Background Physiological cardiac adaptation in athletes is influenced by body surface area, gender, age, training intensity and sport type. This study assesses the influence of sport category and provides a physiological reference for sport category and gender.

Methods Three hundred and eighty-one subjects (mean age 25±5 years, range 18 to 39 years; 61% men) underwent cardiac MRI and ECG: 114 healthy non-athletes (≤3 training h/week) and 267 healthy elite athletes (mean 17±6.6 training h/week). Athletes performed low-dynamic high-static (LD-HS, n=42), high-dynamic low-static (HD-LS, n=144) or high-dynamic high-static sports (HD-HS, n=81).

Results Left ventricular (LV) end-diastolic volume (EDV) index (ml/m²) for non-athletes/LD-HS/HD-LS/HD-HS, respectively, was 101/107/122/129 in men and 90/103/106/111 in women. LV end-diastolic mass (EDM) index (g/m²) for non-athletes/LD-HS/HD-LS/HD-HS was, respectively, 47/49/57/69 for men and 34/38/42/51 for women. Left or right ventricular EDV ratios were alike in all groups. LV EDV/EDM ratios were similar in non-athletes/LD-HS/HD-LS athletes, and only lower in HD-HS athletes, disproving selective ventricular wall thickening in LD-HS athletes. Multivariate linear regression demonstrated HD-LS and HD-HS sport category coefficients (p<0.01) larger than those of training hours, gender and age (LV EDV/EDM coefficients for sport category LD-HS 6/0.75, HD-LS 16/7, HD-HS 21/17). ECG abnormalities were most frequent in HD-HS athletes and in male subjects.

Conclusions This study demonstrates a balanced cardiac adaptation with preserved ratios of LV/right ventricular volume (in all sport categories) and LV volume/wall mass (in LD-HS and HD-LS sports). Sport category has a strong impact on cardiac adaptation. HD-HS sports show the largest changes, whereas LD-HS sports show dimensions similar to non-athletes.