The STRENGTH Study: A cluster randomised controlled trial of the effect of a behaviour change intervention added to cardiac rehabilitation on physical activity adherence.

No significant differences in daily minutes of moderate-to-vigorous physical activity (MVPA) or steps per day were observed between intervention and control groups at six months follow-up.

• Primary outcome was physical activity measured with an ActiGraph GT3X+ accelerometer
• The trial was a cluster randomised controlled trial across six community-based maintenance stage cardiac rehabilitation classes
• Total of 96 participants were enrolled (mean age 65.04 ± 8.38 years; 75% male)
• No significant differences were found between the behaviour change intervention group and standard care group at six months

No significant differences in secondary outcomes including self-rated health, quality of life, and mental wellbeing were observed between groups at six months follow-up.

• Secondary outcomes assessed included self-rated health, quality of life, and mental wellbeing
• Neither group showed superiority on any secondary outcome measure
• Findings were consistent across all secondary outcome domains

The study was conducted as a cluster randomised controlled trial across six community-based maintenance stage cardiac rehabilitation classes.

• Six clusters (community-based maintenance stage cardiac rehabilitation classes) were randomised
• 96 participants total were included
• Participants were in the maintenance stage of cardiac rehabilitation, representing a later phase of rehabilitation
• The trial was registered at ClinicalTrials.gov NCT05705310

High baseline physical activity levels among participants and extended cardiac rehabilitation support provided to both groups may have masked any intervention effects.

• Authors attributed null findings partly to high baseline physical activity levels among participants
• Both intervention and control groups received ongoing cardiac rehabilitation support throughout the study period
• The extended support to both groups was identified as potentially masking intervention-specific effects
• Authors noted that continued access to cardiac rehabilitation sustained high physical activity levels in both groups

Continued access to cardiac rehabilitation sustained high physical activity levels regardless of the additional behaviour change intervention.

• Both groups maintained high physical activity levels over the study period
• This suggests that ongoing cardiac rehabilitation participation itself is associated with sustained physical activity
• Authors recommended future research to disentangle the independent effects of behaviour interventions and ongoing cardiac rehabilitation support

Coronary heart disease is identified as the leading cause of global mortality, with cardiac rehabilitation including physical activity shown to reduce related morbidity and mortality.

• Coronary heart disease imposes significant health and economic burdens globally
• Cardiac rehabilitation including physical activity can reduce coronary heart disease-related morbidity and mortality
• The study was designed to test whether adding a behaviour change intervention to cardiac rehabilitation could promote and maintain physical activity beyond standard care timeframes