We attempted to study functional and structural changes in the hearts of volleyball players and cardiac effects of a short-term intensive training as disclosed by electrocardiograms(ECG's) and echocardiograms(UCG's).

In 12 volleyball players of a university team with the mean age and career of 19.9 and 9.2 years, respectively, comparisons of ECG's and UCG's M-mode & Doppler, were made before and after an intensive training of 8 weeks duration. The players have been trained 2-3 hours daily almost year around for many years, and the intensive and comprehensive training given for the current study was 3 hours daily, which included strenuous interval training of 20-30 minutes. The training was divided into two successive sessions. For the first session, the players ran 4km daily as a part of the training for 2 weeks. The second session included repetition of runnging at their maximal speed with short intermissions of stationary running for 6 weekes.

The major findings in ECG's were sinus bradycardia(25.0%) and high voltage(33.3%), and those in M-mode UCG's were left ventricular(LV) hypertrophy, LV dilatation or left atrial dilatation being seen in all cases, alone or in combinations. After the training however, there were no significant changes in the incidences of these abnormal findings in ECG's & UCG's, and also in the mean of various echocardiographic parameters reflecting cardiac functions. The E and A waves in Doppler UCG's also showed no changes. The slight but significant changes after the training were limited to the increases in the mean of the sum of S wave in V₁ & R wave in V₅, and left atrial dimensions.

In volleyball players who have been regularly trained for many years, the major findings in ECG's were sinus bradycardia and high voltage. Those in UCG's were LV hypertrophy. LV dilatation or left atrial dilation being seen in all cases, alone or in combinations. Nonetheless, after the intensive training of 8 weeks duration, the incidences of these abnormal findings in ECG's and UCG's remained essentially similar, and slight but significant changes were limited to the increases in the sum of S wave in V₁ & R wave in V₅, and left atrial internal dimensions. These facts suggest that in the regularly trained volleyball players, a short-term intensive training induces only limited cardiac changes as disclosed by ECG's and UCG's.