Kazuo Asahina

Strenuous Exercise Electrocardiogram of Top Class Swimmers in Mexico City

The effect of strenuous exercise (60 knee bends in 1min.) on the electrocardiogram was studied in 8 top class swimmers in Mexico City (altitude 2, 240M.). The electrocardiographic changes during the 3 week Mexico training were compared with the responses in Tokyo.(1) Heart rate immediately after the exercise increased markedly on the second day in Mexico, and declined gradually. Heart rate before and immediately after the exercise remained at higher level during Mexico training than in Tokyo.(2) Average amplitudes of P waves before and after the exercise in lead II were taller during Mexico training than in control study in Tokyo, the most prominent P waves after the exercise being observed on the second day in Mexico. P pulmonale at rest was observed in 2 cases. Right axis deviation of P waves was observed in 3 cases. These changes in heart rate and P waves returned to the control value after coming back to Tokyo.(3) Amplitude of T waves in lead II decreased immediately after the exercise throughout the study. Decreased amplitude of T waves before and after the exercise was remarkable after 12 days of Mexico training.(4) The junctional depression of ST segment after the exercise was remarkable in the first week of Mexico training, and disappeared gradually in the following week.(5) Relative QT duration was increased 2 and 5min. after the exercise. Relative QT duration increased during the Mexico training both before and after the exercise.These electrocardiographic changes during Mexico training and anginal chest pain experienced during and after the race indicated the need for the careful health examination of the athletes.