A systematic review of behaviour change techniques employed in interventions aimed to change physical activity behaviour in autistic individuals

Background
Autistic individuals experience disproportionately poor physical and mental health outcomes, many of which can be mitigated through lifestyle modification such as increasing levels of physical activity. While behaviour change interventions hold promise in promoting physical activity, their effectiveness in autistic populations remains underexplored, particularly in relation to theoretical foundations and intervention content.

Objective
To systematically review behaviour change techniques applied to physical activity interventions for autistic individuals, evaluate application of psychological theory, and adaptations made for autism.

Methods
A systematic search of five databases was conducted in accordance with PRISMA guidelines. Eligible studies were intervention-based, targeted physical activity behaviour as a primary outcome, and included autistic participants. Data were narratively synthesised, and intervention components were coded using the Behaviour Change Taxonomy (BCTTv1). Intervention efficacy was evaluated using a ‘promise ratio’ and statistical comparisons were conducted to assess associations between intervention promise, Behaviour Change Techniques, theory use, and autism-specific adaptations.

Results
Thirty-three studies were included (n=26 child-focused; n=7 adult-focused). Eleven studies reported explicit use of behaviour change theory, with no significant association between theory use and intervention promise. A total of 266 BCTs were coded; most frequently used was instruction on how to perform the behaviour, though not associated with efficacy. In adults, promising techniques included goal setting and behavioural rehearsal; in children, demonstration and reinforcement were effective. Autism-specific adaptations were significantly associated with intervention promise and included sensory considerations and structured environments.

Conclusions
Theory-informed, autism-adapted interventions show potential for promoting physical activity in autistic populations. Future research should prioritise high-quality designs, meaningful involvement of autistic individuals, and rigorous application of behavioural theory.