EFFECT OF PHYSICAL CONDITIONING ON CARDIOVASCULAR AGING CHANGES IN NORMAL MAN

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Because a major decline in physical conditioning status usually accompanies the aging process in industrialized societies, it is very difficult to separate the cardiovascular effects of aging per se from those of deconditioning. The following three studies seek to delineate the independent effect of these processes on left ventricular (LV) performance, at rest and during strenuous aerobic exercise. (A). To determine whether intensive physical conditioning can attenuate the well- known age-associated decline in early diastolic LV function, we performed resting Doppler echocardiography on 16 competitive male endurance athletes 52-76 years, 27 age-matched sedentary men and 17 sedentary men < 40 years old, all normal by history, physical exam and maximal treadmill ECG. Although VO(2max) in the older athletes exceeded that in both older and younger controls (47+/-6 vs 30+/-7 and 41+/-7 ml/kg/min, respectively), Doppler E velocity peak, E/A ratio and atrial filling fraction/AFF) resembled those of their age-peers and indicated significant impairment of early diastolic filling compared to young control subjects. These results indicate that even high levels of aerobic training and fitness do not generally offset the age-associated decline in resting early diastolic LV function. (B). To determine the effect of age and conditioning status on diastolic LV performance during intense aerobic exercise, we measured radionuclide ventriculographic peak filling rates at rest and throughout graded maximal upright cycle ergometry in 56 sedentary BLSA men and 12 highly trained old men. At rest, at 50% of maximum workload and at maximal effort, peak filling rates declined with age but were similar in older athletes and their sedentary age peers. Intravenous propranolol decreased filling rates in young (37+/-8 yr) but not in older (62q6 yr) sedentary subjects. These results sug-gest that the age-associated decline in early diastolic filling is over mediated by the deficit in beta-adrenergic responsiveness seen with aging. (C). To examine the cardiovascular effects of detraining in highly conditioned older men, we performed gated radionuclide ventriculography during maximal cycle ergometry in 6 senior athletes (aged 61+/-8 yr) before and after 12 weeks of deconditioning. Declines in VO(2max) (51+/-6 to 43+/-7 ml/kg/min), stroke-volume index (66+/-13 to 54+/-9 ml/m2) ejection fraction (87q5 to 80+/-4) and cardiac index (10.2+/-1.9 to 8.4+/-1.2 l/micro m) were noted after detraining. These results suggest that detraining reduces LV systolic performance during maximal aerobic exercise in highly conditioned older men.