An Italian and German research team carried out a meta-analysis on echocardiographic studies related to the left atrial enlargement in elite athletes.
Overall 2,425 top athletes and 720 active but not trained healthy controls were included in 16 studies. Average left atrium volume indexed to Body Surface Area was 37% higher in athletes as compared to non-athletic controls, the standard means difference being 1.12 ± 0.13. The standard means difference was higher in high-dynamic/high static trained athletes than in high-dynamic/low static trained athletes.
Scand J Med Sci Sports. 2019 Mar 13. doi: 10.1111/sms.13416.