in English sufficient to provide consent and complete study questionnaires
• current diagnosis of a single or of multiple substance use disorders
• currently enrolled in an Intensive Outpatient Treatment substance use program
• desire to quit and to seek treatment for substance use
• currently sedentary, not participating in any formal/structured exercise program

Exclusion Criteria:

• a history or present diagnosis of severe depression, psychotic, or bipolar disorder
• presence of cardiac disease or any other medical condition that would make engaging in exercise unsafe
• Undergoing methadone treatment
• chronic conditions such as cancer, diabetes, kidney disease, or autoimmune disorders
• women who are pregnant or planning to become pregnant