New upper limit of physiologic cardiac hypertrophy in Japanese participants in the 100-km ultramarathon

Objectives The goal of our study was to define the structural characteristics of the heart in Japanese 100-km ultramarathon runners. Background During screening of participants in a 100-km ultramarathon, we found some participants who had larger cardiac chambers than had ever been previously reported. Methods A total of 291 male participants in a 100-km ultramarathon age from 20 to 73 years were examined using echocardiography. Results The mean heart rate (HR) was 50.6 ± 5.6 beats/min (38 to 79 beats/min), the systolic blood pressure (SBP) was 110.5 ± 5.6 mm Hg (94 to 138 mm Hg), the diastolic blood pressure (DBP) was 65.9 ± 6.6 mm Hg (58 to 90 mm Hg), the left ventricular end-diastolic diameter (Dd) was 61.8 ± 6.9 mm (42 to 75 mm), the left ventricular end-systolic diameter (Ds) was 39.6 ± 6.0 mm (23.0 to 55.0 mm), the interventricular septal thickness (IVS) was 10.2 ± 1.9 mm (5 to 19 mm), the posterior wall thickness (PW) was 10.0 ± 1.4 mm (5 to 15 mm), the aortic diameter (Ao) was 38.5 ± 4.0 mm (27 to 50 mm), the left atrial diameter (LA) was 40.2 ± 4.8 mm (26 to 49 mm), and the systolic wall stress (WS) was 221.5 ± 52.9 kdyne/cm2 (108.0 to 537.6 kdyne/cm2). Significant predictors of these parameters were the monthly running distance for HR, SBP, DBP, Dd, Ds, Ao, LA, and WS, as well as the age for IVS, PW, and Ao. Conclusions Thirty-three participants had a Dd larger than 70 mm. Moreover, some athletes had a larger aorta and left atrium than had ever been previously reported. The oldest runner was 73 years old.