Journal
JOURNAL OF APPLIED PHYSIOLOGY
Volume 95, Issue 5, Pages 1963-1970Publisher
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/japplphysiol.00472.2003
Keywords
aging; sex; hyperemia; cardiac output; oxygen extraction
Categories
Funding
- NATIONAL CENTER FOR RESEARCH RESOURCES [M01RR010732] Funding Source: NIH RePORTER
- NATIONAL INSTITUTE OF GENERAL MEDICAL SCIENCES [T32GM008619] Funding Source: NIH RePORTER
- NATIONAL INSTITUTE ON AGING [T32AG000048, R01AG018246] Funding Source: NIH RePORTER
- NCRR NIH HHS [M01-RR-10732] Funding Source: Medline
- NIA NIH HHS [R01-AG-18246, T32 AG-00048] Funding Source: Medline
- NIGMS NIH HHS [T32 GM-08619] Funding Source: Medline
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The purpose of the present study was to test the hypothesis that leg blood flow responses during leg cycle ergometry are reduced with age in healthy non-estrogen-replaced women. Thirteen younger (20-27 yr) and thirteen older (61-71 yr) normotensive, non-endurance-trained women performed both graded and constant-load bouts of leg cycling at the same absolute exercise intensities. Leg blood flow ( femoral vein thermodilution), mean arterial pressure (MAP; radial artery), mean femoral venous pressure, cardiac output ( acetylene rebreathing), and blood O-2 contents were measured. Leg blood flow responses at light workloads (20-40W) were similar in younger and older women. However, at moderate workloads (50-60 W), leg blood flow responses were significantly attenuated in older women. MAP was 20-25 mmHg higher (P < 0.01) in the older women across all work intensities, and calculated leg vascular conductance (leg blood flow/estimated leg perfusion pressure) was lower (P < 0.05). Exercise-induced increases in leg arteriovenous O-2 difference and O-2 extraction were identical between groups (P > 0.6). Leg O-2 uptake was tightly correlated with leg blood flow across all workloads in both subject groups (r(2) = 0.80). These results suggest the ability of healthy older women to undergo limb vasodilation in response to submaximal exercise is impaired and that the legs are a potentially important contributor to the augmented systemic vascular resistance seen during dynamic exercise in older women.
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