EFFECTS OF CONTINUOUS PASSIVE EXERCISE AND CYCLE ERGOMETER TRAINING ON POSTMENOPAUSAL WOMEN

We examined the effects of endurance training on parameters of glucose flux during rest and exercise in postmenopausal women. Ten sedentary, but healthy women (55 ± 1 yr) completed 12 wk of endurance exercise training on a cycle ergometer [5 days/wk, 1 h/day, 65% peak oxygen consumption (V̇o2peak)]. Flux rates were determined by primed continuous infusion of [6,6-2H]glucose (D2-glucose) during 90 min of rest and 60 min of cycle ergometer exercise during one pretraining exercise trial [65% V̇o2peak (PRE)] and two posttraining exercise trials [the power output that elicited 65% pretraining V̇o2peak (ABT) and 65% posttraining V̇o2peak (RLT)]. Training increased V̇o2peak by 16.3 ± 3.9% ( P < 0.05). Epinephrine and glucagon were lower during ABT and lactate was lower during ABT and RLT ( P < 0.05), but the apparent insulin response was unchanged. Whole body glucose rate of appearance decreased posttraining during exercise at a given power output (4.58 ± 0.39 mg·kg−1·min−1 during ABT compared with 5.21 ± 0.48 mg·kg−1·min−1 PRE, P < 0.05), but not at the same relative workload (5.85 ± 0.36 mg·kg−1·min−1). Training resulted in a 35% increase in glucose MCR during exercise at the same relative intensity (7.16 ± 0.42 ml·kg−1·min−1 during RLT compared with 5.28 ± 0.42 ml·kg−1·min−1 PRE, P < 0.05). Changes in parameters of glucose kinetics during exercise were accomplished without changes in dietary composition, body weight, or body composition. We conclude that despite changes in the hormonal milieu that occur at menopause, endurance training results in a similar magnitude in training-induced alterations of glucose flux as seen previously in younger women.

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Hormone-replacement therapy use, but not race, impacts the resting and exercise-induced GH response in postmenopausal women

Acta Endocrinologica ◽

10.1530/eje.1.02006 ◽

2005 ◽

Vol 153 (4) ◽

pp. 527-533 ◽

Cited By ~ 4

Author(s):

J A Kanaley ◽

I Giannopoulou ◽

S Collier ◽

R Ploutz-Snyder ◽

R Carhart

Keyword(s):

Hormone Replacement Therapy ◽

Black Women ◽

Replacement Therapy ◽

Postmenopausal Women ◽

Racial Differences ◽

Hormone Replacement ◽

Cycle Ergometer ◽

Pulse Number ◽

The Mean ◽

Response To Exercise

Objective: This study examined the effect of hormone-replacement therapy (HRT) use on the incremental GH response to aerobic exercise in postmenopausal women and established whether racial differences in the GH response were seen at rest and in response to exercise. Methods: 13 white (n = 6, HRT; n = 7, no HRT) and seven black women (no HRT) were studied on two occasions, a control day and an exercise day (30 min at 70% VO2max on a cycle ergometer). Blood was sampled every 10 min for a 4-h period and analyzed for GH using an ultrasensitive chemiluminescent assay. Results: The mean 4-h GH concentration was higher on both study days in the HRT women than the non-HRT users. The integrated GH concentrations were greater in the HRT women both at rest and in response to exercise (rest, 352 ± 53 min μg l−1; exercise, 711 ± 57 min μg l−1; P < 0.01) than in the non-HRT women (rest, 157 ± 87 min μg l−1; exercise, 248 ± 94 min μg l−1). The incremental GH response was greater in the HRT users than in the non-HRT women (358 ± 130 versus 90.8 ± 94 min μg l−1, respectively; P < 0.05). GH-production rate during the 4-h period was greater in the HRT women than in the non-HRT women (P < 0.01), due to an increase in the GH mass secreted/pulse (P < 0.05), with no change in GH pulse number or GH half-life. No racial differences in the mean 4-h GH concentrations or integrated GH concentrations were found at rest or in response to exercise. Conclusion: HRT use resulted in a greater incremental exercise response compared with non-HRT users, due to changes in the secretory pulse characteristics in the HRT users. This study also demonstrated that no racial differences exist at rest and in response to exercise in the morning hours.

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Chronic hormone replacement therapy alters thermoregulatory and vasomotor function in postmenopausal women

Journal of Applied Physiology ◽

10.1152/jappl.1997.83.2.477 ◽

1997 ◽

Vol 83 (2) ◽

pp. 477-484 ◽

Cited By ~ 76

Author(s):

E. M. Brooks ◽

A. L. Morgan ◽

J. M. Pierzga ◽

S. L. Wladkowski ◽

J. T. O’Gorman ◽

...

Keyword(s):

Hormone Replacement Therapy ◽

Replacement Therapy ◽

Postmenopausal Women ◽

Hormone Replacement ◽

Venous Occlusion ◽

Cycle Ergometer ◽

Vascular Conductance ◽

Mean Body Temperature ◽

Doppler Flowmetry ◽

Vasomotor Function

Brooks, E. M., A. L. Morgan, J. M. Pierzga, S. L. Wladkowski, J. T. O’Gorman, J. A. Derr, and W. L. Kenney. Chronic hormone replacement therapy alters thermoregulatory and vasomotor function in postmenopausal women. J. Appl. Physiol. 83(2): 477–484, 1997.—This investigation examined effects of chronic (≥2 yr) hormone replacement therapy (HRT), both estrogen replacement therapy (ERT) and estrogen plus progesterone therapy (E+P), on core temperature and skin blood flow responses of postmenopausal women. Twenty-five postmenopausal women [9 not on HRT (NO), 8 on ERT, 8 on E+P] exercised on a cycle ergometer for 1 h at an ambient temperature of 36°C. Cutaneous vascular conductance (CVC) was monitored by laser-Doppler flowmetry, and forearm vascular conductance (FVC) was measured by using venous occlusion plethysmography. Iontophoresis of bretylium tosylate was performed before exercise to block local vasoconstrictor (VC) activity at one skin site on the forearm. Rectal temperature (Tre) was ∼0.5°C lower for the ERT group ( P < 0.01) compared with E+P and NO groups at rest and throughout exercise. FVC: mean body temperature (Tb) and CVC: Tb curves were shifted ∼0.5°C leftward for the ERT group ( P < 0.0001). Baseline CVC was significantly higher in the ERT group ( P < 0.05), but there was no interaction between bretylium treatment and groups once exercise was initiated. These results suggest that 1) chronic ERT likely acts centrally to decrease Tre, 2) ERT lowers the Tre at which heat-loss effector mechanisms are initiated, primarily by actions on active cutaneous vasodilation, and 3) addition of exogenous progestins in HRT effectively blocks these effects.

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Racial differences in the response of cardiorespiratory fitness to aerobic exercise training in Caucasian and African American postmenopausal women

Journal of Applied Physiology ◽

10.1152/japplphysiol.01077.2012 ◽

2013 ◽

Vol 114 (10) ◽

pp. 1375-1382 ◽

Cited By ~ 21

Author(s):

Damon L. Swift ◽

Neil M. Johannsen ◽

Carl J. Lavie ◽

Conrad P. Earnest ◽

William D. Johnson ◽

...

Keyword(s):

African American ◽

Exercise Training ◽

Aerobic Exercise ◽

Postmenopausal Women ◽

Racial Differences ◽

Cardiorespiratory Fitness ◽

Cycle Ergometer ◽

Aerobic Exercise Training ◽

Control Group ◽

Similar Response

African American (AA) women have an elevated risk of cardiovascular disease and have been reported to have lower cardiorespiratory fitness (CRF) compared with Caucasian American (CA) women. However, little data exist that evaluate racial differences in the change in CRF following aerobic exercise training. CA ( n = 264) and AA ( n = 122) postmenopausal women from the Dose-Response to Exercise in Women study were randomized to 4, 8, and 12 kcal·kg body wt−1·wk−13 (KKW) of aerobic training or the control group for 6 mo. CRF was evaluated using a cycle ergometer. A greater increase in relative CRF was observed in CA compared with AA women in the 4 (CA: 1.00 vs. AA: 0.35 ml O2·kg−1·min −1, P = 0.034), 8 (CA: 1.59 vs. AA: 0.82 ml O2·kg−1·min −1, P = 0.041), and 12 (CA: 1.98 vs. AA: 0.50 ml O2·kg−1·min −1, P = 0.001) KKW groups. Similar effects were found in absolute CRF, with the exception of the 4-KKW (CA: 0.04 vs. AA: 0.02 l O2/min, P = 0.147) group. However, in categorical analyses, the percentages of women who improved in both relative (>0 ml O2·kg−1·min −1) and absolute (>0 l O2/min) CRF were not significantly different for CA and AA women in all exercise groups (all P > 0.05). AA postmenopausal women, in general, had an attenuated increase in CRF (both relative and absolute) following exercise training, but had similar response rates compared with CA women. Future studies should investigate the physiologic mechanisms responsible for this attenuated response.

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