The physiological basis of training responses in women, and particularly older women, is not well understood. Short-term aerobic training (STAT) was used to probe the effects of age and hormone-replacement therapy (HRT) on women's ability to rapidly change peak uptake (VO2max), plasma volume and cardiac function. A total of 39 females participated in the STAT programme: 15 younger (Y; aged 19–29 years), 12 postmenopausal women undergoing HRT and 12 non-medicating postmenopausal (PM) women (aged 60–75 years). Training consisted of ten sessions of cycling over a 2-week period, which progressed in duration from 20 to 60min and in intensity from 60–75% of maximum heart rate. Plasma volume (PV; as determined by Evan's Blue dye dilution), VO2max (cycle ergometry) and cardiac function (radionuclide ventriculography) were analysed using analysis of covariance or repeated measures ANOVA. All groups demonstrated similar increase in VO2max (Y, 13%; PM, 17%; HRT, 13%), but without a significant change in left-ventricular ejection fraction and diastolic function or volumes during supine exercise. PV expansion was observed among the Y group (7%; P<0.05) but not the PM group (2%; P>0.05) or women undergoing HRT (1%; P>0.05). Age and hormone-replacement status did not affect the magnitude of VO2max change. This study suggests that STAT improves VO2max, independent of central adaptations.

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