Answer: physiological hypertrophy
Step-by-step explanation:
Brian's heart is facing physiological hypertrophy. It is considering the natural increase in an organ's size and that is what is happening with his heart since it revealed a slightly enlarged left ventricle.
It happened because of his aerobic exercise program two years ago and because of that program, he is going on long-distance cycling events.
Physiological hypertrophy is something that is considering the normal organization of cardiac structure.