Weight training vs. aerobic training, or both?... It's the cardiac adaptations that matter. How do various exercises affect the heart? Let's explore how weight training and endurance training shape your heart differently. Weight Training: Resistance exercise creates pressure overload, leading to CONCENTRIC hypertrophy, where the heart's walls thicken, but the chamber size remains unchanged. This enhances force generation (power) but may reduce filling efficiency if overdone without aerobic activity. This is important because it doesn't affect stroke volume or the amount you pump with each beat. Furthermore, the thickening can decrease compliance of the tissues and also lead to stiffening of the major vessels leaving the heart. Endurance Training: Aerobic exercise causes volume overload, resulting in ECCENTRIC hypertrophy, where the chamber enlarges while walls thicken slightly. This improves cardiac efficiency, lowers resting heart rate, and boosts cardiovascular health, though excessive training may have risks. More importantly... a larger chamber (to a point) increases your stroke volume. That, in turn, is a contributor to improving your VO2 max. The more blood you pump (larger stroke volume), the more oxygen can be delivered to your tissues. This is why we need to combine bone resistance and aerobic training. Weight training strengthens muscles and metabolism but lacks the heart chamber adaptations of aerobic exercise. Adding aerobic training enhances arterial health, lowers blood pressure, and boosts heart efficiency. For the best results: Weight train 2–3 times weekly. Include 150 minutes of moderate aerobic activity weekly. Your heart thrives on variety. Aerobic conditioning can balance out some of the less advantageous adaptations that resistance training brings. keep in mind... this is an orthopedist talking about the heart ;-). So take it for what it's worth