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To examine the effects of age and chronic overload training on left ventricular systolic function during static exercise, Doppler echocardiography studies were performed in 14 young (28 ± 6 years) and 10 older (51 ± 3 years) weight lifters and also in 14 young (29 ± 6 years) and 10 older (52 ± 1.1 years) normal individuals during upright dead-lift isometric exercise, at 30% of maximal voluntary contraction for 3 min. At rest, older weight lifters demonstrated impaired left ventricular systolic function as compared with the other three groups. During exercise, peak and mean velocity values increased significantly (p < 0.05) from resting values in the young groups, but remained unchanged in the older groups. Flow period and acceleration and deceleration times were significantly (p < 0.05) lower in the younger subjects than those observed for the old ones, with the highest (p < 0.05) values obtained by the old weight lifters. This study suggests that the differences between the groups are related to differences in impedance and not to fundamental changes in the properties of the myocardium.

Hemodynamic and left ventricular systolic function were studied by Doppler echocardiography in 14 young and 15 older adult hypertensive patients and in 15 young and 12 older normotensive individuals. Measures were made at rest and during upright deadlift isometric exercise, at 30% of maximum voluntary contraction for 3 min. At rest, young and older hypertensive patients demonstrated impaired left ventricular systolic function compared to both old and young normotensive subjects. The impaired systolic function was associated with less augmentation in systolic indices during exercise compared with resting values in young and elderly hypertensive patients, and to a lesser degree in the normotensive elderly when compared with young normotensives. These data indicate that at rest, left ventricular systolic function may be compromised in hypertensive patients with left ventricular hypertrophy and, to a lesser extent, in the normotensive elderly. However, other factors in chronic hypertension may contribute to abnormal systolic function and override the effects of aging alone.

The exercise training workload for cardiac patients is determined from the peak heart rate achieved safely during a stress test. Circadian rhythms may play a key role in changing physiological responses to the stress test. Therefore, the purpose of this study was to evaluate the influence of the time of day on cardiopulmonary and metabolic responses in highly trained men with coronary artery disease. A group of 15 patients with coronary artery disease [53.5 (SD 6) years] performed two sessions of graded tests to exhaustion: one session was performed at 10 a.m. and the second at 5 p.m. in randomized order. Treadmill velocity was kept constant at a speed of 4.8 km h-1 starting with an elevation of 0% which was increased thereafter by 2.5% every 3 min. At rest the results revealed that only oxygen uptake was significantly lower (P < 0.05) in the morning compared to that observed in the evening [2.9 (SD 0.4) compared to 3.5 (SD 0.5) ml O2.kg-1.min-1, respectively]. During exercise, differences due to time of day were found in the variables of maximal oxygen uptake which were significantly higher (P < 0.05) in the evening than in the morning [34.2 (SD 2.6) and 40.8 (SD 2.5) ml O2.kg-1.min-1, respectively]. These data indicated that in these well-trained coronary artery disease patients there was a significant time of day effect associated with metabolic responses following stress-testing.

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