Impaired leg vasodilation during dynamic exercise in healthy older women

1 Noll Physiological Research Center, 2 General Clinical Research Center, and 3 Department of Kinesiology, The Pennsylvania State University, University Park 16802-6900; and 4 Division of Cardiology, Department of Medicine, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033-0850 Submitted 6 May 2003 ; accepted in final form 17 July 2003 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 (20-40 W) 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. aging; sex; hyperemia; cardiac output; oxygen extraction Address for reprint requests and other correspondence: D. N. Proctor, Noll Physiological Research Center, The Pennsylvania State Univ., Univ. Park, PA 16802-6900 (E-mail: dnp3{at}psu.edu ).