Medical Student University of Saskatchewan College of Medicine Regina, Saskatchewan, Canada
Background: Exercise confers many health benefits and is associated with reduced all-cause and cardiovascular (CV) mortality. Paradoxically, some evidence indicates that high-volume endurance exercise may increase coronary artery calcium (CAC) scores, a robust predictor of coronary artery disease and CV events. This systematic review aimed to assess the relationship between exercise training volume and CAC scores.
METHODS AND RESULTS: We searched Medline, EMBASE, PubMed, and Cochrane Library (from 1990 to October 2024) and reviewed references of the relevant literature and included articles. Studies were included if they reported quantified exercise volume and CAC scores. The methodological index for non-randomized studies (MINORS) scale was implemented to test study quality. We stratified exercise volume (min/wk) into four categories: low ( < 150 min/wk), moderate (150-300 min/wk), moderate-high (300-450 min/wk), and high (>450 min/wk). To convert studies reporting exercise in MET-min/wk or km/wk into min/wk, exercise intensity was assumed to be 10.5 METs with a corresponding running pace of 10.8km/h, based on the 2024 Compendium of Physical Activities. Of the 28 studies meeting inclusion criteria, 14 reported higher CAC scores in their highest-volume exercise groups, six found no association or an inverse association, and eight were single-cohort studies. All six comparative studies involving participants with >450min/wk of exercise found higher CAC scores among their high-volume exercise cohorts. Among the seven studies reporting mortality or CV events, six reported no relationship or an inverse association between exercise volume and these endpoints. Finally, multiple studies reported a more benign, calcified plaque composition among their high-volume exercisers, representing a potential mechanism for the lower risk of CV events and mortality reported in this population compared to less active individuals with similar CAC scores.
Conclusion: Our systematic review suggests high-volume exercisers may have higher CAC scores than less active cohorts. However, lower mortality and CV event rates observed in these populations question the clinical significance of this observation. Among high-volume exercisers, increasing CAC scores may indicate plaque stabilization rather than denovo formation of atherosclerotic plaques and/or plaque progression. More research is required to understand the clinical implications of elevated CAC scores in high-volume exercisers.
