Exercise-Induced Cardiac Remodeling

If we could give every individual the right amount of nourishment and exercise, not too little and not too much, we will have found the safest way to health. u003e u003e -Hippocrates of Kos c.460–c.370 BC Exercise is the most effective therapy one can prescribe for good health and longevity. relatively modest doses, regular exercise reduces cardiovascular mortality by 35% and all-cause mortality by 33%.1 However, the effect of high-intensity and high-volume exercise prolonged over decades has been the subject of close scrutiny in recent years. Although some studies suggest that beyond an optimal dose, exercise follows a law of diminishing returns with a plateau of survival despite increasing investment,2,3 other studies suggest a U-shaped relationship with harm at both ends of the spectrum.4,5See Article by Weiner et al In health, the resting cardiac output is ≈5 L/min and capable of increasing to 25 to 35 L/min during strenuous aerobic exercise. This increase in cardiac output and muscle performance is facilitated by a symphony of changes in cellular respiration, ventilatory gas exchange, vascular resistance, neurohumoral transmission, and adrenergic stimulation, supporting and enhancing the necessary energy transformations. Repeated bouts of high-intensity and high-volume exercise demand that the myocardium and cardiovascular system remodel and adapt to meet the performance requirements placed on them.Cross-sectional studies of endurance athletes demonstrate that left ventricular wall thickness is 15% to 20% greater than in sedentary controls, and left ventricular cavity dimensions are 10% larger.6 The right ventricle is also enlarged, with elite athletes demonstrating 10% increases in right ventricular dimensions.7 These structural changes are beneficial and serve to equip the athlete with the necessary biological endowments to compete.However, the precise effects of long-term exercise on the heart and cardiovascular system remain incompletely elucidated. One of …