Abstract. We studied a group of 18 top athletes (A) presenting the alteration of ventricular repolarization in right ventricular area ( mean age of 18 years + 5, mean stage in sport of 6 years + 3, 12 females and 6 males). They practiced long endurance exercise (14) or the resistance sports (4). We performed ECG at rest and during maximal exercise (exercise stress testing) by cycloergometer (2,5 – 3 watts / kg body weight), two-dimensional echocardiographic investigation at rest and immediately after exercise. We also studied a witness group of 15 top athletes (B). Group A presented some signs of R.V. dysfunction: the increased diastolic and systolic area (p<0,01) modified shape, the decreased RV descent (p<0,01). VO₂ max. was decreased . We found also an opposite effect of the maximal exercise on the right and the left ventricles: R.V. area increased while the left one decreased. This disproportionate effect was higher in long endurance athletes as compared with the resistance athletes. The explanation could be a disproportionate increase in R.V. afterload and an inadequate R.V. preload reserve caused by the decreased venous return. The changes of the R.V. shape and function during maximal endurance exercise seem to be a possible limiting factor of the effort capacity.

Key Words: Right Ventricle (R.V.), Left Ventricle (L.V.), Electrocardiogram (ECG) , Right Atrium (R.A.), Left Atrium (L.A.), Afterload, Preload, Ejection Fraction (E.F.).