Endurance training typically increases stroke volume due to which mechanisms?

Endurance training typically increases stroke volume due to which mechanisms?

• A. Increased preload from plasma volume expansion, enhanced myocardial contractility, and lower heart rate at submaximal workloads; LV remodeling.
• B. Decreased preload and contractility, higher heart rate.
• C. No change in LV remodeling.
• D. Increased afterload.

Answer: (A)

Endurance training increases stroke volume by increasing preload, improving contractile efficiency, and enlarging the heart’s pumping chamber. Plasma volume expands with endurance training, which raises venous return and left ventricular end-diastolic volume. The ventricle fills more during diastole, and this greater stretch boosts stroke volume via the Frank–Starling mechanism. In addition, the heart adapts with enhanced contractility, allowing a stronger squeeze and more complete ventricular emptying. Structural remodeling further supports this: the left ventricle enlarges its chamber (eccentric remodeling), increasing filling capacity and stroke volume at rest and during submaximal work. The tendency for a lower heart rate at submaximal workloads also helps maintain longer filling times, contributing to a higher stroke volume overall.

Endurance training increases stroke volume by increasing preload, improving contractile efficiency, and enlarging the heart’s pumping chamber. Plasma volume expands with endurance training, which raises venous return and left ventricular end-diastolic volume. The ventricle fills more during diastole, and this greater stretch boosts stroke volume via the Frank–Starling mechanism. In addition, the heart adapts with enhanced contractility, allowing a stronger squeeze and more complete ventricular emptying. Structural remodeling further supports this: the left ventricle enlarges its chamber (eccentric remodeling), increasing filling capacity and stroke volume at rest and during submaximal work. The tendency for a lower heart rate at submaximal workloads also helps maintain longer filling times, contributing to a higher stroke volume overall.