Left ventricular size following endurance, sprint, and strength training.

Left ventricular size following endurance, sprint, and strength training. Med. Sci. Sports Exercise, Vol. 14, No. 5, pp. 344-347, 1982. Left ventricular dimensions in adolescent boys were determined before and after three types of training regimens: endurance (END), N = 8, means = 16.8 yr; sprint (SPR), N = 8, means = 16.3 yr; strength (STR), N = 12, means = 18.7 yr. With training the END group significantly increased VO2max in 1 X min-1 (3.71 +/- 0.27 to 4.16 +/- 0.57, P less than 0.05) and in ml X min-1 X kg-1 (58.4 +/- 5.6 to 64.2 +/- 5.5, P less than 0.05). The SPR group increased VO2max in 1 X min-1 (3.63 +/- 0.63 to 3.98 +/- 0.78, P less than 0.05) but not in ml X min-1 X kg-1 (59.5 +/- 4.1 to 63.2 +/- 5.4) because body weight increased from 61.2 +/- 10.5 to 63.1 +/- 10.7 kg (P less than 0.05) with no change in percent body fat. The STR training group significantly improved upper body strength. Despite these specific training adaptations no significant modifications were found for interventricular and left ventricular posterior wall thickness or for left ventricular internal diameter in either training group. However, calculated left ventricular mass was slightly but significantly higher by 10% and 4% in the END and STR training groups, respectively. These small increases in calculated left ventricular mass with short-term training are probably caused by small but insignificant increases in left ventricular internal diameter secondary to a training bradycardia (END group: 76 +/- 8 to 64 +/- 1 beats X min-1) and to increased diastolic filling time rather than to true cardiac hypertrophy. Significant increases in aerobic capacity and in strength can occur without modification of left ventricular dimensions.