INTRODUCTION: Interpreting repolarization changes in the electrocardiograms of athletes present a clinical challenge.

AIM: Assessment of cardiac repolarization by T-wave morphology using the Morphology Combination Score (MCS), and evaluate how this quantitative description of T-wave morphology was influenced by the sport performed.

MATERIALS AND METHODS: Digital electrocardiograms of 469 young elite athletes were analyzed for T-wave asymmetry, flatness and notching, and combined in the MCS. Athletes >22years were compared to a sex-and age matched control group from the general population (N=198).

RESULTS: MCS increased with increasing endurance component of the sport performed ranging from 0.79±0.15 (low) to 0.92±0.21 (high) (p<0.0001). All subcomponents of MCS were increased compared to controls. MCS was unrelated to age, sex and ECG findings of the athlete's heart.

CONCLUSION: This study suggests that sport induces repolarization changes detected by T-wave morphology, and a greater level of changes is seen in athletes from high endurance sports.