A group motivational intervention to support motivation for physical activity among adults in residential treatment for substance use disorders: a series of N-of-1 studies

Objective: Physical activity (PA) may offer health benefits for individuals undergoing substance use disorder (SUD) treatment, yet relapse, comorbidities, and motivational challenges often hinder PA maintenance. This study assessed the impact of a motivational intervention aimed at increasing PA motivation and maintenance in a residential SUD treatment setting. 

Methods and Measures: This non-concurrent multiple-baseline N-of-1 study consisted of a six-week baseline and a ten-week intervention period. The study was conducted with 17 participants from a male-only residential SUD treatment facility in Perth, Australia. Seven participants provided sufficient data for statistical analysis. Participants received ten weekly sessions of a motivational face-to-face intervention. Daily data on PA motivation, substance use cravings, and affect were collected through ecological momentary assessments. Non-overlap methods and randomisation tests, and piecewise regression analyses were employed to assess changes in all variables between study phases. 

Results: No changes in PA were observed across study phases. However, measures of affect improved, and self-reported craving decreased over time. Notably, the intervention enhanced autonomous motivation in some participants, although its effects on controlled motivation were mixed. 

Conclusion: These findings suggest that the motivational intervention may enhance autonomous motivation. Future studies should involve larger samples and diverse SUD treatment settings.