Influence of exercise self-efficacy on physical activity among psychologically distressed patients undergoing cardiac rehabilitation: secondary data analysis of a randomized controlled trial

Background: Cardiac rehabilitation programs are commonly employed to address modifiable lifestyle factors, such as physical inactivity. However, adherence to exercise recommendations following these interventions remains suboptimal. Psychological burdens can further impede patients’ ability to exercise. Aim: The aim of this study was to investigate the role of exercise self-efficacy (ESE) in influencing physical activity among psychologically distressed patients in cardiac rehabilitation. Methods: Data from a randomized controlled trial involving 305 participants who completed a four-week cardiac rehabilitation program were analyzed. ESE was measured using the Exercise Self-Efficacy Scale, while physical activity was assessed by aggregating the duration and frequency of up to three weekly activity types participants engaged in. Correlation analyses were conducted to examine the relationships between ESE and potential explanatory variables. A linear regression model was employed to assess the predictive role of baseline ESE on physical activity at the 3-month follow-up. Changes in ESE and physical activity over time were analyzed using paired t-tests and a mixed-effects model. Results: At the start of rehabilitation, weekly physical activity averaged 108 min, while ESE reached a mean of 28.2 points. Baseline ESE significantly predicted physical activity at the 3-month follow-up when controlling for baseline activity (b = 0.10, p = 0.006). T-tests showed a 1.75-point increase in ESE (p < 0.001) and a 68.23-minute increase in physical activity (p < 0.001) over time. Mixed-effects regression analysis indicated that each one-point increase in ESE was associated with a 12.88-minute increase in physical activity at follow-up (p < 0.001). Conclusion: ESE may have a considerable impact on physical activity among psychologically distressed patients in cardiac rehabilitation and should therefore be considered as a relevant outcome parameter when designing new intervention components. For clinical practice, these findings support the integration of routine screening for ESE upon rehabilitation entry as well as the incorporation of targeted strategies to enhance self-efficacy within cardiac rehabilitation programs. Trial registration: German Clinical Trials Register (DRKS00029295, June 21, 2022).