Cardiac hypertrophy is characterized by what?

Cardiac hypertrophy is characterized by the enlargement of the heart, specifically an increase in the size of the cardiac muscle cells. This adaptation often occurs in response to increased workload, such as from regular intense exercise or from conditions like hypertension. In athletes, this can result from the demands of their training and is generally considered a healthy adaptation of the heart to improve its efficiency and capability to pump blood.

The other options do not accurately describe cardiac hypertrophy. An increase in blood volume may occur as a result of improved cardiovascular fitness but is not synonymous with cardiac hypertrophy itself. Similarly, a decrease in heart rate can be a benefit of improved cardiovascular fitness, but it does not define or characterize hypertrophy. Strengthening of heart valves is unrelated to cardiac hypertrophy, as this condition specifically involves the muscle tissue of the heart rather than the structural integrity of the valves.