Adaptations to short-term aerobic training in younger versus older women: Plasma volume and cardiac function

The purpose of this study is to elucidate responses to short term aerobic training (STAT) among women to determine: (1) hypervolemic and cardiac function responses and (2) the influence of hormone replacement therapy (HRT). A total of 39 females participated in the STAT program 15 younger (19--29), 12 postmenopausal women undergoing HRT, and 12 nonmedicating postmenopausal women (60--75 years). Cardiac function was assessed using exercise radionuclide ventriculography. Evans Blue dye dilution was used to determine plasma volume (PV). V&dotO2max was directly measured during cycle ergometry. Training consisted of ten sessions of cycling over two weeks at 65 to 75% of HRmax. PV and V&dotO2max measures were analyzed using an ANCOVA and measures of cardiovascular function were assessed using three way repeated ANOVA. All groups demonstrated similar magnitude of increase in V&dotO2max (13--17%) but without significant change in supine exercise radionuclide measures. PV expansion (7%) was observed among younger females (p < 0.05). HRT conferred no differing hypervolemic or cardiac responses. This study suggests adaptations following STAT among women do not result from central adaptations.