Analysis of 15 randomized controlled trials involving 559 sedentary individuals reveals exercise training significantly reverses the "sedentary cardiac phenotype" — a constellation of cardiac atrophy, myocardial stiffening, and altered blood flow patterns common in inactive, obesity-prone populations. Exercise interventions improved resting heart rate, systolic blood pressure, stroke volume, and left ventricular ejection fraction. Notably, high-intensity interval training proved most effective for improving diastolic function and cardiac mass, while aerobic exercise excelled at blood pressure reduction. The analysis demonstrates exercise triggers physiological adaptations resembling an "athlete's heart" — beneficial cardiac enlargement and improved pumping efficiency. Crucially, these cardiac improvements occurred independent of weight loss, suggesting exercise's direct cardiovascular benefits transcend its metabolic effects. This finding challenges the conventional focus on weight reduction as the primary pathway to cardiac health in obese individuals. The research provides compelling evidence that structured exercise can reverse years of sedentary-induced cardiac deterioration. However, as this remains a preprint awaiting peer review, these findings require validation before clinical application. The meta-analysis represents confirmatory evidence strengthening the case for exercise as medicine, particularly for cardiovascular rehabilitation in sedentary populations facing the growing epidemic of physical inactivity.