Abstract
The structural adaptations of the "athlete's heart" include left atrial (LA) enlargement. A literature search was performed based on PubMed listings up to November 2, 2019 using "athletes AND left atrium," "athletes AND LA," "sports AND left atrium," "sports AND LA," "exercise AND left atrium," and "exercise AND LA" as the search terms. Eligible studies included those reporting the influence of demographic, anthropometric and athletic characteristics on LA size in athletes. A total of 58 studies were included in this review article. Although LA volume has been reported to be greater in males compared to females when indexed for body surface area (BSA), there was no difference between sexes. The positive association between LA size and age in athletes may reflect the increase in body size with maturation in nonadult athletes and the training age of endurance athletic activity in adult athletes. Caucasian and black athletes have been demonstrated to exhibit similar LA enlargement. The positive association of LA size with lean body mass (LBM) possibly accounts for the relationship of LA size with BSA. LA enlargement has been reported only in endurance-trained, but not in strength-trained athletes. LA size appears to increase with an increase in both the volume and intensity of endurance training. LA size correlates independently with the training age of endurance athletes. The athlete's characteristics that independently determine LA size include LBM, endurance training, and training age.