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IELLAMO, F., F. PIGOZZI, A. SPATARO, D. LUCINI, and M. PAGANI. T-Wave and Heart Rate Variability Changes to Assess Training in World-Class Athletes. Med. Sci. Sports Exerc., Vol. 36, No. 8, pp. 1342–1346, 2004.A decrease of electrocardiographic T-wave voltage with increasing training loads has been reported in elite endurance athletes and ascribed to training-related adaptation in sympathetic activity to the ventricles. A switch from vagal to sympathetic predominance in sino-atrial node regulation on going from low to peak training load has been reported in world-class rowers. In this study on world-class endurance athletes, we tested the hypothesis that training-induced variations in T-wave amplitude at higher training loads are paralleled by changes in HR spectral profile.We studied eight male rowers of the Italian national team in the season culminating with the Rowing World Championship. Athletes were evaluated at 50 and 100% of training load, ~20 d before the World Championship, and during the World Championship, when the intensity was markedly reduced. We assessed T-wave maximum amplitude in chest lead V6 and cardiac autonomic regulation by power spectral analysis of R-R interval variability.The increase in training load from 50 to 100% was accompanied by a significant decrease in high frequency and a significant increase in low-frequency R-R variability (in normalized units) with a concomitant significant decrease in T-wave amplitude (μV). Reduction in training load during the World Championship resulted in a return of spectral profile to the level observed at 50% training load and in a partial recovery of T-wave amplitude. HR did not change significantly.In high-performance world-class athletes, training load simultaneously affects both ventricular repolarization and HR variability patterns possibly through variations in cardiac sympathetic modulation to the ventricles and the sino-atrial node. Information on concomitant changes in ventricular repolarization and autonomic cardiac regulation might be employed to tailor training protocols of elite athletes.