Self-reported physical activity in a randomized study from Norwegian Healthy Life Centres.

AIM: This study examines firstly if participation in a three-month intervention at Norwegian Healthy Life Centres (HLCs) improved self-reported physical activity (SR-PA), and secondly to what extent physical activity (PA) status at six months and changes from baseline were associated with demographic and motivational predictors. BACKGROUND: Regular PA is promoted as a central component of public health initiatives aimed at preventing noncommunicable diseases. METHODS: This randomized controlled trial included 118 participants (57 in the intervention group) recruited from HLCs in South-western Norway. The intervention effect was assessed by comparing the intervention group with the waiting-list control group after six months. We examined sociodemographic and motivational predictors of change combining both groups into a single cohort. This trial was registered at ClinicalTrials.gov (ID: NCT02247219). FINDINGS: At six-month follow-up, participants in the intervention group reported higher levels of SR-PA compared with the control group. The estimated effect was modest (B = 0.26, 95% CI -0.01 to 0.53), equivalent to ≈0.37 SD. Although the confidence interval included zero, the estimate remained compatible with a modest positive effect. Autonomous motivation and social support were positively associated with SR-PA after 6 months, while psychological defiance showed a negative association. Autonomous motivation and psychological defiance impacted PA change during the 6-month period in opposite directions.