Left ventricular dimensions following training in young and middle-aged men

To document the effects of endurance training upon left ventricular dimensions, an echocardiographic examination was performed on 11 young (19 +/- 1 years) and 13 middle-aged (40 +/- 3 years) subjects before and after a 20-week endurance training program. The maximal working capacity was increased by 28% and 27% in young and in middle-aged subjects, respectively. Following training, the left ventricular posterior wall and septal thickness in diastole were unchanged both in young (10.1 +/- 0.2 mm and 9.0 +/- 0.2 mm, pre-; 10.1 +/- 0.2 mm and 9.3 +/- 0.3 mm, post-) and in middle-aged subjects (10.0 +/- 0.3 mm and 10.2 +/- 0.3 mm, pre-; 9.7 +/- 0.2 mm and 10.1 +/- 0.2 mm, post-); the left ventricular end-diastolic internal diameter was unchanged in middle-aged subjects (47.8 +/- 0.9 mm, pre-; 48.1 +/- 1.0 mm, post-) but was significantly increased in young subjects (47.8 +/- 1.0 mm, pre-; 49.9 +/- 1.0 mm, post-) (P less than 0.05). These data could suggest that the left ventricular adaptation to training decreases with age. However, the decrease in resting heart rate observed in young subjects (68 +/- 3 to 60 +/- 2 beats X min-1) (P less than 0.05) but not in middle-aged subjects (63 +/- 3 and 65 +/- 3 beats X min-1) could also increase diastolic filling time and explain the small left ventricular end-diastolic enlargement found in the young subjects.