ENDURANCE EXERCISE TRAINING AUGMENTS DIASTOLIC FILLING AT REST AND DURING EXERCISE IN HEALTHY-YOUNG AND OLDER MEN

Background. Diastolic filling at rest is altered markedly with advanci ng age. Whether exercise training can improve diastolic filling at res t or during exercise in either healthy older or healthy young men has not been determined. The purpose of this study was to determine if 6 m onths of aerobic exercise training improves diastolic filling. Methods and Results. Radionuclide diastolic filling parameters were measured at rest and during exercise in 14 older (age, 60 to 82 years) and 17 y oung (age, 24 to 32 years) rigorously screened healthy males before ex ercise training and in 13 older and 11 young men after 6 months of end urance exercise training. Diastolic filling rates were expressed in tw o ways, as absolute milliliters of blood (mL . s-1 . m-2) and normaliz ed to the end-diastolic volume. At baseline, the peak early filling ra tes were lower in the older group compared with the young group as exp ressed in absolute milliliters of blood (older, 85+/-7 mL . s-1 . m-2; young, 173+/-10 mL . s-1 . m-2; P less-than-or-equal-to .0001) and in end-diastolic volume per second (1.66+/-0.11 versus 2.55+/-0.08, P<.0 001), whereas the peak atrial filling rates were greater in absolute m illiliters of blood (85+/-5 versus 56+/-7 mL . s-1 . m-2, P=.003) and in end-diastolic volume per second (1.70+/-0.12 versus 0.80+/-0.06, P< .0001). During exercise, at any given heart rate, the older group had a lower peak filling rate than the young group. Also, at peak exercise , the single peak filling rate was decreased in the older group in mL . s-1 . m-2 (384+/-19 versus 565+/-36 mL . s-1 . m-2, P=.0002) and in end-diastolic volume per second (6.01+/-0.25 versus 7.91+/-0.28 end-di astolic volume per second, P<.0001). Six months of intensive aerobic e xercise training had similar effects in the old and young groups overa ll. Maximal oxygen consumption increased 19% (ANOVA training effect, P less-than-or-equal-to .0001) and echocardiographic left ventricular m ass increased 8% (ANOVA training effect, P=.002). Training increased t he resting peak early filling rate in absolute milliliters of blood by +14% (ANOVA training effect, P=.02). During exercise, the peak early or single peak filling rate at any given heart rate was increased. At peak exercise, the single peak filling, rate was increased by 14% in m L . s-1 . m-2 (ANOVA training effect, P=.0004). The only age-related d ifferential effect of training was on the peak atrial filling rate in end-diastolic volume per second, which decreased by 27% in the older g roup but was unchanged in the young (+5%) (ANOVA young versus older, P =.001). The independent predictors of a greater maximal oxygen consump tion by multivariate analysis were a higher peak exercise heart rate, a greater resting peak early filling rate, the exercise trained state, and a younger age. Conclusions. Healthy older men have reduced early diastolic filling at rest and during exercise compared with young men. Endurance exercise training enhances early diastolic filling at rest and during exercise in both the old and the young. Training reduces th e elevated resting atrial filling rate in the old, whereas the young w ere unchanged. The training-induced augmentation of early diastolic fi lling at rest and during exercise may be an important adaptation to al low an increase in stroke volume at rest and an increase in stroke vol ume, cardiac output, and maximal oxygen consumption during exercise.