Final answer:
Aerobic exercise results in the heart adapting through increased stroke volume and lower resting heart rate, along with increased size and mass, leading to a more efficient and powerful cardiac muscle.
Step-by-step explanation:
The cardiac hypertrophy adaptations of aerobic exercise include a number of physiological changes, such as increased stroke volume and a lower resting heart rate. With regular aerobic exercise, the heart's muscles adapt and become more efficient at pumping blood. This adaptation results in a heart that can pump a greater volume of blood with each beat (increased stroke volume) and a reduced need to beat as frequently (lower resting heart rate). Additionally, the size and mass of the heart can increase, which leads to the heart becoming stronger and more efficient at pumping blood.
Moreover, during intense physical activity, a healthy young adult's cardiac output (which is a product of heart rate and stroke volume) can increase significantly. It is also noteworthy that with an increase in heart rate above 160 bpm, the cardiac output can continue to increase, but this is generally tied to the individual's fitness level and the heart's capacity to maintain efficiency with higher rates.