This study addresses the contribution of connective tissue dysplasia (CTD) to the cardiac function in young athletes. Thirty-three cross-country skiers aged 15 underwent maximum stress-ECG and TTE before and immediately after stress-test. Global and regional function of LV was evaluated with the use of further image processing. We found that 87.9 % of athletes had phenotypic markers of CTD ranged from 12 to 26 score points. Parameters of LV global function at rest in all studied athletes corresponded to normal age-gender values but markers of regional function showed high degree of mechanical asynchrony that depended on extent of CTD. All athletes passed stress-test successfully and demonstrated a high level of exercise performance. Meanwhile, the variables of LV pump-function and mechanical asynchrony close correlated with CTD extent. Obtained results imply that the increase of CTD extent was accompanied by the decrease of scale of heart adaptation to physical loads.