Changes in self-determined motivation for exercise in people with mental illness participating in a community-based exercise service in Australia

Exercise has diverse benefits for physical and mental health in people with mental illness; however, it is unclear how to effectively promote exercise motivation in this group. The aim of this study is to evaluate the effectiveness of interventions utilising exercise instruction or behavioural counselling with people with mental illness to improve self-determined motivation for exercise, and physical and mental health. Participants were adults (aged 18+ years) receiving mental health services. Participants could choose from two 8-week programs comprising weekly group-based sessions delivered by an exercise physiologist: (a) exercise instruction in a gym (GYM) or (b) behavioural counselling (MOT). Self-determined motivation was measured using the Behaviour Regulations for Exercise Questionnaire (BREQ3). Physical health indicators included waist circumference, blood pressure, leg strength (sit-to-stand test), physical capacity (six-minute walk test) and self-reported exercise. Mental health was assessed using the Kessler-6 scale of psychological distress. Most of the 95 participants chose exercise instruction (GYM = 60; MOT = 35). At baseline, participants who chose MOT had higher external motivation, body mass index, waist circumference and psychological distress, and a higher proportion had multiple physical comorbidities than those who chose GYM. More self-determined motivation was associated with meeting physical activity guidelines. Post-intervention, GYM participants had significant improvements in self-determined motivation, psychological distress and sit-to-stand test; MOT participants had significant improvements in integrated regulation, self-reported exercise and physical functioning. In conclusion, exercise instruction can improve self-determined motivation; however, more intensive behavioural counselling support may be needed to improve self-determined motivation. Counselling programs can increase exercise behaviour and may appeal more to people with poorer health and more external motivation. Findings have high ecological validity and applicability to real-world implementation of exercise interventions. To accommodate people with diverse conditions and motivations, motivational counselling should be combined with practical exercise support, and participants afforded the autonomy to decide their level of involvement.