Moderate and heavy oxygen uptake kinetics in postmenopausal women

The lack of estrogen in postmenopausal women not using hormone replacement therapy (HRT), compared with those using HRT, may reduce submaximal blood flow during exercise and result in an oxygen delivery limitation constraining oxygen uptake (VO(2) have been changed to V in the abstract, but will appear correctly in the body of the paper.) kinetics. The adaptation of pulmonary VO(2) (VO(2p)) during the transition to exercise in older women was examined in this study. Thirty-one healthy postmenopausal women (mean age, 61 +/- 6 years), 15 not using HRT and 16 using HRT, performed repeated exercise transitions (6 min) on a cycle, to work rates corresponding to 80% of estimated ventilatory threshold (moderate-intensity exercise) and to Delta50 (heavy-intensity exercise). There was no difference in moderate-intensity tauVO(2p) between non-HRT (40 +/- 9 s) and HRT (41 +/- 9 s) women. Similarly, there was no difference in heavy-intensity tauVO(2p) between non-HRT (44 +/- 8 s) and HRT (45 +/- 8 s) women. Thus, HRT did not affect the slowing of VO(2) kinetics of older women.