Athlete's heart and cardiovascular care of the athlete: scientific and clinical update.

“The physiologic capabilities of the heart are enormous, and in judging the effect of any undue exertion on it, we must not regard the murmurs of the irregularity alone, but must also consider carefully, the way in which the heart is doing its work, its strength, as shown by its ability to maintain proper arterial tension, and its recuperative power. As with other muscles, not size but quality tells in the long run.”1 —Eugene Darling