Abstract:
In a retrospective effort to study electrocardiographic changes indicative of exercise-induced left ventricular hypertrophy, eleven previously untrained men and women (mean age 39.9 years) participated in an approximate one year rigorous endurance type exercise program. Mean Frontal Plane QRS Axis and Total QRS Voltage methods of electrocardiographic assessment were utilized to detect left ventricular enlargement at different stages in the training program (initial, 3 month and one year). Changes in fitness associated with training were also measured by oxygen uptake analysis taken during graded exercise treadmill tests to exhaustion. Highly significant changes (p<0.001) in total QRS voltages, evidence of left ventricular hypertrophy (LVH), occurred over the one year training period. Significant changes were also found between the three month and nine month periods of the program. The mean frontal plane QRS axis method provided little corroborative evidence of LVH and in general was inconclusive. No significant relationship was demonstrated between total QRS voltage changes and changes in oxygenuptake (1 02/min) when a correlational analysis was performed. From this study it appears that small amounts of physiological left ventricular hypertrophy does result from a sustained rigorous type endurance exercise program.