Aim. Exercise-based cardiac rehabilitation (exCR) reduces morbidity and mortality after acute coronary syndrome (ACS). Little is known about physical activity (PA) levels at exCR program completion and associated demographic, medical, and psychosocial factors.

Methods. Cross-sectional data from the ongoing Keep-Up-Going study were used, including 100 participants with recent ACS and ≥80% attendance to 3 months supervised exCR program. Physical activity was assessed by an accelerometer and self-reported psychosocial characteristics were collected at the end of the exCR. Associations between achieving the PA target (>150 min of moderate-to-vigorous-intensity PA/week) and biopsychosocial characteristics were assessed using univariable logistic regression analyses.

Results. Mean age was 67 years and 24% were women. Participants achieving the PA target (76%) were more likely to have higher levels of social support, higher outcome expectations for PA, and higher intrinsic regulation (motivation, p < .05 for all). Those not achieving the PA target (24%) had a higher proportion of sedentary time, fewer steps/day, and were more likely to be older, retired, and have reduced left ventricular ejection fraction (LVEF) (p < .05 for all).

Conclusions. Although exCR participation provides exercise routines, one-fourth of individuals did not reach the guideline-directed PA targets after an ACS. In addition to higher age and reduced LVEF, lower levels of social support, outcome expectations, and motivation were associated with low levels of PA. Exploring these factors could be of importance to support individuals’ behavior change toward increased PA during the exCR period.